More from Vladimir Klepov as a Coder
Complaining about tech interviews is the favorite pastime of software engineers. We know they're broken, we've seen exactly how they're broken, but, despite a decade of collective hand-waving, we haven't fixed them. In fact, we haven't even understood why they're broken: "interviewers are stupid" is a tempting explanation, but most people I've worked with are quite smart, so it can't be the only reason. I stepped into hiring manager shoes as the job market was descending into AI panic. I've run over a hundred interviews, made a few dozen hires (with a few epic fails), and eventually led a redesign of our process for AI reality. After months of experiments and reflection, I think I see how this works. In this article, we'll trace how an industry full of smart, well-intended engineers created the lunacy of the modern tech interview. This story has it all: chance and fate, fear and bravery, good people crushed by the system that's set up to degrade. I might not have an easy fix, but at least we'll understand the mechanics of this death loop. Let's go! Hiring is not deterministic We engineers expect actions to have a predictable outcome. Assign a variable in code, beep bop, its memory register value changes. Cause and effect. Naturally, we want an algorithm for hiring that reliably separates good engineers from bad ones. Nice as it would be, this is not a realistic expectation. Imagine: I'm a good engineer, your interview process is great, you hire me. One month in, I decide that work is not really my thing, and I won't try that hard any more. The process was fine, but it failed to predict my performance, because the future is inherently uncertain. Hiring is, in essence, a binary classification problem: based on some observations, predict whether a candidate will perform well on our project. Apart from the good outcomes, we have two types of errors: False positive: we hire a candidate who turns out really bad at the actual job. False negative: we don't hire a candidate who would have been a great fit. With enough hires, we're statistically certain to make both types of errors. But their effects are drastically different. The error asymmetry A bad hire (false positive) is costly and visible. On top of the wasted hiring budget, a truly bad engineer creates security risks, damages architecture, and brings down production, all in a day's work. That's the kind of mistake that gets everyone's attention and causes unpleasant questions along the lines of "Vladimir what were you thinking hiring that guy"? Missed good hires (false negatives), on the other hand, are practically invisible. Usually, the rejected candidate just vanishes. In the rare case we accidentally learn they turned out to be a great success somewhere else, it's easy to shake it off — just because they're a great fit over there, doesn't mean they would've been any good over here. We might get some extra time-to-hire and interview load, but this is nothing compared to the costs of a bad hire, right? So, the conventional wisdom is "false positives, avoid at all costs; false negatives, fine". After a bad hire, we'd run a postmortem to understand what went wrong, and how to avoid all this trouble in the future. Focusing on false positives collapses the hiring problem into one dimension: if a low performer sneaked through, the bar was too low, and we must raise it by adding complexity. This makes tech interviews progressively harder. But is harder always better? The tale of two complexities Welcome to our software engineering interview. Here, a surprise awaits: to pass, you must win a game of chess against Grandmaster Anatoly Karpov, former Chess World Champion. This kind of interview will be very hard, but would it be good at selecting productive software engineers? Probably not, because chess is very loosely related to software engineering. While real-world interviews rarely involve chess (I wouldn't mind if they occasionally did), the core principle is clear. Interview complexity has two parts: Relevant complexity predicts the candidate's performance. Incidental complexity randomly eliminates candidates by unrelated criteria. Both kinds make the interview harder, but only the relevant produces useful signals. Incidental complexity produces random noise, and is essentially a time-consuming equivalent of making hiring decisions through dice rolls. "Got it, don't involve chess in the interview and I'll be fine" — I hear you say. But in practice, isolating relevant complexity can be tricky. Say, we're hiring for a realtime dashboard team, and we add a pretty relevant topic — WebSockets. Are we filtering on genuine experience, or on recent exposure to the technology? Does current WebSocket knowledge really predict the overall performance, say, 3 months in? Maybe we've done the right call, maybe we're playing chess — probably a bit of both. So, we're stuck piling up complexity based on our gut feeling. Every new topic inevitably adds some incidental complexity, causing more false negatives. This is bad enough for a single team, but once we zoom out to the organization level, things escalate. Scaling the noise All across the company, hiring managers are ramping up complexity. At some point, the inefficiency and inconsistency become obvious: some teams go so hard they spend all their bandwidth on endless interviews and rejections; others devolve into low-performer silos. In a noble attempt to balance the complexity, spread the load evenly, and cancel out individual biases, we introduce a shared interviewer pool composed of engineers from different teams. When done naively, this makes things worse. Say, a candidate writes all the code in a single huge function. Interviewer A thinks this rushed slop demonstrates a lack of decomposition skills. To interviewer B, this is pragmatic speed — the candidate prioritized delivering the product over architectural meandering. When hiring for their respective teams, both interviewers may be right. But now the context needed to ground this subjective decision is gone. If the interviewers swap candidates, we get two rejections. When both interview any candidate, at least one is likely to call a "no hire", because their preferences don't intersect. If the interviewers blindly act on each other's "green flag", they get inept candidates. Everybody loses. To counteract, we standardize the process through a shared problem pool and scoring rubrics. A perfect rubric is both relevant and objective, but this turns into an impossible balancing act. Leaning into alignment too hard dumbs down the interview with easily measurable questions like "can list the nine JavaScript data types". Any space for nuance and judgement is also space for subjectivity and misalignment: we're stuck arguing whether the single huge function is a valid balance of speed and maintainability. Balancing between dumbery and misalignment, we get a bit of both. The alienation Sadly, misalignment is children's games compared to the structural collapse that lies ahead. A hiring manager fully responsible for their hiring is not a perfect setup, but it gets one thing right: process and outcome are owned by the same actor. The labor of interviewing, the benefits of a good hire, and the pain of a bad one are all yours. A shared interviewer pool fractures this incentive structure. The individual interviewers get the accountability for a bad hire, but gain nothing from a good one. This leaves no incentive to make a more adventurous hire every now and then — when in doubt, just say "no". Group ownership of the hiring decision creates a perfect setup for bystander effect. Facing a barely-there candidate who narrowly misses all the red flags, an interviewer might think: if they're really bad, one of the other 5 interviewers will surely reject them. Once all the interviewers act on this logic, the barely competent hire happily progresses. The interplay between these effect results in a schizophrenic process that favors mediocrity. We reject "spiky" candidates who don't strictly fit our one-size-fits-all profile — say, a great systems engineer with subpar SQL. Meanwhile, borderline candidates get hired via bystander effect. Facing the full cost of running the interviews with a net-negative outcome, some interviewers grow disengaged. Our rubric, designed to help a motivated hiring manager stay objective, backfires. To a burnt-out cog in the hiring machine, it gives an easy way out: just mechanically check the boxes on our "green / red flag" list, and you'll be fine. Unknowingly, we've set things up for the final act. The snake bites its tail We've seen how the fear of bad hires makes interviews harder and more random, and ultimately cements them into a rigid process that's not owned by anyone in particular. But to close the feedback loop and see how this causes more bad hires, we must look at the other party — the candidates. Faced with brutal multi-stage hiring processes with lots of incidental complexity and a significant chance of random rejection, candidates adapt by overfitting to the incidental complexity of the interviews (aka interview prep). Instead of mastering what you do best, you grind leetcodes — or, even worse, practice cheating with AI. Instead of telling a messy war story, you polish a STAR advertisement with doctored success metrics. This is a classic example of Goodhart's law: when a measure becomes a target, it ceases to be a good measure. Before you know it, you're hiring great interview takers instead of great engineers. A strict rubric additionally sets things up for a nightmare scenario. For top companies, it's very easy to find not just generic interview prep, but a crowdsourced list of specific tasks used in the interviews. Once that happens, the process decays into who's done their homework. And behold, the snake has swallowed its tail: in an effort to avoid bad hires, we inadvertently set in motion the exact machinery that eventually made bad hires more likely. Time for some bar raising! Now that I've laid out all the pieces of the puzzle, I should propose the fix. Well, here you go. To make no hiring mistakes, don't hire. To avoid challenges of growth, don't grow. Once we break these rules, the snake starts eating its tail. We trade bad hires for random rejections. We trade nuance for alignment. We can make the snake eat slower, or pull out a few inches of the tail, but we can't save the snake, because it's driven by probability and the human mind. The best we can do is embrace the mess and keep at least some decency. Tomorrow, I'll log into zoom. I'll give the candidate the best problem we've got. I know it's not 100% relevant, but at least it's refreshing. The candidate won't cheat with AI because we explicitly allow and encourage AI-assisted solutions. If they hit any red flags on our rubric, I'll note this in my report. If they show exceptional promise in some unscored aspect, I'll note that too. At any rate, I'll be as friendly and engaged as I can, because even failing miserably at a random task doesn't mean you're a bad engineer. And even being a bad engineer doesn't mean you don't deserve respect.
My name is Vladimir, and I'm an engineering manager of a team building a banking app. Following the success of our core banking product, we've decided to expand to other financial services. In the last four months my team has grown 4x, going from a 4-person team to 4 teams totalling 15 people. It was, frankly, a shitshow, and now I see many things we could have done better. At first sight, increasing your team is a perfect way to speed up your product development. In practice, scaling is very challenging. Today, I'll share the pains of growth we've ran into: Disbalanced growth across functions. Teams becoming too large to manage. Processes breaking down. Mass onboarding challenges. Seniority skew. Now that it's all done, I can't say these problems were unexpected, or that our solutions have been incredibly inventive, but a first-hand account is worth writing down. Whether you're a leader expecting your team to scale, or just curious about the daily challenges of an engineering manager, hope you'll find something for yourself. Let's go! Scale evenly across functions You lead a 5-man engineering team. You'd like to build 2x the stuff you're building. The obvious solution is to hire 5 more engineers. Problem solved? Not so fast. Anything you build flows across several stages, each handled by a certain role, for example: product manager -> design -> engineering -> QA -> product analytics -> (back to) product manager. If you have a balanced flow with your current team, enlarging just the engineering will not make you more productive: Downstream functions (QA / analytics) can't keep up with the increased production — they must either put in overtime or downgrade quality standards. Upstream functions (product / design) can't fill the backlog fast enough, and the eng team has nothing to focus on, either slacking or refactoring the refactorings. With rapid growth, some temporary disbalances are unavoidable. It's fine to spend a few weeks or months in a disproportionate state, but overall aim for balanced scaling. Here are some tips to smooth the transition and even use the disbalance to your advantage: If you have any control over it, give product & design a hiring head-start. You can get their artifacts ready for development with a limited series of grooming meetings, and once the new engineers are on board, you'll have some great useful tasks to feed them. Catch up on your tech debt. Have too many engineers and not enough product tasks? Don't despair: use the time to clean up some old bugs, do the overdue refactorings, and prepare the codebase for the speed-up. Expand the area of responsibility. If you lack QA specialists, it might be time for the engineers to practice their testing skills. Oversized non-technical component (product / design) is more problematic, but you can give them some no-code tools to replace the eng team in some scenarios — e.g. build an admin UI where PM can edit the texts, create new banners, and so on, without involving your team. Update team structure Say you have a normal-sized team (4–7 engineers) with your average meeting structure (whole-team planning, grooming, and retro + weekly 1x1 with every team member). Making it a 15-person team won't work at all. An hour-long 4-person retro has 10 minutes of speaking time per member — enough to make a point. In a 15-person retro, it's 3 minutes — not practical. You either exclude some people, or extend the meetings — both poor options. It's harder to agree on any decision, because you now have 3x the possible objections. The 1x1s alone eat up 7 hours (almost a full day!) of your time a week. Managing communication of 15 people plus all the external stakeholders is time-consuming. The team must be split. What does it mean to be a separate team, anyways? Ever heard of "high cohesion and low coupling" principle in software architecture? I think this also applies to teams: Shared information space. Team members know what you're working on, where you're going, who your peers are, the system structure and so on. Own a well-defined part of the product and the codebase. A look at a random feature is enough to guess the responsible team. Control your processes — meeting structure, releases, etc. You can't be responsible for what you can't control. Have all the capabilities needed for your day-to-day work. Begging someone each time you need to deploy, change the API or add a banner is not very effective. It's best to split by product domain: customer acquisition team owns the landing page and signup, daily banking team owns the main app, and so on. You could split by layer (product + infra) or by function (backend + frontend + mobile) — I feel these compromise points 2 and 4, but let's not die on this hill today. At any rate, a team over 8–10 people must be split into sane-sized chunks to keep going. A note on grouping You can split a team by (A) building the new team out of newbies or (B) mixing newbies and oldies in each new part. Prefer mixing: it distributes the knowledge across the organization, and the social connections from the original team prevent siloing. You could argue that (A) keeps the original high-performing team intact, but it does so by slowing down the new team and undermining your long-term flexibility. Where to get new leaders? Splitting a team into 3 parts creates 2–4 leadership positions, depending on your place in the new structure. Ideally, you have senior members of the original team to lead the new teams, because it's a rare opportunity for career growth on a management track, and they can easily hire and onboard new members of their teams. If you don't have a suitable candidate (everyone is either very junior, or hates management), it's fine to hire externally — following a few hiccups, I recommend hiring people with prior leadership experience, because adjusting to a new product and a new role at once can be too much. Split iteratively You don't have to produce a fully separate team right away. As usual, move step by step — you get faster results, and can adapt to the issues that arise. Here's one possible sequence: Assemble a domain team, appoint one as the lead (you can call it trial-lead, to give them a chance to cop out). See how they like their new roles, and if the headcount needs tweaking. Run a retro for the new team to catch communication issues or cross-team dependencies early. Separate the domain backlog and kanban boards (or wherever you track the tasks). You'll need it for further process splitting, and to assess the team's load and velocity. Split planning and daily meetings, so that the teams don't waste each other's time on discussing irrelevant tasks. Gradually transfer the remaining processes (1x1s, onboarding, postmortems) to the new lead. Split the codebase, so that the new team can fully own its service. Update your processes Just like your single-team structure, the processes you have will likely fail for a larger team, especially if you have many newbies. Example: we had a liberal release process — if you want some feature in production, you deploy it. As the team grew, the release frequency dropped — the newbies were afraid to touch prod, the oldies were hoping one of the other 14 people would do it. Before I give you my solution to this puzzle, let's look at the general advice for process scaling. Localize processes to the new teams. Owning processes makes a team more effective. Retros, plannings, kickoffs, demos, daily stand-ups, releases, documenting, on-call duty, whatever you can split, do split. Yes, your overall team loses sight of the stuff going on across the system, causing duplication and poor decisions, but in return we can focus on a specific business area, and maximize productive time instead of drowning in discussions. If you need to offset the downsides, introduce a cross-team sync here and there (still working on this one). Let the new teams experiment with processes. What worked for your original team doesn't matter, that team is dead and gone. What works for one of your teams won't necessarily work for the other, because they work in different conditions. For example, our CA team has many time-bound tasks from marketing. The core banking team focuses on building quality software, and fixing the bugs as they arise. Very different teams. Start with a copy of your current processes (just to start somewhere!), and introduce team retros as early as possible to tweak the process as needed. Stricten the centralized processes. Back to our problem with deployment — we couldn't isolate the release process to sub-teams, because splitting a monolithic front-end into independently deployable parts is technically challenging. We introduced a more structured release process: The releases are automatically built and ready to deploy every morning. No more decisions to make. Daily rotation of release managers responsible for getting the release to production. With regular training, you get better at releasing. The release process is clearly documented. The newbies have a clear path to follow, making it less stressful. This works for other centralized processes — writing documentation, debugging with customer support, maintaining shared libs. Overall: hand over as much process as you can to the sub-teams, and introduce clear rules for the remaining centralized processes. The onboarding valley Surprisingly, fast hiring can reduce your team's productivity in the short term. The newbies are not yet up to speed, and the oldies now spend time explaining your codebase and reviewing code. This will fix itself over time, but here are a few strategies to get past the bump faster. Prefer slower growth. Adding one person every few weeks is much better than adding 6 people simultaneously, because: The "onboarding load" stretched over time occupies a smaller share of your team's resource. A few weeks in, new hires can already help onboard someone else. In some cases, they'll do a better job than any oldie, because their memories of one-off tasks like setting up the dev environment are fresh. Every onboarding exposes new roadblocks in your process, helping you smooth the next ones. On paper, batch onboarding might seem like a time-saver, as you can make a lecture explaining the basics to many people at once. In practice, unless your product is very small, or the tasks are very repetitive, every newbie faces very different challenges, drowning you with a wave of questions. Encourage peer-to-peer onboarding. As a leader, you might think onboarding is your personal responsibility. I call BS — peer-to-peer onboarding is clearly better: More "onboarding resource" leads to faster, better onboarding. The load on you, personally, decreases, freeing time to do other impactful things and, you know, live. Team members get a safe environment to practice their mentorship skills. People get to know each other, instead of only talking to you. ICs with recent hands-on experience do a better job at explaining the specifics than you. You can pair a formal "mentor" to every newbie, or direct questions to a team group chat. If you want to control the overall onboarding, at least route specific questions to team members experienced in that area instead of trying to come up with all the answers yourself. Write the docs. The best way to make onboardings cheaper is writing stuff down instead of explaining it over and over again, with your mouth. Some particular things to focus on: Onboarding checklist — the things every new team member must do: get a VPN certificate from the security dude, join this and that chat, clone a repo here and there, boom you're done. Only include essential steps — adding somewhat useful stuff obscures the actually important things. Document your existing business processes, system architecture, technical conventions, team and communication structure. It's better than explaining in real-time, because you get higher-quality charts, relevant links, and you can collaborate to put the knowledge of multiple team members in one place. Tooling and automation. The more automated a process or convention is, the less onboarding you need. Example: if you build your releases locally and upload somewhere via FTP using the keys you get from Piotr the devops, it's time to set up decent CD instead of documenting the current state of affairs. Pro tip: encourage newbies to improve and update the docs as they follow along — it's a great first contribution to your team! Senior vs junior hires It seems sensible to focus exclusively on senior hires. Experienced engineers get up to speed quicker, because they're already familiar with the basics, have a lower risk of making catastrophically poor decisions, and can bring good practices and ideas from across the industry to your team. Not so fast — here are some reasons to hire junior developers. With little exposure to the industry, they can easily adapt to whatever culture and processes you have. Anyone on your team can mentor a junior hire, while getting e.g. a junior engineer with decent knowledge of the product to mentor a newly hired senior engineer might be awkward, not very productive, or even taken as an insult. And of course, you can hire more junior engineers on the same budget. Overall, aim for a balanced team composition in the mid-term. You don't want your team to be a kindergarten, but a nursing home is no good either. Remember that people tend to gain experience, so the junior engineers you hire will become middle in no time. Today, we've discussed the challenges of rapid team growth — and ways to address them: Hiring more engineers won't speed you up unless product, design and QA grow to match. Start by growing product & design. If product lags behind, use the spare time to clean up the tech debt. Expand the area of responsibility of the oversized roles. Teams over 8–10 people are hard to manage. Split into chunks of 3–7 people, preferably by business domain. Mix old and new members in each team. Split step-by-step instead of going all in. The processes of your original team won't accommodate a larger team. Localize the processes to the sub-teams as much as possible. Let the teams tweak their processes to suit their needs. Stricten the remaining centralized processes. Onboarding is time-consuming, and can slow you down. Go slow: onboarding a person every week is easier than 6 people at once. Write the docs instead of explaining stuff over and over. Peer-to-peer knowledge transfer is better than onboarding everyone personally. Hiring only senior engineers is not a silver bullet. Aim for a healthy experience distribution in the mid-term. Hope these tips help you get past the scaling issues and up to speed in no time.
It's been almost 2 years since I moved to a team lead role, then to a full-time engineering management position after the expansion of our team. I've been a front-end developer for 7 years before that, and initially I took the "advanced individual contributor" career track before doing the management turnaround. How's it been? Bumpy, but fun. In this article, I'll share the things I love and hate about my current job. Love Let's start with the positive side of management positions. There's plenty to love, honestly. Impact First things first, I adore the power to improve the product we're building, and the overall team well-being that comes with a management position. As an engineer, you'll sometimes find yourself in a tough spot with little to no power to change things. Early morning standups are a chore? Code quality sucks? The new feature makes no sense? As a manager, the power to change is yours: you get both the formal and informal authority to change things for the better, and to make yourself and your team happier. Your words have weight. If you, an IC, say "guys, we really should write tests", everybody goes "oh, crazy old Vladimir, all grumpy again, haha, where do you see tests fit here?". If you, an EM, casually say "guys, we really should write tests", you might be surprised to find the tests unexpectedly growing in different places. Pleasant. Career opportunities Being an engineering manager is a more promising career opportunity than an engineering track. This might be controversial, but hear me out: The EM is normally higher-paid than the basic team-level engineering grades (junior / middle / senior). There are higher IC grades (staff, principal, president of code, whatever) in the EM+ salary bands. These staff+ IC jobs are concentrated in larger tech companies, because those have tougher technical challenges. Almost every software team in every company has a leadership position. The management career ladder is "taller" than that of ICs. Yes, the chances of becoming a CTO are slim, but it's an opportunity that's just not there for a pure IC with no management experience. All in all, I believe the demand for EMs to be steadier than for staff+ engineers, and this path gives you more opportunities at the later stages of your career. On a related note... Transferable skills Management skills are more widely useful than an IC engineering role. A decent front-end engineer with React experience won't have trouble moving to another front-end framework, and can probably transition to a back-end / mobile engineering role with -1 grade (a year handicap or so). That's not bad. What roles are available to someone with engineering management experience? First, you can easily take on a team with a wildly different focus — mobile developers, infrastructure, ML engineers. You'd need some time to get up to speed on the big-picture technical struggles of your new team, but most companies would take this shot. If you don't want to be an EM any more, you're well-positioned to move to a project or product management role. If the entire tech market falls into decline, many management skills would still work for other industries. While I don't see a big flow of tech managers moving into construction business (tech does pay well), there's one alternate path to consider — entrepreneurship. Involvement with people and business decisions makes for great training before starting your own business. So, being a manager gives you quite a bit of career flexibility, and makes you less vulnerable to future technological shifts. Less knowledge rot Suffering from front-end fatigue? Can't keep up with the newest shiniest frameworks and tools? Management's got you covered! The "hot new" agile / kanban / scrum methodologies are 20–30 years old. The basic meeting types (demos, dailies, 1-on-1s) have been developing for centuries. At the core, you have teamwork and human interactions, which haven't changed that much since the beginning of humanity. My grandfather was a big railroad boss in the 70s, and we can sensibly discuss some of my work challenges. "Oh, you have this talented slacker? Give him some big important task, let's see what he's worth." When it comes to computers, he's more like "I'd like a shovel big enough to throw all your silly gadgets into stratosphere." So, if you're tired of keeping up with the latest hot thing in tech, a management role can provide a well-deserved relief. Do keep an eye on what's happening on the tech side of things, but there's no urgency, and no need to get real deep. New challenges Frankly, after 4–5 years of working in a particular tech area, you can solve the vast majority of practical problems well enough. If you want some work challenge, you can: Slightly alter your stack — say, a new FE framework. But it's unlikely to keep you engaged very long. Make a broader career shift — e.g. frontend to backend. This would probably give you another couple years of fun, but such transitions are, in my experience, either random (e.g. your BE dev quits and someone has to fill the role), or hit your salary. Invent problems out of thin air — rewrite everything using a new library, or handle 9000 RPS "for the future". Fun, but most of the time it's more harm than good for your team and business. Of all the possible career moves a seasoned engineer can make, switching to management gives you the most new challenges (years worth of new stuff to learn) without hitting your salary. Hate As much as I like the challenges and impact of my new role, and the practical career benefits, I'll be the first one to admit it has downsides as well. Corporate BS As an engineer, I hated bloody corporate BS: individual performance reviews, useless deadlines, company-enforced restrictions on processes and tech stack. Well, congratulations, as a manager you are the sheriff of these practices, whether you believe in them or not. As a leader of a team in an org with performance calibrations, I must nominate 1 person who hasn't been working hard enough every 6 months. This human chess is soul-sucking, but I can't make it go away — if I don't offer a sacrificial teammate, someone will be picked randomly further down the process. Crazy shit. Sometimes you can negotiate a bit, or hack the process, e.g. assign "below-expected performance" on a round-robin basis, but to your team you'll sometimes be the corporate monster. Sigh. And I haven't even been through the real tough stuff like layoffs, closures and reorganizations. Awkward social situations I've made it to an engineering management position by being good at building stuff. I've been prepared to help with technical decisions, give career guidance, tune processes and set up automation as needed. In fact, a large portion of my job is debugging social tensions and psychological insecurities of people. Your junior engineer comments out a few tests to deploy a feature preview. The QA person sees this, and is very pissed because your whole team apparently does not respect the QA role and the value they provide. Restore trust. A project manager makes an unsuccessful joke that hurts your designer, who's now crying. Make the PM apologize. Am I a kindergarten teacher or something? Boy, I'm no psychologist, and I can't say I'm exceptionally good with people. This part of my job is quite hard, trying to fake it til I make it here. Office hours Life of an engineer is relatively relaxed. If you don't have anything urgent, you can go lay on the grass for half a day, thinking about the future of your project or something. You can miss a few meetings on short notice, no questions asked. Now, you're an EM. Try going and lying on the grass for a few hours. You come back to a messenger full of problems: your intern can't work because she forgot how to npm install; a senior manager wants to discuss some potential feature; release has derailed. Also, you can't really skip a meeting you're supposed to facilitate / organize without some up-front preparation. This might improve as your team matures and builds better processes, but in general you feel office hours much more as a manager, and your work-life balance directly depends on how good you are at your job. Long feedback loop The final thing I hate about management is the long feedback loop of your actions. Most engineering tasks show the result quite fast: new features take weeks to months, and if that's too long for you — fix a bug and see happy users the next day, or refactor some code and watch complexity decrease in a few hours. Amazing! You're a manager? Well, very few of your actions produce a visible result in under a month. Suppose your team has grown too large, and you want to split it up. You must pick a well-rounded set of engineers for the new team, talk to everybody involved to see how they feel about such a change, arrange new regular meetings, set up processes and communications, do some jira magic, maybe isolate the codebases of sub-products. If you think it can be done in a week, well, you're wrong. Then, even the right changes can make things get worse before they get better. Say you're understaffed, and you decide to hire. In the short term, you spend hours and hours interviewing, and a new team member won't get up to speed right away, sucking out precious time for onboarding. It's sometimes hard to see the long-term goal behind the short-term inconvenience. So, while engineering problem-solving is often fairly straightforward, management changes are more similar to large-scale refactorings. You won't see any quick improvements, which can be frustrating. To sum up, moving from an IC engineering role to a management position has been a rollercoaster ride for me, with both bright and bleak spots. Here's what I love: The wider impact on the product and team. Management is a great long-term career track: it gives you more job opportunities than a staff+ IC, the flexibility to move between different technical areas and roles, and skills that will be relevant across various industries for years to come. If you're bored with your field of tech expertise, moving to a management role is a great way to bring the challenge back into your job. And here's what I hate: Enforcing corporate decisions and policies can be soul-sucking. Dealing with social tensions and psychological insecurities of people isn't something I was ready for. It's hard to go offline even for a few hours without preparing in advance. Your actions have long and non-linear feedback loops with very delayed gratification. Now, is this career move the right one for you? If you enjoy challenge and responsibility, and you get an opportunity — I'd say go for it! Yes, management is not a fit for everybody (I'm not even sure it fits me TBH), but it's a great experience that would surely expand your skill set and make you see engineering work from a new angle. If you totally hate it, you have plenty of time to go back into coding =)
It's hard to believe, but, starting mid-october 2023 I conducted 60 technical interviews and hired 10 people into our team. It's been extremely tiring: around 80 hours of active interviewing, plus writing interview reports, plus screening CVs and take-home assignments, plus onboarding new members — all while doing my normal work stuff. Still, I feel like I learnt a lot in the process — things that would help me as a candidate in the future, and might help you land your next job. Note that I'm a fairly relaxed interviewer, and, as an internal startup of a large tech company, we generally have a more humane hiring process, so your mileage may vary. Still, I've done my best to pick the tips that I feel are universally applicable. Here are nine insights I took out of this experience, in no particular order: Be generous with your "expected income". Say you're a solid higher-middle engineer, and you ask for a senior salary. My thought process: OK buddy, it's a bit more than reasonable now, but I won't have to fight for your promotion 8–12 months from now when you get there, and I don't have to spend another 12 hours of my own time (and leave my team understaffed for another few weeks) looking for a real hardcore senior, so I'll let you have it. Now suppose you ask for a junior salary. It's suspicious — why is your bar so low? Is there someting about your work performance you're not telling us? So, do your research on reasonable salaries for your level of experience, and aim slightly above that. Ask the right questions. I always leave time for the candidate to ask me questions — obviously, this lets the candidate probe what it's like to work at our team, but it's also the best opportunity for me to learn what really matters to the candidate. I've never been much of an asker myself, but now I see that "Thanks, I have no questions" does not look good — if anything, it paints you as someone who doesn't care. Here's a short list of good questions: What does the daily work in this role look like? Harmless. What features are you building next? Caring about the overall product, nice. Sometimes the answer is "I can't disclose this secret", but not that often. Anyting about processes or team structure: how many people are on the team? How often do you release? What regular meetings do you have? Interested in organization, might want to be a team lead someday, great. Anything tech-related: which framework do you use? Why did you pick framework X? How do you test your app? Especially suitable for junior- to middle developers who are most involved in hands-on work. What kind of tasks do you see me doing? Again, just a good neutral question, because responsibilities for any role differ wildly between companies. What growth / promotion opportunities does this position have? Cool trick, flipping the feared "where do you see yourself in 5 years" question against the hiring manager. Here are a few questions that are not very good: Do you use jira and github? It's a minor detail, won't you be able to work with youtrack and gitlab? Do you sometimes work late? Only if something breaks, but overall this question makes you seem a bit lazy. People on poor teams that routinely overtime aren't likely to answer this question honestly, at any rate. Social skills matter. I understand that not everybody is super outgoing, but if we already feel awkward 1 hour into our acquaintance, why work together — to feel awkward for months to come? Just a few tips anyone can follow: Be energetic. You're tired, I'm tired, we're all tired of endless interviews. Are you just tired today, or generally always too tired to get anything done? I know it's easier said than done, but try and show me all the energy you have left. Show respect. People enjoy being respected. Very easy one: you have a great product. Sounds like you have a great engineering culture. This is one of the most interesting interviews I've ever seen. Like, I know you don't necessarily mean that, but subconsciously I'm very pleased: "oh yes, I'm very proud of my interview process, thanks for noticing" On a related note... Provide conversation opportunities. Q: Do you use TDD? Bad answer: "no". Good answer: "no, but I've heard of it. Interesting approach. Does your team use TDD?" Now you get to spend 5 minutes talking on your terms instead of being bombarded with random questions, and you come off as someone curious about stuff. On another related note... It's easy to hurt people. People normally ask you about stuff because they care about it. So, again, the interviewer askning "do you use TDD?", presumably, likes TDD and uses it. So, the worst answer: "no, TDD sucks, it's pure waste of time for idiots." A rare interviewer might appreciate you having a strong opinion on a topic, but to most this just paints you as a jerk, kinda like "Here's a photo of my children — "I hate children, and yours are especialy horrible". Not smart. Smart talk is not your friend. Saying stuff like "our front-end guild evaluated several cutting-edge approaches to testing universal applications" only makes you seem smart if you can elaborate on that topic: what these approaches were, the pros and cons you found, what tradeoffs you made for your final decision. If you can't answer a follow-up question beside "we settled on jest, not sure why", it was better to stay away from that topic altogether. Related: "in code reviews, I always consider the optimality of the algorithm selected" (proceeds to estimate the time complexity of comparison-based sorting as O(1). I never ask this unless the candidate boasts about her algo skillz). Admit your mistakes. Don't know an answer? Your code has a bug? It's always better to admit it and then try to come up with something at the spot than trying to talk your way out of it. Event loop? Sure thing, I'm an expert on loops. It's the way events are looped. Uses logarithmic weighing. Again, this makes you look like a candidate with big mouth and small hands. I have seen a couple of people who could talk their way out of any situation, but I honestly think with such skills you'd do better in a different line of work, like international relations, or selling financial services. Note that you really should give it your best shot — giving up at the first sign of trouble is not a good impression. If you genuinely have no idea — see conversation opportunity: "Event delegation? Tough luck, never heard of it. Would you tell me about it so that I learn something new today?" Make yourself memorable. It's hard to keep detailed profiles of 10 candidates in mind — after a good interview streak all I remember is the general impression (great / OK / horrible) and a few truly notable things. This guy worked for some crypto scam that went bust, that girl had a cute dog that was trying to eat the camera. The worst you can do is be a totally neutral candidate — we've had an interview, but I can't remember any details. So try and sneak some anecdote, or wear a silly scarf — something to remember. This point is especially important for intern / junior positions — online JS bootcamps do a good job of covering the basics, and it's really hard to differentiate these candidates. The memorable thing doesn't have to be professional, or even positive (even though it sure won't hurt) — your best bet would be some original personal project. Ask for feedback on the spot. Asking how you did at the end of the interview doesn't hurt. Yes, some interviewers will be hesitant to answer — at large companies, the feedback is normally sent through the recruiter, and you're never sure if sidestepping this process would get you into trouble. Besides, if the feedback is not complimentary, you're essentially asking for conflict at the spot, and people normally avoid conflict when possible. Still, it's a chance to adjust your expectations (if the interviewer says, looking you in the eyes, that you've done great, it's a good sign), and you might get actually useful tips that would probably get lost passing through the written report, and then through the non-technical recruiter.
I've been working with svelte exclusively for a year now, but I still manage to shoot myself in the foot every now and then when using reactive state. Some of the confusion is due to my prior experience with React, but some points are confusing on their own. Today, I dive into svelte internals to understand what's really going on. When you mutate svelte object state, do you really mutate the JS object? Why doesn't array.push trigger an update? How are $-dependencies determined? Does setting a variable to its current value trigger an update? Does a block using one object field, state.field, only run on changes to this field? Why do $-variables behave a bit weirdly under JS scoping rules? We won't talk about stores too much, we still have a lot to discuss before we get there. If you're in a hurry, here's a customary cheat-sheet: Let's go! Object state is mutable One thing that caught me off guard, coming from react, is that object state is mutable — the exact object defined as the initial value will stay there as long as you don't reassign the variable: // data is always the same object let data = { active: 0 }; const toggle = () => data.active = !data.active; <button on:click={toggle}> {data.active ? 'on' : 'off'} </button> See repl. By the way, this behavior also applies to stores. This is in contrast to react, where most optimizations rely on "purity" — a thing is only considered changed if its reference changes. So, svelte state is not an observable object built by JS means, but a regular JS variable with an update event bus attached separately. So far so good — the svelte way is close to how JS works. But what actually triggers the update event? Updates are triggered by assignment operator The big selling point of svelte is its concise syntax. As a showcase example, you often see what looks like simple JS, but changing the variable magically updates the component: let isOn = 0; <button on:click={() => isOn = !isOn}> {isOn ? 'on' : 'off'} </button> The magic disappears once you get to mutable objects — calling array.push() or any other mutating method does not trigger an update: let items = []; function addItem(text) { items.push(text); } {items.join(' ')} <button on:click={() => addItem('hehe')}> more! </button> This seems very familiar to react developers — of course, mutating the object does not change its reference, so further updates are skipped! To add to the confusion, react-style immutable update like items = [...items, text] fixes the problem. However, svelte state is mutable, and the real issue is the lack of an assignment operator which actually triggers the update, so the weird self-assignment pattern works just as well: let items = []; function addItem(text) { items.push(text); // #enable_magic items = items; } Any flavor of assignment operator (+=, ++, and so on) works, but it must be present for the update to happen. Another thing to note is that update logic is dynamic, not a strict "if callback X runs, fire listeners to variable Y" rule. The assignments are compiled to a call like $$invalidate(0, items), so conditional assignment only triggers updates if it's executed: // only triggers an update if text is truthy function addItem(text) { if (text) { items = [...items, text]; } } // always triggers an update function addItemAlways(text) { items = text ? [...items, text] : items; } Dependencies are determined statically Unlike invalidation, which happens dynamically at runtime, $-blocks dependencies are determined statically at compile-time. If you have some logic that only depends on text if isTracking is true... let isTracking = false; let text = ''; $: if (isTracking) { console.log(text); } ...the block runs on every text change regardless of isTracking value, because both referenced variables, text and isTracking, are recognized as the block dependencies. This is in contrast to runtime reactivity, as seen in MobX — there's no way to even see the dependency on text if the code accessing it does not run. One inconvenient side-effect of this dependency detection mechanism is the lack of visibility into implicit function dependencies. Say you have this code: let items = ['hello', '', 'friend']; const getNonempty = () => items.filter(x => !!x); $: nonempty = getNonempty(); Since the $-expression defining nonempty does not explicitly mention items, it will not run on items change. Fix: avoid functions in $-blocks, or make sure they're pure (only depend on their arguments), or (worst case) make the function itself derived: $: getNonempty = ... Primitive updates are pure Based on the points above, you'd assume that assigning to the variable always triggers an update, but that's not the case. When repeatedly setting a variable to true, only the first change results in an update: let isEnabled = false; // only run on the first click afterUpdate(() => console.log('updated')); $: console.log({ isEnabled }); <button on:click={() => isEnabled = true}> {isEnabled ? 'clicked' : 'click me'} </button> In general, setting a primitive variable to its current value does not trigger an update. Here's the svelte code that implements this optimization. Object updates are not pure But in that case, how on earth can this support object mutation and self-assignment that don't change the object reference? Well, the trick is simple — it doesn't. Wrapping isEnabled with an object removes the optimization, and now the update happens on every click: let state = { isEnabled: false }; // runs on every click afterUpdate(() => console.log('updated')); $: console.log(state.isEnabled) <button on:click={() => state.isEnabled = true}> {state.isEnabled ? 'clicked' : 'click me'} </button> The code implementing the comparison always says "it's changed" when it sees an object. Reactivity is variable-grained As we've just seen, object state is always treated as a whole — there is no field-level reactivity. If you have an $-block that only depends on a single field of the object, it will run on any change to the object: const fields = { clicks: 0, name: '' }; // runs on every "clicks" change $: console.log(fields.name); <button on:click={() => fields.clicks++}> clicks: {fields.clicks} </button> <input bind:value={fields.name} /> If we only want the $-block to run on actual name change, we can achieve that by extracting name to a separate reactive variable. This variable will have its own "change event", independent of other object fields. In our example it's better to just define the fields as separate variables from the start, but in general this can be done using a $-variable: const fields = { clicks: 0, name: '' }; // uses primitive comparison under the hood: $: name = fields.name // runs on "name" change only $: console.log(name); <button on:click={() => fields.clicks++}> clicks: {fields.clicks} </button> <input bind:value={fields.name} /> Note that object-to-object mapping does not optimize anything and just runs on every dependency change. This is because the "pure" optimization is only applied when all dependencies are primitive (computation is not triggered), or the output is primitive (further dependencies are not triggered). $-variables are an illusion If you've spent some time moving $-variables around, you know they behave weirdly from JS scoping perspective: You can reference the "scope" variables (declared with let / const) declared after the $-expression (in normal JS, this is TDZ) You can access $-variable anywhere in the script, but the value outside $-blocks is undefined Here's an example to illustrate this behavior: // you can reference variables before they're declared $: name = state.name; let state = { name: '' }; // logs "undefined" console.log(name); The trick is, again, simple — $-variables are just sugar over a simple let declaration and an $-block that assigns to the variable. The variable declaration is hoisted to the top (which is funny, because this perfectly emulates a var declaration), and $-blocks become callbacks defined after the synchronous initialization code. The un-sugared equivalent of the code above will be: // hoisted let declaration let name; // init block let state = { name: '' }; console.log(name); // $-blocks $: { name = state.name; } If you want to go one level down, the output in both cases is: let name; let state = { name: '' }; console.log(name); $$self.$$.update = () => { if ($$self.$$.dirty & /*state*/ 1) { // you can reference variables before they're declared $: name = state.name; } }; One funny side effect of this is that you can assign to the $-variable from e.g. another $-block, or a callback. The variable is not strongly bound to its definition, the last assignment wins. This would be quite confusing, though, and I recommend against such trickery. To summarize, here's the result of my research: Svelte object state is truly mutable. "Reactive variables" are just regular JS variables with change event bus attached as a sidecar. Updates are only triggered by assigning to reactive variables — assignment is compiled to $$invalidate(var_index, value) call. Reactive block dependencies are determined at compile-time based on variables used inside the block. "Pure" optimization only applies to primitive values. Variable is the smallest unit of reactivity — changing a single object field triggers all the blocks using this object. $-variables are compiled to a hoisted let declaration and a callback called after the setup code. Hope you've learnt something useful today — I sure have. Next time, we'll dissect svelte stores — follow me on twitter to stay updated!
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Download Now View on pouet.net Intro In the late 80s, I spent an embarrassing number of hours hunched over my ZX Spectrum, typing in Sinclair BASIC programs and rudimentary assembler routines copied from magazines, trying to re-create the Amiga crack intros I’d seen round at a friend’s house. Obviously, they never came even slightly close - but now, many decades later, I’ve finally managed it! I’m now the proud author of a hand-rolled retro demoscene intro that runs on a stock 128Kb Spectrum. It features all those late 80s tropes: A smooth scrolltext (with ‘leet custom fonts!), a three-channel AY soundtrack, bouncing VU meters and the essential parallax starfield. It’s currently 10287 bytes of code, or 19552 bytes as a complete tape image - which, given I’ve been working on this since December 13th last year, means my average rate of code-production is a paltry ~ 455 bytes per week! This blog post is a technical overview of how I got there, some cool tricks I picked up, and everything I had to learn (and re-learn) about the Speccy and Z80 assembly along the way. It simultaneously rates as one of my favourite side-projects ever, and also the one that most often nearly triggered a foot put through my monitor in frustration. I’ll reflect on all that at the end, but for now if you just want to see the finished product, the download button is at the top of the article and the included .tap cassette tape image should load into any emulator. There’s also a YouTube capture, links to the production on pouet.net, and you can run it from within a web browser by visiting my TNFS site portal - check option 4 for recent uploads. Be Kind, Rewind But let’s skip back briefly to the late 80s. Coming from the world of an 8-bit, cassette tape loading computer, seeing an Amiga for the first time was like encountering something from outer space. Like everyone who saw one back in the day, I was blown away by the amazing graphics and sound on display, not to mention the library of ground-breaking games. But I found myself even more captivated by the mysterious (and totally badass) “intros” displayed at the beginning of pirated games. Created by the software piracy groups that had cracked the copy protection and distributed the floppy-disk based games, they were mini works of art in their own right - music, graphics and usually some cool-looking effect to show off the group’s prowess. There’s a great collection of these intros (or “cracktros”) archived on YouTube. Watch a few of those videos and you’ll quickly notice the “design” tropes that almost every cracktro shares: a cool, edgy logo at the top of the screen (bonus points if it’s dripping blood or in any way “metal”), some boastful text displayed on top of an effect of some sort - usually a scrolling parallax starfield, or rotating 3d object - and a further scroll-text full of shout outs, greetings to fellow pseudonymous crackers and adverts for illegal BBS systems galore. Needless to say, to a kid in the 80s/early 90s this was possibly the coolest thing ever. I thought this one was the absolute bomb when I first saw it. Sine-scroller, pirate BBS adverts, cool logo with a sword - and of course, a starfield. There’s something for everyone here. The music from this is burned into my brain. I think pretty much everyone of my classmates knew this intro given the popularity of Lemmings in the early 90s. Skid Row as a group are still active to this day and this is probably the quintessential Amiga cracktro of the period. Endless Piracy. Edgy. Another cool logo, sine-wave scroller, starfield and boasting text. The classics never go out of style. Another great combination of all the essential ingredients. Cool logo, even cooler text font, scrolling starfield and a scroll-text running along the bottom. Vintage stuff. Logo. Text. Scroller. But no starfield - otherwise a solid effort from Anthrox here :) The demoscene grew out of these intros. The cracking eventually faded into the background, and coders, “graphicians” and musicians all contributed to feature-length productions that showcased their abilities, competed with other groups and pushed the machine to its limits. In amazing feats of ingenuity and pure “code as an art form”, the scene lives on today, with groups producing breathtaking productions like this and this - bear in mind, both of those are running on a 7Mhz home computer equipped with a floppy disk, 1Mb of memory and a sound chip from 1985. But much as I admire the sheer skill and dedication that takes, it’s the early “single screen” scrolly-text-and-starfield cracktros I’ve always found captivating. They took on a sort of mystical quality for me, hinting at a scene and a culture I could only ever experience from the outside - which is exactly why I spent all those hours in Sinclair BASIC, trying in vain to re-create them, and dreaming of the day I’d eventually have an Amiga of my own. The Jump Back I eventually did trade up to a range of Amiga systems, joined a few “scene” groups myself and threw myself into a variety of activities until exams and the end of my teenage years beckoned. I dabbled with Z80 code back then, and at one point knew enough 68k assembly to bluff my way through - partly from the Amiga’s heyday, partly from a few “embedded systems” modules at University where I had to program a set of traffic lights or lift-controllers. Given there’s not much call for that sort of thing at my $DAYJOB, though, it had all pretty much faded from my memory. I have kept working on a bunch of projects in my spare time, and one of my favourites is my TNFS site - sort of an old-school BBS system or interactive “website” for the Spectrum, which grew out of a fun experiment to see how far I could push Sinclair BASIC. It relies on a modern network card fitted to the Spectrum, which is how I came to be chatting to “Desertkun”, another TNFS-protocol enthusiast. He’s now producing a great new WiFi network card for the Speccy, and was kind enough to send me a few of the prototypes to test out for him. I was massively inspired by his hardware and low-level coding chops, and during one of our video calls where we’d been comparing our development setups, he asked why I didn’t write any Z80 assembly myself. A throw-away comment, but the challenge was set! Now, I couldn’t face re-writing the whole site in asm, but I figured I could produce a self-contained intro to promote it in the style of the early “BBStros”, and finally be one of the cool kids with a scene production of my own :) I mean, how hard could it be ? (ooooh - foreshadowing!) Dev Environment My development environment through this was pretty straightforward, and is the same stack I use for developing my TNFS site. I just used a Makefile-driven build system which ran my code through the Pasmo assembler, my fork of zmakebas to build BASIC files, and the FUSE emulator for testing. For final testing on the real hardware, I uploaded my .tap files to my local TNFS server where I could run them on my +3. A few additional tools I have to call out because they ended up making a big difference - one is the amazing web-based “asm-editor” I discovered while looking up Z80 instructions. Not only does this site have a great reference of all the Z80 instructions, but it also has an editor where you can run example code and see how the memory and/or various registers change state. Take for example, the djnz instruction - you can build it and step through the example loop construct one instruction at a time. Or try my example of an add instruction in the screenshot to see how the carry flag works when a bit gets shifted out of a register. Although it uses a slightly different syntax to Pasmo (so I couldn’t drop my code directly in it), it massively helped when manually stepping through things. And lastly, probably the most significant debugging tools I used on this project - a notepad and pen, and my two dogs (say “Hi!” to Biscuit & Pebble…) I’ll write some more about this in the wrap-up, but this really was a highly unusual project for me, coming from decades of much higher-level languages and constructs. Most of my z80 code I only ever really understood after drawing out the bytes and bitmasks, keeping a table of register flags and drawing chunks of screen memory out by hand. And I found my evening walks with the two dogs provided ideal rubber duck exercises, although I’m not sure what they both made of my protracted mutterings about the hl register pair. Either way, debugging-by-dog is highly recommended! The Starting Point So, let’s get started. I followed a great “Hello, world!” example from futurice.com to validate my build environment. Beyond that, the first thing I wanted to do was load in my logo and background image I’d use as a “stage” for the remainder of the planned intro. I wasn’t really sure what I was going to do at this point, just that I wanted my logo at the top, and a scrolltext along the bottom row of the screen. As my TNFS site header already looked kinda demoscene-y, I made a quick edit putting in place two blue guide-bars inside which I’d put further content. Memory map courtesy of breakintoprogram.co.uk A Spectrum SCREEN$ file (usually displayed as loading screens) is just a dump of screen memory, starting from byte 16384, and running for 6912 bytes. The weird layout of this is very relevant later, but in order to display it all you need to do is load your file into that memory location. After a few hour’s work of reviewing Speccy internals and following various guides, I had a very simple starting point for my demo that served as the basis for everything else that came after. org $8000 screen EQU $4000 ; address of the first byte of screen memory, 16384 in dec scrlen EQU 6912 ; total length of the screen memory inc. attributes ula EQU $FE ; I/O port for the ULA to control the border black EQU 0 ; Spectrum colour number, the exact same ones BASIC uses start: ld a,black ; Set the border colour to black using the ULA out (ula),a ; Copy my logo header picture to screen memory ld hl,header ; HL = location of my screen file in this code ld de,screen ; DE = start of screen memory ld bc,scrlen ; BC = 6912 bytes to copy ldir ; block copy, see https://jnz.dk/z80/ldir.html ; busy loop - rest of intro goes here :P hold: halt ; sleep until the next interrupt (1/50 second) jr hold ; then jump back and sleep again, for ever header: incbin "assets/header.scr" ; my logo header/background end start Not much to look at now, but this simple starting point introduced me to important concepts like interfacing with the Spectrum’s hardware (ULA chip to start with, and AY sound chip later) via the out instruction, how to pull in binary files using Pasmo’s INCBIN directive, using the Z80’s block copy ldir instruction, the use of register pairs for 16-bit addressing, and simple branching to labels. Hello World The next step was to print something on the screen and explore some of the Speccy’s built-in ROM routines, which are somewhat analagous to syscalls on modern operating systems. There are plenty of disassemblies and guides to the Spectrum ROM available on the internet, one of the best commented and linked one is at https://skoolkid.github.io/rom/. Using this as a reference alongside the various “Hello, world!” tutorials showed me how this sort of thing is built up: at EQU 22 ; "at" control character used to position the cursor row EQU 11 ; coordinates where to print the message col EQU 9 prstring EQU $203C ; where the pr_string routine lives in ROM ld de,msg ; DE = address of the first character ld bc,msglen ; BC = how many characters to print call prstring ; print the lot ; busy loop is the same... msg: db at,row,col ; equivalent of "PRINT AT 11,9" in BASIC db "Hello, world!" msglen EQU $-msg ; 16 bytes in all, pasmo shortcut, $=program counter I ended up mostly not using the ROM routines in my code as they dragged in all sorts of things I didn’t need, but it was massively useful to understand how they worked as they introduced me to yet more commonly-used constructs. For example, the PR_STRING routine defined here shows how you can build a loop over each character. If you’re just starting out, I highly recommend going over the 8 lines in that routine with a notepad and pen, working out the contents of the registers and following the loop constructs. I also made a version of it in asm-editor you can try. If you click that link, you’ll see a version of the code loaded into the web editor. Click “Build”, and then step through the code using the “Step” button - although no text will be actually displayed (I skipped over the call to the Spectrum ROM “restart” vector that does this), you’ll see the various states of the registers and for example the BC register counting down as each byte of the string is processed. Adding Some Style Problem is, the Speccy’s built-in font is not exactly dripping with demoscene credibility. I wanted to use some stylish fonts and this turned out to be super easy - a quick search turned up Jim Blimey’s awesome font collection, which included a ready-to-use set of assembler files and some instructions which soon led me to these additions in my code: ; CHARS is the address the ROM's printing routine reads to find the font. ; Picking our own font is simply a matter of over-writing this chars EQU $5C36 ; from Jim's docs - POKE 23607=5C36 in hex ld hl,myfont-256 ; HL = font address - 256 as per docs ld (chars),hl ; from now on the ROM draws with it! ; rest of code is the same myfont: include "textfont.asm" ; "Cartoon" font from jimblimey.com There we go! Now that’s looking a little more elite. Sorry, I mean 31337. Strap in folks, we’re leaving lamer city… So at this point, a month or so in to my dabblings and I’d started to get a reasonable understanding of common idioms and was starting to feel like this was a project that might actually go somewhere. The problem started when I moved on to trying to implement actual demo effects: It became very apparent, very quickly, just how much I didn’t know about how this all worked. Not to mention the fact that at this level, you’re really closely exposed to the physical hardware intricacies, including the design decisions and trade-offs that the hardware designers had to make when working with the extremely limited specs of the early 1980s. Cursed Screen Layout The first such problem - and the cause of probably 90% of my pain - is the Speccy’s extremely weird screen layout. Rather than standard bitmapped display you might expect on more modern hardware, it is instead split into 3 sections, each with a set of interleaved rows (so if you keep adding 1 to a screen address, eventually instead of reaching the next row, you’ll instead end up 8 rows down, and so on until you hit the bottom of the section and then loop back to the row underneath where you started!) followed by a block of “attribute” bytes which determine the colours of each 8x8 block. The attribute blocks are the reason why each 8x8 character cell can only have two colours (a PAPER and INK attribute) which led to the garish “colour-clash” of spectrum games and distinctive style where artists try to keep inside 8x8 blocks as much as possible. But it was the layout of the bitmap portion that is such a mind twister. Download the video You can see this illustrated whenever a game reads in a loading screen from tape. You can see each section built up with the interleaved rows one at a time, and then finally the colour and other attributes (like flashing ). There’s a lot of detail at the fantastic Break Into Program site. In the defense of the designers, they were working with extremely limited hardware and I don’t think the Speccy was ever imagined as a games machine. When you start shuffling bytes around, you realise that this approach is really optimised for displaying text which is neatly arranged into 8x8 character boundaries. For example, using this “scrambled” bit order, if you have a screen address in the hl register pair, you can quickly get to the next pixel line of a given address by simply incrementing the “high” byte. There’s a bunch of other “cheap moves” you can make by simply shifting bits around: Move Instruction Right 8 pixels inc l Left 8 pixels dec l Down 1 pixel line inc h Up 1 pixel line dec h Down 1 character row add 32 to l It was a reasonable choice for a machine that would probably spend a lot of it’s time displaying BASIC program listings - it’s only when you start trying to write demo or sprite routines that it starts to feel really weird. This also means you’ll pretty quickly need a routine to convert X,Y addresses to the relevant memory addresses. Again, L Break Into Program has a useful routine and if you disassemble more or less any spectrum game or demo, you’ll find a version of this procedure somewhere. And yes, this all became horribly relevant later on… The Scroller Download the video Admittedly, not the most interesting demonstration - but this was the first time I had made something move on the Spectrum’s screen with assembly! I watched this with pride more times than I care to admit :) I had a snazzy logo and “Hello World” text, but that doesn’t make for a very interesting intro! The first effect I wanted was the scrolltext - without that, it’s not really an intro. Now, the Amiga had all kinds of hardware sprites, blitter operations, custom chips but the Spectrum had none of that. I was going to have to work out how to do things the hard way - “banging on the metal”, literally by shifting bits around the screen memory by hand and having the CPU do all the work. This is where understanding the Speccy’s weird screen and character cell layout is so important. It turns out there’s a neat trick as long as I stay inside one character row - there’s a RL instruction, which takes a byte and “rotates” it left. It inserts whatever is in the carry flag into the rightmost bit, and whatever gets shifted out ends up in the carry bit again. That means if you string a bunch of them together, you can move a set of pixels across the screen - the moment they “fall off” one character cell, they end up in the carry flag and then the next rl instruction inserts them at the beginning of the next character cell to the left. Repeat 32 times, and you’ve just moved a pixel (or set of pixels) across a line of the screen: linestart EQU $4880 ; leftmost byte of the line 12 rows down lineend EQU linestart+31 ; rightmost byte column ($489F) linelen EQU 32 ; one whole line is 32 bytes (character cells) across dot EQU %00000001 ; the dot "shape", just one pixel lit at the far right end newdot: ld a,dot ; load the dot shape (only rightmost pixel lit) into a ld (lineend),a ; store it in the rightmost byte of the line, pixel is now lit frame: halt ; wait for the next frame, otherwise it whizzes across too fast to see ld hl,lineend ; hl = last (rightmost) byte of the line ld b,linelen ; loop counter, 32 bytes to work through or a ; trick to clear the carry flag, or against itself leaves a register ; unchanged but clears various bits including the carry flag ; see https://jnz.dk/z80/or_r.html shift: rl (hl) ; rotate this byte left (00000001 -> 00000010) dec hl ; point hl at the next byte to the left djnz shift ; loop construct: b=b-1 and then jump back to shift label until b=0 jr c,newdot ; now we've shifted the whole line, so if the carry flag is set now it means ; the dot has just left the screen, so we jump back to the start jr frame ; otherwise it is still somewhere on the screen, so keep shifting! Download the video Hell yeah. It’s almost a proper scrolltext now! Wrapping this in another loop that increments h each time (remember - that gets us moving down a scanline) gets us moving an entire character cell. Here you can see it moving an entire row of my “Hello world” message. There was however a lot more work needed to make a proper scrolltext, with each letter appearing smoothly. I started off by just printing an entire character at a time on the right-hand edge of the screen - it worked, but was pretty ugly as you saw each new character appear at once in the right-hand side of the screen, scrolling 8 pixels over and then the next character flashed up. Instead, I wanted to make each character appear pixel by pixel and that required a bit more bit juggling. The routine I ended up with effectively streams each character in, line by line, pixel by pixel using the font data directly instead of calling the ROM print character routine. It does this by looking up the ASCII code for a character, and then fetching the corresponding font representation into a 8-byte buffer, one byte for each line of data. The font data starts with the space character (character code 32), so a lookup is simply font code base address + (ascii code - 32) * 8 to get to the bits for that letter. Arranged into an 8x8 grid, the bits for the letter H in the font data look like this. For each row of bits, I shift the line left using a neat trick. The byte is loaded into the a register, and then by adding itself to itself - add a,a we shift the value left (in binary, multiplying by 2 moves everything over one bit) so that the pixel I want to draw ends up dropping into the carry flag. This is an idiomatic way of doing it in Z80 code as it’s faster and smaller than the sla instruction. And every cycle quickly adds up when you’re re-drawing 256 bytes every frame! The character buffer then looks like this, with the top line shifted. Now, with the hl register pair pointing at the correct location on the screen, I can then use the rl trick discussed above. This shifts a scanline from the bottom character row of the screen left by one pixel and draws my pixel in the rightmost position by moving it in from the carry flag. Looping 32 times over this moves the entire row by 1 pixel with my new pixel inserted at the right. I then repeat this step again using inc h to move down one scan line until the entire character column has been drawn. At this point, the character buffer looks like this, and all 8 lines of the bottom screen row have all been shifted left by one bit by looping over all 32 character columns. The whole thing then repeats another 7 times until the entire character has been smoothly scrolled onto the screen. So just to re-state this because I think it’s worth the emphasis - just to scroll a message across the bottom of the screen, we’re having to loop over and re-draw 256 pixels every frame! It shows how much faster assembly is than the BASIC interpreter built into the spectrum’s ROM. I found it amazing to see my code finally working and imagining all the bits flying around and registers flapping away. It really makes me appreciate just how much effort went into creating the games I played back then. Music The original Amiga module I converted. A proper 1980s ear-worm! Of course, any good intro needs some music. On the Amiga, the standard was the “tracker” module format, which has a long and involved history of different forks, versions and tweaks. A song is built up from a series of patterns, each made up of rows of instructions. Each instruction usually includes note or pitch information, which sample to play and various parameters such as volume, effects - or in the case of some instructions, which position in the song to jump to. In many ways, it’s almost like a programming language for music. Using ProTracker as an example, a typical note cell is 4 bytes, shown on-screen as something like C-2 01 C20. That breaks down into three fields: the note and octave (C-2), the sample number (01), and the effect and its parameter (C20 - in this case, “set the volume to $20”, which is half of the maximum $40). A close-up of Protracker playing a tune. Note the VUmeters - another classic demo effect I would pinch later on! For an impressive demonstration of what’s possible with a tracker and to see what the note data looks like on-screen, check out the work of h0ffman, and in particular his winning “Professional Tracker” entry from the Revision 2014 competition. He’s an undisputed master of the science (or art!) of tracking, and his “Secrets of Protracker” talk gives a great overview of what’s possible. The Amiga’s sound hardware far eclipsed anything else on the market at the time, and the ZX Spectrum is paltry by comparison. The original 48K models only offered a rudimentary “beeper”, but the later 128K models included a 3-channel AY-3-8912 sound chip. This was very popular in 8-bit micros of the time, and a more-or-less identical variant was also used in the Atari ST. While it only offers basic waveforms and sound processing, it does enable multi-channel “chip music”, and so it became the mainstay of the ZX Spectrum demoscene. It also spawned a variety of SoundTracker clones on the Spectrum itself, although most musicians these days prefer to work in modern tools like Vortex Tracker II, which runs natively under Windows. The Conversion Pex looking back on his demos - this starts at the point where he features my letter and plays a bit of my cover version! For my intro, I wanted to port an Amiga module - and I had the perfect one in mind. One of my favourite Amiga music disks was “Sounds Of Gnome”, released in 1989 by the Swedish duo “Mahoney & Kaktus”. Mahoney also wrote NoiseTracker, one of the first really widely used trackers on the Amiga, and the program that served as my teenage introduction to making computer music of my own. Back in 2018 I made a rock cover of one of the other tunes on that disk, and wrote to Mahoney (real name “Pex”) about it. He ended up showing my “music video” at a demo conference, which I am eternally grateful for! So it seemed only fitting that I mangle another song from that collection with a Spectrum conversion… Sorry, guys! I picked the track “Milkman” which was written by “Glue Master”, an associate of Mahoney’s who had a few of his tracks featured on the compilation. It’s an ideal track for converting: It’s short (only 7 patterns in total), most of those patterns share the same chord sequence, and it looked fairly easy to squeeze the original 4 channels down into the Spectrum’s 3. Plus, it’s an incredibly catchy tune and I knew it well - I’ve been listening to it for 35+ years and often jam along to it on guitar or bass. The conversion started off pretty easily: all I really had to do was copy the patterns note-for-note from the Amiga mod, which I had open in OpenMPT as my Windows tracker. Below is a session with both trackers open on the same pattern - the original Amiga mod on the left, and my 3-channel Spectrum conversion on the right. Note the 11.7 in the 3rd channel of the Spectrum version. This is a “pitch slide down” effect in Vortex Tracker syntax, which drops the pitch by about a quarter-tone. It’s repeated on the next line, so the overall effect is a slide down from the A# that leads in to the next bass note. The original Amiga mod does the same thing using its own syntax - those are the 202s you can see on the same notes, at the bottom of the 4th track. Using just a single “beep” sound for everything was enough to check everything was working, and after a few weeks of hacking on it and re-arranging things in the evenings, I had a basic version which sounded surprisingly good for a first draft: Download the MP3 instead. I have to give a special mention to this forum post which was a massive help getting me started. It’s probably the best introduction to Vortex Tracker I’ve found - many, many thanks to the original author for taking the time to write it all up! The real challenge was making it sound as close to the original as possible. That meant building up a library of better-sounding samples for the different parts, and making extensive use of Vortex Tracker’s “ornaments”. Vortex Tracker comes with a great selection of sounds, and fortunately I’m also a weirdo who likes to listen to chiptunes in the background while I work! So whenever I found something particularly enticing, I filed it away for later pilfering inspiration. A Vortex Tracker sample isn’t really a “sample” in the Amiga sense of a recorded sound - it’s a definition of how a note sounds, one line per frame. Each line can mix in a tone or the white noise generator (useful for snare effects and suchlike), along with various other parameters. Ornaments, on the other hand, give you extra control over what pitch a note plays - and this enables really useful tricks like “arpeggio chords”. For example, an ornament of 0,4 makes the channel switch rapidly (25 times a second) between the note being played and the one 4 semitones above it. It happens so quickly that it sounds much like two notes played at the same time, which means you can build up full-sounding triad chords using only two channels. Take the opening chord in my fully converted version, Cm: It plays C in the first channel and the minor 3rd (D#) in the second, then I apply an ornament to the second channel to bring it up 4 semitones to the 5th (G). That gives all three notes of the chord, while keeping the 3rd channel free for other parts. As well as making much more efficient use of the limited 3 channels, this also gives Spectrum music that characteristic “warbling” sound, which I find really appealing in a retro kind of way! Between tricks like this and samples that mix tones with white noise (to make a combined “bass-snare” sound, for example), I managed to condense the full track down to 3 channels. Many months later, I have to say I’m really pleased with the final result. Playback The original site that was home to Vortex Tracker, documentation and other resources appears to be offline at the moment. I managed to grab a copy of everything I needed from archive.org - you’ll want the PTxTools.7z file for the playback routines discussed here. The playback was simple in theory: As this overview notes, you basically just pull in the player routine, include your module file and call the playback routine once per frame in your main loop. The catch is, none of the source code versions supplied in the archive worked with my Pasmo assembler. Fortunately, there is a pre-compiled binary object shipped alongside the source (VTII10bG in the PTxTools/PT3Play directory). This just has to be loaded in at address $C000 - this cannot be changed, as it has lots of absolute addresses baked in. My code to handle module playback now looks something like this, with the binary module loaded in place: ; Define the start address of the player routine and functions we need player EQU $C000 ; hard-coded org address of binary player plinit EQU player+3 ; init function in docs, module address in hl plplay EQU player+5 ; play and move on one frame ; from the docs - this "analyzes PT3 module header and prepares ; corresponding note and volume tables" ld hl,moduleimg call plinit ; main loop hold: halt call plplay call scroll ; other effects / routines go here... jr hold moduleimg: incbin "assets/music.pt3" Starfield Download the video Well, that didn’t work as hoped. TNFStro - tortoise edition. This brings me to the main event. No self-respecting cracktro is complete without a starfield! My first, naive approach to the classic starfield effect was to scatter random stars across the screen, then move down each scan-line applying the same rl trick I’d used for the scroll-text. I figured I could get parallax by shifting each row a different amount: One pixel for the first row, two for the second, three for the third, then back to one again, all the way down the screen to give the impression of several “fields” of stars moving at different speeds. It turned out there were two major problems with that approach. Firstly, shifting an entire row smeared whatever else was on it along with the stars - which I’d expected, and had filed away as a problem for future me. The bigger issue was speed: by the time I’d finished the first three rows I’d already performed hundreds of shift operations, and it was nowhere near fast enough to fit inside a single frame. Everything crawled across the screen, and the music playback slowed down so much that you could actually hear the arpeggio ornaments warbling away as separate notes. Clearly I was going to have to keep track of the individual stars instead. I found this routine, which was more-or-less what I had in mind and started me off with the idea of a structure to hold the state of each star. It also uses a screen address lookup much like the one from “Break Into Program”. Download the video Dammit. Back with another funeral dirge rendition :( That got things moving, but the co-ordinate lookup and tracking proved expensive to do (it has to run for every star, every frame as well as keep track of the old position for erasing) and I’d been ignoring the bigger question how to display stuff on top of the starfield. My original idea was simply to draw the stars and then paint text over them each frame, which blew the frame budget just as comprehensively as my first attempt. If I wanted something more interesting than an empty starfield, I’d have to keep track of which cells were occupied by text and avoid drawing stars in them in the first place, rather than over-painting them every time. After lots of scribbling in my notepad and visualising rows of bits, I eventually solved both challenges by “cheating” fairly liberally. So now, I don’t generate a random starfield at all. Instead, I built a table of pre-calculated Y and X position pairs: stdata: defb 109, 25, 88,182, 42, 96, 155,226 defb 59,254, 137,169, 160, 84, 125,193 ; ... and so on, for 32 stars ... This saves faffing about with an RNG, and once I have a layout that looks good I know it’ll always look good. I can also “fudge” things and ensure no two stars share the same y co-ordinate which sidesteps a whole class of problems like stars sharing a scanline, and having to deal with them overtaking each other. The “random” layout is generated by a simple Ruby script: #!/usr/bin/env ruby PAIRS = 32 PER_LINE = 4 # pairs per line Y_RANGE = 40..175 # exclude rows taken up by my logo & bars X_RANGE = 0..255 raise "y range too small" if Y_RANGE.size < PAIRS # no duplicate y values ys = Y_RANGE.to_a.sample(PAIRS) pairs = ys.map { |y| [y, rand(X_RANGE)] } pairs.each_slice(PER_LINE) do |row| body = row.map { |y, x| format('%3d,%3d,', y, x) }.join(' ') puts "defb #{body.chomp(',')}" end When the routine initialises, I convert those co-ordinate pairs into a table that tracks the state of each star. So rather than storing a position and translating it to a screen address every frame, each of my star records now looks like this (offsets from the base address): STSCR EQU 0 ; screen address of the byte the star is in, e.g. $4123 STOCC EQU 2 ; a pointer to the "occupancy check" table cell STMASK EQU 4 ; the star's bit pattern, e.g. %00010000 STSTEP EQU 5 ; "speed" - num. of pixels this star travels per frame The key thing is that there are no X/Y co-ordinates at all. For each star I store the screen byte it sits in and the bit mask within that byte, so it’s already in the form the screen writes need. That means no address conversion per frame, just simple bit shifting and rotation. Moving a star is then dead simple. I rotate its mask left with rlca, and when the bit rotates out of bit 7, it lands back in bit 0 with the carry flag set. That’s the signal I need to move the star one character cell to the left, which is one of the “cheap moves” from earlier. Because I’m tracking which cell each star is in, the collision check comes almost for free. That’s what the second pointer is for: STOCC (Star Occupancy) moves in step with STSCR through a table holding one byte per character cell. The “typewriter” routine sets a byte to 1 for every cell containing a text character or the cursor, so checking whether a star is hidden behind text is a single or instruction. If the cell is occupied, I skip drawing the star but carry on rotating and stepping it along until it reaches a cell where it can be displayed: ld l,(ix+STOCC) ld h,(ix+STOCC+1) ld a,(hl) ; A = the occupancy check for this cell or a ; test A against zero jr nz,stmove ; it's occupied, so leave the screen alone Parallax is still handled by moving each star a different number of pixels per frame, but the cost is a lot lower this time as I’m only touching the cells the stars actually occupy, rather than every byte of every row. Download the video That’s looking more like it! The typewriter routine is a simple copy of the font data from memory, and is very cheap as we can use the “cheap moves” to quickly fetch the 8x8 block. I also skip drawing any space character so it leaves the “occupancy cell” unmarked. This means the stars keep drifting through the gaps in the text - you can see here the odd star passing in between the words. I switched to ALL CAPS writing for the final version which helps the effect even more as the font is quite blocky, so you don’t really notice stars skipping the spaces inside a glyph at all. Misc Notes A few odds and ends that didn’t warrant a section of their own… VU Meters Some sort of graphic display bouncing along with the audio playback was another common early demo trope. I did originally consider a real-time graphic equaliser, but that would have been far too complex, probably in terms of spare cycles per frame, and definitely in terms of my limited mental capacity at this point! So I settled for a simple set of bouncing meter bars instead. It’s worth a mention mostly because it gives me an excuse to link to the awesome chibiakumas website! I just love the late 90s web design on display - one can argue that readability and accessibility take a hit, but it’s just so much fun to encounter a site that still looks like this. It’s a clear labour of love and there’s a wealth of content there as well, if your eyeballs are up to it. Their guide on Making Sound with the AY-3-8910 was what showed me how to get the data I needed to draw the meter bars. The examples write a register number to $FFFD to select a register, and I realised that once a register is selected, I could use the in instruction to read its value back out instead of writing a new one. As the page says, R8, R9 and R10 hold the channel amplitudes, so they feed nicely into the height parameter for drawing a bar. Getting the amplitude for channel A is then as simple as: ld a,8 ; Channel A register call ayread ; ... rest of code here ... ayread: ld bc,$FFFD ; Register select port out (c),a in a,(c) ret Twinkle, Twinkle, Little Star This is a simple effect that makes the header logo a little more interesting. I’m not sure where I originally got the idea - I’ve definitely seen something like it on a few late 80s/early 90s demos, though. All I wanted was to pick random star dots in the logo background and animate them. Here’s the header image loaded in ZXPaintbrush with the character cell grid showing. By happy chance, there are four stars which each sit neatly inside a single character cell with enough surrounding space, so they can be used to give an animated “twinkle” effect by drawing a cross out from the centre point and back in again. These dots map to the following co-ordinates, which target the top scanline of each fully-grown star (two pixels up from the centre): twkdata: defb 1,5 ; char row 0, col 5, centre y=3 ink 5 defb 1,20 ; char row 0, col 20, centre y=3 ink 1 bright defb 26,7 ; char row 3, col 7, centre y=4 ink 4 defb 25,22 ; char row 3, col 22, centre y=3 ink 6 bright The “twinkle” routine itself is simple enough: it adds a pixel on either axis to grow the star, waits a few frames, then shrinks it back down again. The interesting bit was how I made the twinkle order pseudo-random. Remember that my starfield was entirely pre-calculated from a data table generated by a Ruby script, which meant I’d never actually needed a random number generator in assembly. From Jonathan Cauldwell’s “How To Write Spectrum Games” e-book, I found another great “hack” which simply walks through the start of the Spectrum’s ROM, picking out random-looking bytes as it goes. As he says, he uses it in most of his games, and it does the job in a really simple way - as long as you stay below the block of structured, repeating data that sits 8Kb into the ROM. twkrand: push hl ld hl,(twkseed) ld a,h and 31 ; keep it within the first 8k of ROM ld h,a ld a,(hl) ; the "random" byte inc hl ld (twkseed),hl pop hl ret Out Of Space About halfway through writing the intro, I hit a fairly predictable problem: I had run out of memory. In an attempt to keep everything self-contained in one block of code, I was pulling all of the assets (the screen background, the player binary, the music file etc.) into the program itself, and then using the ldir block copy instruction to move each one into its correct location. Since that meant effectively storing every block twice, and the player routine had a hard-coded start address of $C000, I quickly ran out of room and my code started crashing into the playback routine. The simplest option was to split things out into separate code blocks, load each one directly to the address it needed to live at, and wrap the lot in a multi-stage BASIC tape loader: 10 CLEAR 32767 20 BORDER 0: PAPER 0: INK 0: CLS 30 LOAD "" CODE 40 LOAD "" CODE 50 LOAD "" CODE 60 RANDOMIZE USR 32768 This loads the main program, then the player routine directly into $C000, and finally the background screen straight into screen memory. It does mean the background starts appearing before the demo has fully loaded, but as I imagine most people will be seeing this running in an emulator or on my TNFS site, it doesn’t really matter. Plus, at this point I was in danger of disappearing down yet more rabbit holes (I still really want to work out how to do multi-colour border effects!) and I’d never have got this thing released. The Zen Of Z80 This whole project is a really weird one to look back at. On the one hand, I’ve fulfilled a childhood ambition and have something I’m very proud of. It’s also pretty unusual these days to end up with a binary where you can say pretty much what every single byte is doing and the story of how it got there. But on the other hand - I now have an answer for why I don’t code in assembly: It’s because I value (what’s left) of my sanity! The thing is, in order to write code like this you have to start thinking like the machine itself. You have to visualise the registers and the status flags flapping away, graphics as lines of bits slotted into strange orders, loops and conditionals as binary logic and so on. Getting this close to the hardware definitely brought about a greater sense of attachment to the hardware of my childhood, and it’s easy to see why assembly coders and sceners get so passionate about it. That said, I’m in no hurry to start re-writing my body of work in assembly! The projects I really enjoy are those that give me an excuse to learn something for the sheer hell of it, and to slow down a little from the ever-increasing velocity and demands of the modern work world. Going back to Z80 code is probably about the furthest I could have taken this, short of going into hardware hacking. I found it at times an intriguing puzzle, often a frustrating exercise that nearly had me throwing in the towel at several stages. This project has certainly taken the longest to go from the “idea” stage of any given feature to any kind of meaningful output. True, I didn’t spend every day of the last year working on it - my actual coding time was probably only a few hours over a couple of evenings a week. But I’ve certainly been thinking about it and pondering it most days (as my dogs will attest). The biggest breakthroughs and “aha!” moments usually didn’t come from behind the keyboard; they came from scribbles in my notebook and thinking about processor states while doing something unrelated. It has however given me massive appreciation and respect for the coders who pull this stuff off and make it look easy. And that goes double for those kids and bedroom coding superstars who managed all of this back in the 80s, and had to work it all out by experiment themselves. I only managed to get this far because of numerous books, online tutorials, GitHub repositories with sample code, YouTube videos… I can’t imagine how much longer this would have all taken me if the only resources I had were my Spectrum, a cassette tape recorder and a notepad. So, as I draw a line under this project - for now! - I raise a glass, and in the words of h0ffman: “Shout out to the hackers, graphicians and protrackers.”
A decade ago, a little bit of history was made. I didn't realize it, but a colleague made a great point, one of those real mind-changing points that seem too obvious to admit same-day. But, the next day, calver.org was born. At the time my team maintained the Python infrastructure for eBay and PayPal, and we were stuck deciding whether we were really ready for a "major" 1.0 release. Semantic Versioning was the only game in town and "major" means "big", right?! Thankfully, a wiser colleague mentioned: Ubuntu and Twisted don't struggle with version number debates. They slap a date on it and keep shipping. In fact, their date-based versions were even better because you always knew where it stood, in terms of updatedness and support. The only problem is that no one really knew about it. Somehow, this problem solving versioning alternative, arguably as old as history itself, had gone nameless for millenia, conspiring to make me feel foolish in an office meeting. Never again! Ten years of adoption Fast forward 10 years, we've seen CalVer adopted by Apple, Nvidia, JetBrains, and countless others. (We have a timeline!) The site may have more inbound links than any other project of mine. Apple made the biggest jump, at WWDC 2025: iOS went from 18 to 26 macOS from 15 to 26 watchOS from 11 to 26 and visionOS from 2 to 26 All landing on one, consistent number like a car's model year. I still remember the texts from the Venn diagram fanbase of my friends who love Apple and reasonable versioning. No such texts from when NVIDIA announced calendar versions across the GPU Operator, RAPIDS, and its monthly NGC containers, but still very cool. Open source, too: Home Assistant, pip, CockroachDB, and yt-dlp all ship on dates, with plenty more on the users page. The conversation even reached the language core; PEP 2026 proposed versioning CPython as 3.YY, and it almost happened, too. And it's never too late, time marches on! Fixing the notation But I don't think I got every detail right from day 1. That's the main motivator for CalVer 26. It's high time to start righting a couple idiosyncratic token design choices, starting with some additions: Meaning Before 26.0 26.0 Full year YYYY YYYY Short year (6, 16) YY YY Zero-padded year (06, 16) 0Y 0Y Short month (1 ... 12) MM M Zero-padded month (01 ... 12) 0M 0M Short week (1 ... 52) WW W Zero-padded week (01 ... 52) 0W 0W Short day (1 ... 31) DD D Zero-padded day (01 ... 31) 0D 0D Seeing double First, the doubled letters. From the first version (16.6), MM and DD meant the unpadded month and day, which reads backwards to anyone who knows date formats (ISO 8601's YYYY-MM-DD, Java, moment.js, day.js), as some community members correctly pointed out. I was ready to flip them, until I checked what people actually use: most projects with a YY.MM.MICRO badge (conda, Twisted, Ansible's tooling) don't pad, and more than a dozen other version management tools (like bumpver and bump-my-version) implement the old meaning. So, it's too late to flip MM's meaning. Instead, 26.0 deprecates it and offers a more explicit and hopefully clearer option: M is the short month, 0M the padded one, and MM is a technically-retired synonym for M. In case you're wondering, the explicit 0M was me being overinspired by Ubuntu's approach, perhaps: 6.06 pads its month but not its year, and YY.0M says exactly that. To pad or not to pad I think it's worth a detour into why padding is even a thing anyways. It's become important now that new ecosystems have emerged that enforced SemVer formatting semantics, and I wanted clear guidance about on the spec site. SemVer forbids leading zeros outright, so Cargo rejects 26.04.0 and Go modules reject v26.04.0. Even Python's packaging spec normalizes leading zeros away, so you can tag 2026.08.19 if you want, but PyPI will still show 2026.8.19. NVIDIA's GPU Operator docs put it this way: "Zero padding is omitted for month to be still compatible with semantic versioning." CalVer was always intended to drop in where SemVer was used. So 26.0 recommends unpadded (YYYY.M.D) as a sane "pure" default for software libraries. But libraries are not the only objects of versioning schemes. The exception is a version that becomes a filename, an image tag, or an object-store key that gets listed lexically. There, padding keeps 26.10 sorted after 26.09, which is why Ubuntu, NixOS, and NVIDIA's own NGC containers pad. More evidence of teams designing their versions. We love to see it. Our FAQ has a longer discussion of the padding issue, as well. Optional segments There was never any rule against them, but 26.0 makes optional trailing segments more explicit with square brackets. Now, yt-dlp's scheme can finally be written down: YYYY.0M.0D[.MICRO]. For the CalVer badges I could find on GitHub, they all stay valid for now. I've got a note on the deprecated spellings and a new copy-paste badge section for new ones. What else is new? It's always a great time to add more citations to the site. A spec changelog; the spec now versions itself: 16.6, 19.7, 26.0. A FAQ: breaking changes, same-day releases, and padding. The users page, rebuilt by category, with past users of note (schemes change; that's fine) and tooling. Case studies: Apple and NVIDIA in, yt-dlp replacing youtube-dl. Much of the thinking behind these changes happened in the GitHub issue tracker over the years, and 19 or so issues close with this release. That's where ideas for CalVer should go, so by all means, open an issue, and we'll get it sorted! In due time, of course. In closing, I can't believe I still love belaboring these numbers so much. Thanks to all (but especially Mark, Glyph, Hugo, issue reporters, translators, and maintainers) for the discussion, and ultimately making the most timely versioning system a timeless classic. See also 2016 announcement Designing a version My Yap on Why CalVer beats Semver
Four sincere attempts at OKRs, four failures, and every time: "you didn't do it right." Maybe the framework doesn't fit you -- so how do you find one that does?
Multiple concurrent writers. Multiple processes. Same SQLite. No modifications.
Brilliant jerks, ZIRP-era managers, and how psychological safety lost the plot. Part 3 of my conversation with Dr. Cat Hicks.