More from Willem L. Middelkoop
This weekend I ran the marathon of The Hague. I gave everything, and the result was 3 hours and 40 minutes. I am satisfied, because I know there was really nothing more in it. Tired legs, maximum heart rate, and still no collapse. It is beautiful that you can look for the limit like that. But the most important part of this marathon did not happen on the road. It happened in the weeks before, at home, looking out of the window. Two marathons in four weeks Four weeks earlier I ran Köln. Two days before the start my body was fighting a virus. I slept extra, stopped working and switched the computers off. The next afternoon I wrote: "the body is winning, energy is flowing through the veins again". Köln became 3:48:27. The Hague went better in every way. The extra experience made it possible to operate longer at the maximum: eating, drinking and the mental side were better than ever. I understand very well now what makes the performance. And it is not only the training. The Hague, 1 November 2026, just before the start Work as a long run At the end of October I wrote something less cheerful in my notes. Not only sport, but work too had taken on the character of a long run. Steady, long, without an end in sight. More than ever before, the balance tipped to the negative: no sparkling fun, warmth or pleasure. "It really is a marathon. I am physically, and mentally, ready for rest." That is the trap of a pace you can hold: you can hold it so long that you forget you are running. The answer was not to stop. It was to stay pragmatic, limit the loss of energy, and focus on the things we want to influence. And nothing more. Room to breathe On 15 October I did something different. The phone on "do not disturb" and out of reach. Questions about the jam supply and the invoices came in, all very important, for later. Reachable for emergencies, but there was no emergency. I wrote: "The best in me comes up when there is room. This is not running away or hiding. It is a necessary pause to breathe." Three days later, on a Sunday, I tried a whole day with zero screen time. A small experiment to feel where we still depend on it. Physical things stood out more: clutter, dust. Conversations with the children were easier, because I had so much more bandwidth to ask good questions. And I simply looked out of the window. I thought about my body, about the fast food of the day before, and about how little I really need. A green, orange or red light would be enough. The Sunday without screen time: wood, a plant by the window, daylight on the table That light exists now. The home screen of Contact, the software I work with every day, is one dot. Green means: all is well, nothing is waiting for me. It took a Sunday without screens to see that one dot was enough. The home screen of Contact: one green dot, nothing is waiting Why a window works Looking out of the window is not doing nothing. In 1984 Roger Ulrich published a small study in Science. Patients recovering from the same operation, in the same hospital, were given a room with a view of trees or a view of a brick wall. The ones looking at trees went home sooner, 7.96 days against 8.70, and needed fewer strong painkillers. A view, nothing more. There is a name for designing with that in mind: biophilic design. Daylight, plants, wood, a view and a place to retreat to. I only learned the word properly this autumn, while building levendkantoor.nl for Martin Cuypers, a client in Venray, not far from home. Their page on what biophilic design is puts it in three layers: nature in the space, nature as a reference, nature as an experience. Reading it, I recognised my own Sunday. Wood under my hands, a plant by the window, daylight on the table. Nothing to buy. Just noticing. As is, not add-on The morning after The Hague I wrote down the conclusion. The gym is no longer "nice to have". We are making it an integral part again, on days that keep the impact on working hours small. The goal: a strong physical base, not as an add-on, but as is. Next year I want to break 3:30, and that can only happen if we make everything stronger, in all dimensions: strength training, sprints, and longer runs at low intensity, around 130 beats per minute. An hour on the treadmill, then a round on the machines Last week I ran an hour on a treadmill, followed by a round on the machines. I loved it. An hour on such a thing asks for a different mindset, and that is exactly the point. Like the window and the green dot, it is not something extra on top of the work. It is what my work stands on, the foundation for thinking. I wrote about running before, in Marathon and in Run Nicely. This time the lesson is not in the legs. Conclusion Two marathons in four weeks taught me more about work than about running. The pace you can hold is not enough. You also need room: a morning without a phone, a Sunday without screens, a view of something alive. The best in me comes up when there is room, and that room is not a reward for after the finish. It is part of the training. There is one more race on the calendar this year, purely to finish, at a slower and conscious pace. First recover. And look out of the window a bit more, ha! The best part of a finish: celebrating with friends!
My mail, WhatsApp and Signal now live in one app I built myself. I called it Contact. It is not a chat app and not an AI app, it sits somewhere in between. When I tried to draw what it is in my notebook, a factory came out. This post explains that drawing, starting with a puzzle. A puzzle for the class At Jurre's school the day starts with a "binnenkomer", a small opening activity, and every child takes a turn. The message that it was his turn next came in through the WhatsApp group of his class. So one evening Jurre sat down and made his own: nine dots, and a rule. "Je moet elk stipje in een eigen vakje hebben, maar je mag maar twee vierkanten tekenen." Every dot in its own box, but you may only draw two squares. Jurre's puzzle: the rule on top, nine dots, and one of the solutions He wanted copies, a clean one for everybody. I took a photo, which lands in my own photo library at home within seconds. In Contact I opened a session and typed what I wanted: take the latest photo, make a printable page with the text and the empty puzzle, without the solution, and print it. One page first. The agent did not know where the printer was. It scanned the network, found a Canon that was asleep, told me so, and waited until I switched it on. Along the way it found the original message from the class group in Contact's own WhatsApp archive, so it knew what the page was for. The session in Contact: the agent looks for the printer, I tell it what to make Printing, on a printer that nobody had set up for this The first page came out faded, one cartridge was nearly empty. The agent found a print mode that still gave deep black, and then the copies came out. Within the hour there was a stack on the table: the empty square, the nine dots, the rule in a proper font. The next morning Jurre took them to his class. The result: the puzzle without the solution, ready to hand out in class That small evening has everything in it. Someone has an idea. It comes in, somebody decides it matters, a machine with enough context and energy turns it into a thing, and the thing goes back to the people. That is the factory. The drawing The drawing from my notebook: people, ideas, triage, the machine with its chimney, and the long arrow back On the left: people. They have ideas, and those come in every shape: a mail, a WhatsApp, a voice message, a screenshot, a sketch on a sheet of paper. Then triage, the funnel. Not everything needs me, and not everything needs me now. Contact reads everything that comes in on the machine in the homelab: my own hardware, boring Debian, offline. It sorts what needs me from what can wait, and groups messages into conversations per person or per topic, whatever app they came from. Fewer apps, less fiddling, but more context and more control. Contact on the laptop, here with sample data: what needs me, drafts, and a conversation with a draft reply waiting Then the machine itself: creation plus context. A session is an agent working on one thing, started from a conversation with one tap. What makes it good is not the model, it is the context it gets. My notes and rules. Every log line of all my apps and computers, well over a million signals a day. The photo library. Customer files and documented source code. The conversation it came from. The machine knows where it stands before it starts. On top sits the chimney: energy, in tokens, compute and memory. This is the part that is new. Context used to be a pile of documents. With enough energy it becomes fluid, you can shape it. Ask it, rewrite it, turn it into a page, a prototype or a print. The chimney, measured: tokens per model I will be honest about the chimney. Some weeks we burn millions of tokens on a single feature, and I do not always know if it was worth it. Let the record show that I spare no cost or effort to chase software feel. But a factory with a chimney and no meter is something to keep an eye on. Out of the machine come artifacts: a draft reply, a preview page, a prototype, a printed puzzle, a website, a game. Nora wanted a game too. She drew a rainbow and told me about a unicorn on a skateboard collecting colours in a fluffy world of clouds, and that became the game. Same factory, different input. Nora's input for her game: a rainbow, clouds and colours to collect Nora playing the game that came out of her drawing Another product of the same factory: the music app, native on iOS and on Android And then the long arrow at the bottom: feedback. Ideas, artifacts and products go back to the people. A draft reply goes back to the customer, after I read it and approve it on my phone; Contact never sends anything by itself. The puzzle went back to the class. What people say about it comes in again on the left, and the loop closes. Not a chat app, not an AI app There are apps for people: Teams, Slack, WhatsApp. There are apps for AI. Contact is neither. It sits between them, on them and in them, at the crossing of people and machine. It is made for making things, and for learning while you do. When it works I hardly notice it: a message comes in, a session picks it up, a draft is waiting when I look. It runs as a native app on the iPhone, the Vision Pro and the laptop, all sharing one idea of what a conversation and a session are. On the Vision Pro the sessions float next to each other, a very nice way to watch several streams of work at once. On the iPhone it is with me all day. A few weeks ago I wrote about making my own Android; that taught me how far you get without touching the operating system, if you own the data, the screens and the concept. Contact is what came out of that lesson. The hardest word When making is cheap and fast, the difficult part is saying no. At one point I asked for my lock screen to show the state of the factory: what waits for me, which session has a question. It was built, I tested it on my phone in the evening, and it worked. I looked at it and decided it was not useful to me. Back to plain notifications, the same evening, nothing left behind. The lock screen experiment: built, tested, and switched off again the same evening My personal reflection helps here. Writing in the notebook makes my norms visible: privacy, the feel of software, and the rule "das Beste oder nichts". That rule leads to "no" quite often. A not-doing choice is a real choice, and now that almost anything can be made, it may be the most important one. Conclusion Contact is a small factory. People and their ideas go in, triage decides what matters, a machine with context and energy makes something, and it goes back to the people. The trick is not the model, it is the context. And the courage to throw away what you made when it is not good enough. So if your inbox feels like a pile of messages, maybe it is a pile of ideas waiting for a factory.
On 11 August I wrote in my notebook: the speed at which we move is about twenty times the old top speed. In one day I do what I used to do in twenty. This post is about that speed, what it does to the human in the loop, and the counterweight I found. It is the first post of September, written on a day of deliberately doing less. Twenty times The number is not a boast, it is a measurement. In August two problems on the cloud were analysed and fixed on the day they appeared, work that used to be a week of digging. It is mentally draining, this speed. Still I find it beautiful, because you shoot with precision and power. Last week was a normal week. A complete restaurant site. A proof of concept for an event venue, promised online within the week. The final touches on a bar site. New sections on two local news sites and a full site for a city square. A site and a members area for a medical publication. Printer support in the shop app, through Apple's review. Analyses of four competitors. A video call setup on the new laptop. And on Sunday evening a prototype for writing by hand, which is how these notes were written. In the same week: three customer visits, two video calls, school runs, football training and a match, a birthday present for my wife built as a little game, a sleepover guest. It is not surprising that we sometimes feel a bit full. Saturday night, 5 September: the terminal on the laptop, one of the sites of the week in the making The human in the loop Mid August, after a week of full throttle, I wrote: I am at my max. Head and body at the limit. The gear worked fantastically, and I was the limiting factor. That is the honest state of things in 2026: the agents do not tire, the logs do not sleep, the builds run at night. The bottleneck has moved, and it moved to me. On a campsite in France I had already written the paradox down: post AI, the challenge is simple to use, less is more. Ship less. A contradiction with agents that can make everything. And the people around you do not always keep up either. The pipelines give you speed, enough to ship at eighty percent and learn. But a customer will look at the breakthrough tomorrow, and a partner needs a week. I have to learn to accept that not everyone switches at light speed. Sometimes that delay is a gift: a quieter period, a little more time for a delivery. The partial eclipse over the trees on 12 August, an evening walk in the busiest week of the month The counterweight The answer I found is not slower agents. It is a routine for the body. We must not see sport as not working: the ideas, the space and the energy are crucial. So there is a shake before the coffee, a run on the odd days, the gym three times a week, and no more finishing the leftovers. A 10K alone on a Friday morning is a relief, clarity of mind through real silence. The best runs of the summer, along the Seine at dawn and on the coast of Brittany, were not fast or strong. They were where the thinking happened. And at the end of August the sharpest note of all: the overload creates the wish for rest and space. That space has to be protected. Sleep matters, and working late at night maybe not. With school, sport and football there is not enough left over to sustain that. I have known this since my first marathon: you can push the limit, but you cannot move it by wanting. The Seine at sunrise on 6 August, the run where the thinking happened The Eiffel tower from below at the turnaround, not fast or strong A marathon, not a sprint Something else happened this week. Sites that generate themselves are becoming common, I see comparable techniques appear around me. The distinguishing factor is no longer the public endpoint, it is the stack behind it: a customer who is happy with the app in her pocket, another who bounces because of his charts. That is much harder to replicate. And there is a harder question still, also for the big AI companies: how do you carry the responsibility of keeping an engine running well, for years? Generating something neat once is easy. Keeping it running, maintaining it, over the long term is another matter. This is a marathon, not a sprint. One of the week's deliveries on the phone: a site for a city square, fresh every day This week So this week we do it differently. Mandatory time for sport and away from the keyboard. A week of rolling out cannot hurt: ninety-nine percent reactive, an empty inbox, and some polish on our own tools. No new websites without a customer's mandate. No customer contact on my initiative. This morning I slept an hour and a half longer and ran five kilometers. The plan had been a half marathon. The body really needed the extra sleep, and I feel a lot better now. The things that are in motion can roll out on their own for a while. Sunday 6 September: sleep 86 percent, recovery 94 percent, strain 0.4, a day off by design Conclusion Twenty times faster is real, and so is the bill. The agents do not tire, I do, and that makes the pace mine to set. A run, a night of sleep and a week of doing less are not a break from the work. They are how the work stays good. Sunday evening: the prototype for writing by hand on the new laptop, these notes were written with it
In August my computer setup changed more than it had in years. And yet the lesson of the month was the opposite of new hardware: the existing gear has stretch, innovation is software. This post is about one brain, the machine in the homelab where my files and my agents live, the machines around it, and why infrastructure has become subordinate to concept. One brain On 2 August, from a campsite in France, I got remote control over the router at home. The plan was to set up a direct connection to the machine in the homelab in Limburg: one brain, one login, one place where files and agents work. Two days later the workshop server that hosted my projects was phased out. Every project moved home, checksum verified, and the homelab took over the full role through a direct mosh link. From the campsite I steered it from my phone, with speech to go faster. That machine in the homelab is the anchor. It holds the platform, the customer projects, the photo library, the backups of the cloud and the agents that work on all of it. The cloud servers run the sites, the agents work from home. Everything else is glass: a screen and a keyboard to look at the brain with. 2 August, from the campsite: a mosh session on the phone into the machine in the homelab, the one brain Logs are readable On 11 August two problems on the cloud, one in mail and one in the web server, were analysed and fixed on the same day. That is only possible through the integration of the anchor in the agentic flow, plus an understanding of the relevant logs and signals. The speed at which we move is about twenty times the old top speed. In one day I do what I used to do in twenty. It is mentally draining, but you shoot with precision and power. The agents do not all live in the cloud. A local model runs on the homelab with no data leaving the house. On 24 August it watched the footage of the doorbell and described, frame by frame, a man walking barefoot to the front door. It was me. Local agents, with access to the network, the files and the protocols, nothing in the way, and a local shell: that is what makes the anchor more than a computer. 24 August: the local model on the homelab describes the doorbell footage frame by frame, no data leaves the house Glass Mid August I watched the introduction of the new Omarchy release. Beautiful work, and the most important features I already had for years: a window manager and integrated tooling. The agent integration is nice, but not fundamentally different from what I do myself. Eye candy is nice, but not a money mover. The existing gear has stretch, innovation is software. Sixteen months ago I explained why I chose a Framework laptop for that gear. So why is there a second Framework on my desk, a twelve inch one? Because of a strict job description. It is not a second brain, it is the agentic workbench: persistent split screens for several agents at once, closed and reopened with one keystroke, and no local computing on it. Glass never becomes anchor. It runs Omarchy, it booted with a green W, and it cost a fraction of the machine it looks at. The Framework 12 open on the table: modular, repairable, and deliberately just glass First boot after setup on 25 August: a green W on the workbench The twin On 22 August I ordered a backup computer and an internet line for Amsterdam. Yes, a fixed line: nine years after the day I killed my LAN and went mobile only, the cable is back, because a machine that receives backups every night needs a connection that is always there. Although I am no fan of clutter, this was a smart step, crucial even, for the data. The anchor has become so important that we must do this. It became a Framework mainboard in a small case with an eight terabyte disk, built on the kitchen floor on 26 August and ready to travel to Amsterdam. From its first night there, the anchor pushes its backups to it. Two houses, two copies, one brain. 26 August, the kitchen floor: the Amsterdam twin being built, a mainboard in a small case with the console on a monitor Infrastructure becomes concept The future? Infrastructure becomes subordinate to concept. Control over routers, devices and connections is scriptable. Logs are readable and concepts are translatable. The artefacts were there before: my own tablet OS on a Surface, the Gran Fondo app. They were not good enough, and I abandoned them. Now it is different, because I can realise things much faster. A custom launcher for my phone, with all its compliance, I would never have built for fun. This month I did. That is the next post. Conclusion One brain, a few pieces of glass and a twin in Amsterdam. The hardware decisions of this month were the small part. The big part is that a machine with agents, logs and a local shell does in a day what used to take weeks, and that the same setup now stands in two houses. Innovation is software. So before you order a faster machine: give the one you have some agents and a look at its logs. It has more stretch than you think, ha! Back at work: the workbench with the mechanical keyboard, the brain out of sight
This month I brought Lemmid Count back: the website statistics of my platform, rebuilt from scratch without AWStats and without a database. Its party piece is the dimension every other analytics tool throws away: the bots. In the agentic era the question "what did AI agents read on my site" matters as much as "how many humans visited". This post is about counting what pretends not to be there, and about putting the answer in your customer's pocket. Google Analytics is blind here Google Analytics works by placing a piece of JavaScript on your pages. A browser runs it, the script reports home, and that report is your statistics. I explained the difference with log-based tools back in 2018. In 2026 that difference has become the whole story. GPTBot, ChatGPT-User, ClaudeBot, PerplexityBot and their friends fetch your HTML and read it. They do not run your JavaScript. They never appear in Analytics. If the agentic web is where your next customers come from, your dashboard is showing you a shrinking world. The web server sees everything. Every request, every user agent, every status code, JavaScript or not. In July my site hartvaat.nl served 114,883 pageviews. 2,187 of them were humans. Analytics would have shown you the 2,187 and called it a quiet month. hartvaat.nl in July 2026: 114,883 pageviews, 2,187 by humans, 112,696 by bots; Analytics would have shown the small number Logs, not scripts Lemmid Count v3 reads the per-site logs of the web server directly, every hour, and folds them into small JSON files per site per day. No database anywhere, no tracking script on the pages, no third party at runtime: the visitor is never touched. That also fixes what killed the previous version: AWStats pumping a near-raw copy of the logs into MariaDB forever. Now the rotated logs are the raw store and the summaries are the product. Two principles. Pages, never people: no visitor counts, no uniqueness tricks, no IP addresses on disk, the browser language instead of geo. And auto configuration: a site with a log file has statistics, nobody has to register anything. Every site on the platform runs along automatically. Classify, do not filter Every request becomes either human or bot, and a bot gets a family and a group: search, ai, social, seo, monitor, feed, lib, scraper. Declared bots are named by their user agent. Instead of filtering them out, Count shows them as first class citizens: a "read by AI agents" card with the agents by name, and a toggle between all, humans and bots. That is new, and it makes people look up. On a restaurant site, in the first days of July, ChatGPT had read 75 pages and Claude 51, next to 185 human pageviews. All, humans or bots: one restaurant site in the first days of July, 185 human pageviews next to 1,171 by bots The humans view: top pages of a cafe site, filtered in one tap The pretenders Labeling is difficult, because some bots pretend to be human. A current Chrome user agent, HTTP/2, a plausible language header, one page per IP address, thousands of addresses from cloud providers. The user agent is worthless there. Behaviour is not. Real browsers load images. Real visitors arrive from search and links, and go to the same popular pages. A crowd that visits thousands of distinct pages, each exactly once, is not a crowd, it is a harvest. Hosting more than a hundred websites is the structural advantage: a signature that shows up on many sites within one hour is not a person. Add honey pots, pages no human would ask for, and address space from datacenters as a hint, never as a verdict. The classifier is versioned, and after every upgrade the last two weeks of history are recomputed. That matters, because the other side moves. One fleet answered a new rule within a day by fetching a single CSS file as an alibi. The next version asked for images. I will not list every signal here, that is the point of a honey pot. Read by AI agents, by name: chatgpt-user, claudebot and the stealth group of pretenders on the same site Full circle: in your pocket Here is the thing: detailed statistics are not unique. Anyone with logs and patience can count. The other half of the job is translating it back into something friendly, pocketable and actionable. Count is an app my customers carry in their pocket, next to the other Lemmid apps: one screen per site, the month in one chart, the top pages, the sources, and the agents by name. No login rituals, no setup, it simply appears for every site you own. The feedback is the best part. A customer showing the stats during the coffee round, exactly the use I had in mind years ago. A cafe owner seeing that ChatGPT read the menu seventy times this month, and drawing the obvious conclusion: put the menu where the agents read it. That is a statistic turned into an action, on a phone, in ten seconds. The pocket app: Manager, Count, Handler, User and Bill, one home screen for every site you own Conclusion The share of humans on the web will keep falling, and a tool that only counts humans will keep telling you the wrong story. Count the agents, name them, and hand the answer to the person who can act on it. High tech in the log parser, low tech on the screen. The bots read. You had better make sure they read the right thing, ha! Midnight on 6 July, the night Count came back, terminal on the iPad
More in technology
Going through a collection of old parts, CuriousMarc encountered some ICs that he couldn't identify. He opened up one of these ICs, and I studied it under the microscope. After some reverse engineering, I determined that it was a logic chip that implemented four NAND gates using old-fashioned diode-transistor logic (DTL).1 The chip turned out to be the ST680A, a member of the Signetics 600 series of chips from 1965. In this article, I discuss the circuitry in this chip and how diode-transistor logic works. The die of the ST680A under the microscope. Integrated circuits can be packaged in many ways. One of the most popular is the plastic DIP (Dual In-line Package), a black rectangle of epoxy with two rows of metal pins. This type of package was invented by Signetics: "Introduced in late 1965, the 600 series was the first integrated circuit family to be offered in a solid, plastic, dual in-line package (DIP)." Earlier integrated circuits were packaged in round metal cans or in small flat-packs. In 1965, engineers at Fairchild invented the DIP, which had two rows of pins on 0.1" spacing. Unlike the surface-mounted flat-pack, the DIP had pins that were inserted into holes, making manual or automated assembly quick and easy. Because the pins of a DIP were on a regular grid, rather than the circular pattern of a metal can, circuit board design and manufacturing were also easier (details). The first DIP chips had ceramic packages. The plastic DIP, introduced by Signetics, was much cheaper and became very popular. An advertisement for the Signetics 600 series. From Electronics, March 21, 1966. The plastic DIP is less popular with me, however, because it is harder to open. With a ceramic package, I can simply tap it with a chisel and pop it open, but that doesn't work with epoxy packages. An epoxy package can be dissolved with nitric or sulfuric acid, but I try to avoid dangerous acids. Instead, CuriousMarc used Antoine's hot air decapping method. Unfortunately, the hot air technique doesn't always work. In this case, tiny bits of epoxy were stuck to the die, obscuring the circuitry. I used a few drops of boiling sulfuric acid to clean the die. (I'm okay with sulfuric acid in tiny quantities.) The die on its metal frame. The photo above shows the silicon die on its metal frame, the lead frame. The golden blobs are where the bond wires were attached to the die. You can see the doped silicon regions that form diodes and bipolar NPN transistors, as well as 16 resistors in the center, forming serpentine paths. Most chips have a passivation layer—a thin layer of silicon dioxide—over the chip. Inconveniently, this old chip didn't have a passivation layer, so the acid also stripped off the metal layer. (A few remnants are visible in the upper left.) Without the metal layer, I had to guess at how the components were connected to form logic gates. The die has very faint color differences where the silicon was protected by the metal, so that helped. Eventually, I came up with the diagram below, showing how the metal layer was probably configured. This wiring reveals that the chip implements four DTL NAND gates, which I'll describe in more detail below. One puzzle was that the chip has two unused diodes, indicated with question marks below. The metal layer for a quad NAND chip. I desaturated the image to make the labels clearer. Transistors, diodes, and resistors In this section, I'll explain how the patterns in the image correspond to components of the circuit. The silicon die is doped with various impurities to form regions with different electrical characteristics. These regions appear red or green under the microscope due to thin-film effects. As a result, the chip's transistors, diodes, and resistors are visible. The chip is made from bipolar NPN transistors, which have a completely different construction from the MOS transistors in modern ICs. In an NPN transistor, the current from the collector to the emitter is controlled by the current through the base. The collector is a large region of N-type silicon, silicon that is doped with atoms such as phosphorus or arsenic. Since these elements have one more valence electron than silicon, they give the silicon more negative charge carriers, so it is called N for negative. The N-type silicon happens to appear reddish. On top of the collector, the base is a thin region of P-type silicon, which appears green. This silicon has been doped with atoms such as boron or gallium, which have one fewer valence electron than silicon. The missing electrons form "holes", which act as positive charge carriers. Finally, the emitter is N-type silicon, on top of the base layer. These layers work together through semiconductor magic, amplifying the base current. Two NPN transistors on the chip. The second transistor is a larger output transistor. The chip's output transistors are slightly larger so they can sink more current. In the transistor on the right above, note that the collector contact wraps around three sides of the transistor. The emitter is also larger, with an L-shaped contact. According to the datasheet, each output transistor can sink 2.5 mA of current. The chip uses many diodes since it is diode-transistor logic. The structure of a diode is similar to a transistor, but without the emitter. In a diode, current flows from the cathode (P-type silicon) to the anode (N-type). A diode and a resistor on the chip. The chip uses 16 resistors, located in the middle of the die. A resistor is constructed from a long, thin region of doped silicon. Since silicon has moderately high resistance, a long strip of silicon acts as a resistor. Most of the resistors have a serpentine layout to fit a long resistor into a smaller area. These resistors consist of P-type silicon (green) in a "tub" of N-type silicon (red). The tub is connected to the positive voltage supply; since current doesn't flow from N-type silicon to P-type silicon, this isolates the resistors from each other. Operation of a DTL gate Logic gates can be created in many ways. The earliest integrated circuits (such as the ones in the Apollo Guidance Computer) used Resistor-Transistor Logic (RTL), where logic gates were constructed from resistors and transistors. In March 1962, Signetics announced the first family of commercial Diode-Transistor Logic (DTL) integrated circuits (details). By using diodes on the inputs instead of resistors, DTL provided better performance than RTL. However, DTL soon became overshadowed by TTL (Transistor-Transistor Logic), which was faster and used less power. (If you built digital circuits a few decades ago, you're probably familiar with the popular 7400 series of TTL chips.) The diagram below shows how the DTL NAND gate works. If both inputs are high, the current from the first resistor flows through the base of the first transistor, turning it on. The transistor amplifies this current, passing a much larger current from the transistor's collector to the transistor's emitter. This current goes through the base of the second transistor, which turns on the second transistor. The second transistor passes an even larger current from the output pin to ground, pulling the output pin low. The DTL NAND gate with both inputs high. The schematic is from the datasheet. This circuit is considerably more complicated than the DTL gate on Wikipedia. But if one of the input pins is pulled low, the current from the resistor goes through the diode instead of the transistor. The first transistor turns off, and without a base current, the second transistor turns off. The third resistor pulls the output high. Thus, the output is low only if both inputs are high: a NAND gate. The DTL NAND gate with an input low. I'll point out a few features of this circuit. The diodes on the inputs ensure that one input doesn't affect the other input. The diode in the middle raises the voltage on the first transistor's emitter, so it requires more voltage to turn on, reducing the sensitivity to noise. The output uses a resistor to pull the output high; more advanced circuits use another transistor. When the output is low, the third resistor is still "trying" to pull the output high, which is wasting power. Moreover, the resistor limits the output current, so the high output is fairly weak. In some DTL families, you can get gates with different values for the output resistor, so you can select the tradeoff between wasting power and having an output that is too weak. If you've used TTL integrated circuits from the 1970s, you know that chips usually have power and ground on diagonal pins: ground on pin 7 and power on pin 14. (Putting power and ground diagonally opposite both helps die layout and circuit board layout.) Much to my surprise, I found that the Signetics chips predate this standard and have ground on pin 1 and power on pin 8: still diagonal, but the wrong diagonal! The diagram below shows how the four NAND gates are wired in the chip. Pinout of the 680A quad NAND gate. From the databook. Three chips from one die When I examined the die under the microscope, I figured out the circuit, but I was puzzled by two extra diodes, as if two NAND gates had a third input that wasn't used. The explanation is that Signetics used the same silicon layout for at least three different chips, applying a different metal layer for different functionality. This saved money since it's much cheaper to produce a single optical mask for the metal layer than a complete set of new masks. Signetics sold semi-custom ICs to customers, using an approach called variFEBS (Variable Functional Electronics Blocks). This approach used a custom metal layer on top of fixed silicon, providing custom circuits without the cost of a full mask set. These circuits didn't sell well, but Signetics used the same approach for standard ICs. Pinout of the 670A triple NAND gate and the 616A quad NAND gate. All three chips have some similarities, such as using pins 2 and 14 as outputs. From the databook. One IC with the same silicon as the quad NAND gate is the 670A chip, which has three NAND gates, each with three inputs (above left). The diagram below shows how the silicon can be wired to provide this functionality. The hypothesized metal layer for the 670A triple-NAND gate. The layout for the triple chip above is a bit tricky because the top gate has inputs on both sides of the power (Vcc) pin. This creates a layout problem because the power and ground metal runs vertically to the resistors, blocking metal wiring from one side to the other. The solution is a "crossunder", a region of silicon that allows a signal to pass under the metal layer, connecting the inputs on the left to the rest of the circuitry on the right. This crossunder is visible near the top of the chip. Another chip with the same layout is the 616A dual NAND gate, with five inputs on each gate. Since this chip has 10 inputs in total (compared to 8 on the quad gate), this chip uses the two "extra" diodes that I spotted. If that isn't enough inputs, each NAND gate has an expansion input; by connecting external diodes to the expansion input, the gate can be made as large as desired. The hypothesized metal layer for the 616A dual-NAND chip. Some history The history of Signetics is closely tied to Fairchild. The story of Fairchild's founding is well known: in 1957, eight engineers—the Traitorous Eight—left Shockley Semiconductor and created Fairchild Semiconductor. Hundreds of companies (the "Fairchildren") were started by engineers who left Fairchild. Signetics was one of those companies, formed in 1961 and said to be the first company to exclusively design and manufacture integrated circuits.2 Signetics announced its first product in 1962, a NAND gate that cost $125 (over $1000 in current dollars).3 Not surprisingly, sales were weak. Signetics soon ran short of money, so in 1962, Corning Glass invested $1.7 million for 51% ownership of Signetics. Corning Glass may seem like a strange investor, but Corning was more of a high-tech company than you'd expect, making components such as resistors and glass capacitors, and later creating fiber optics. Moreover, in the early 1960s, integrated circuits were the hot area (much like AI now), and everyone wanted to get involved. In 1963, the Department of Defense pushed for contractors to use integrated circuits in new products. Riding this wave, Signetics became the leading producer of integrated circuits.4 However, Fairchild soon introduced a series of DTL chips that competed with Signetics. The Fairchild 930 series was faster than the Signetics chips and less than half the price, so Fairchild took much of the market from Signetics and dominated the IC market. Signetics also produced analog integrated circuits. Signetics is probably best known for creating the 555 timer chip in 1970, said to be the world's most popular IC, with billions sold.5 Signetics was acquired by Philips in 1975, and then Philips Semiconductors was spun off as NXP (Next exPerience) in 2006. NXP is currently the #10 semiconductor manufacturer worldwide, so the heritage of Signetics lives on. For more, follow me on Bluesky (@righto.com), Mastodon (@[email protected]), or RSS. Thanks to CuriousMarc for providing the IC and thanks to TubeTime for finding the databook. AI statement: Despite the presence of the em dash, no AI was used in the writing of this article (details). Notes and references After I had reverse-engineered the chip, TubeTime found datasheets for it, making my reverse engineering unnecessary. (See the Signetics Condensed Catalog 1969, Utilogic II Databook 1971, and Utilogic 2 Databook 1972.) We must have been unlucky with our original web searches since we didn't find anything. But this way you get to see what's inside the chip :-) The Signetics ST680A IC in its package. The large circular depression marks pin 1. From the date code, this chip is from 1971. ↩ For more Signetics history, see Signetics Founding History, written by Lionel Kattner, a co-founder of Signetics. He states that the company name was inspired by the words "signals" and "networks", as well as the high-tech suffix "-netics". ↩ See History of Semiconductor Engineering, page 156. ↩ The book Making Silicon Valley describes the history of Signetics. It has a negative view of the Corning investment, saying that Signetics executives "Van Poppelen and Kattner dissented on the grounds that Corning was not a good fit for an integrated circuit company. In their view, Corning was a staid Eastern firm, ignorant about semiconductors and antithetic to the ways and culture of the electronics industry on the West Coast. Their view later proved to be correct." ↩ The 555 timer was created by analog IC wizard Hans Camenzind. If you're interested in analog circuits, you should read his book Designing Analog Chips, which you can download for free. ↩
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