It’s Not Easy Counting Transistors In The 8086 Processor

For any given processor it’s generally easy to find a statistic on the number of transistors used to construct it, with the famous Intel 8086 CPU generally said to contain 29,000 transistors. This is where [Ken Shirriff] ran into an issue when he sat down one day and started counting individual transistors in die shots of this processor. To his dismay, he came to a total of 19,618, meaning that 9,382 transistors are somehow unaccounted for. What is going on here?

The first point here is that the given number includes so-called ‘potential transistors’. Within a section of read-only memory (ROM), a ‘0’ would be a missing transistor, but depending on the programming of the mask ROM (e.g. for microcode as with a CISC x86 CPU), there can  be a transistor there. When adding up the potential but vacant transistor locations in ROM and PLA (programmable logic array) sections, the final count came to 29,277 potential transistors. This is much closer to the no doubt nicely rounded number of 29,000 that is generally used.

[Ken] also notes that further complications here are features such as driver transistors that are commonly found near bond wire pads. In order to increase the current that can be provided or sunk by a pad, multiple transistors can be grouped together to form a singular driver as in the above image. Meanwhile yet other transistors are used as (input protection) diodes or even resistors. All of which makes the transistor count along with the process node used useful primarily as indication for the physical size and complexity of a processor.

A sequence of pictures with arrows between each other. This picture shows a Wokwi (Fritzing-like) diagram with logic gates, going to a chip shot, going to a panel of chipsGA footprint on a KiCad PCB render with DIP switches and LEDs around the breakout. Under the sequence, it says: "Tiny Tapeout! Demystifying microchip design and manufacture"

Design Your Own Chip With TinyTapeout

When hackers found and developed ways to order PCBs on the cheap, it revolutionized the way we create. Accessible 3D printing brought us entire new areas to create things. [Matt Venn] is one of the people at the forefront of hackers designing our own silicon, and we’ve covered plenty of his research over the years. His latest effort to involve the hacker community, TinyTapeout, makes chip design accessible to newcomers – the bar is as low as arranging logic gates on a web browser page.

Six chip shots shown, with various densities of gates being used - some use a little, and some use a the entire area given.
Just six of the designs submitted, with varying complexity

For this, [Matt] worked with people like [Uri Shaked] of Wokwi fame, [Sylvain “tnt” Munaut], [jix], and a few others. Together, they created all the tooling necessary, and most importantly, a pipeline where your logic gate-based design in Wokwi gets compiled into a block ready to be put into silicon, with even simulations and compile-time verification for common mistakes. As a result, the design process is remarkably straightforward, to the point where a 9-year-old kid can do it. If you wanted, you could submit your Verilog, too!

The first round of TinyTapeout had a deadline in the first days of September and brought 152 entries together – just in time for an Efabless shuttle submission. All of these designs were put on a single instance of a chip, that will be fabbed in quantity, tested, soldered onto breakouts, and mailed out to individual participants. In this way, everyone will be getting everyone’s design, but thanks to the on-chip muxing hardware, they’re able to switch between designs using on-breakout DIP switches.

More after the break…

Continue reading “Design Your Own Chip With TinyTapeout”

The Open Source ASICs Hack Chat Redefines Possible

There was a time when all that was available to the electronics hobbyist were passive components and vacuum tubes. Then along comes the integrated circuit, and it changed everything. Fast forward a bit, and affordable programmable microcontrollers arrived on the scene. Getting started in electronics became far easier, and the line between hardware and software started to blur. Much more recently, the hobbyist community was introduced to field programmable gate arrays (FPGAs) and the tools necessary to work with them. While not as widely applicable as the IC or MCU, the proliferation of FPGAs among hardware hackers once again opened doors that were previously locked tight.

We’re currently on the edge of another paradigm shift, but it’s no surprise if you haven’t heard of it. After all, the last couple of years have been a bit unusual, so the 2020 announcement that Google was teaming up with SkyWater and Efabless to enable the design and manufacture of open source application-specific integrated circuits (ASICs) flew under the radar for many people. But not Matt Venn, the host of this week’s Hack Chat. For him, it was the opportunity he’d been waiting for.

Matt started like many of us, building electronic kits and building new gadgets out of old discarded hardware. He graduated to microcontrollers, and became particularly interested in FPGAs when the open source toolchains started hitting the scene. Of course by this point, it was much more than just a hobby for him. He was presenting a talk at the 2019 Week of Open Source Hardware in Switzerland when he saw Tim Edwards from Efabless demo a chip that had been made with open source tools. Unfortunately, the costs involved were still far too high for an individual to put their ideas into silicon.

So when Google and Skywater announced they would be footing the bill to have selected open source ASIC designs manufactured a few months later, Matt says he was in a good position to jump in. He has since started running the Zero to ASIC Course which aims to teach you how to produce your own chips using the open source Process Development Kit, and so far 160 people have taken him up on the offer.

As you might expect, many of the questions in the Chat had to do with what kind of designs you can actually produce using the 130 nm process. Especially given the limits on the physical space each creator’s circuit can take up on each multi-project wafer (MPW). Others wanted to know how difficult it would be to port over existing FPGA designs, or how well the process worked with analog applications. With the number of designs Matt has seen go through his course, he could answer many of the questions just by pointing to a particular individual’s ASIC. For instance, he held up the digital-to-analog converter from Harald Pretl and Thomas Parry’s 5 GHz satellite transceiver as prime analog examples.

So let’s say you put the work in to design an ASIC and it gets approved to be produced on a future MPW, what then? Well, first you have to hope everything goes according to plan. Matt explains that the initial run was almost a total write-off due to timing problems in the toolchain, though in the end, he was largely able to recover his own chip. But they’ve done several runs since then, so let’s assume there’s no production problems. What exactly ends up on your doorstep?

If you were expecting a handy DIP8, you might be disappointed. While some DIY friendly packages would be nice, right now the ASICs ship as wafer level chip scale package (WLCSP) with an unforgiving 0.5 mm pitch. If you can believe it, that’s actually an improvement over the first run, which shipped out as a bare die. Of course as Matt pointed out, anyone who’s gotten to the point of designing their own custom ASIC probably won’t be scared off by the prospect of some fine-pitch soldering. Some in the Chat wondered about the difficulty in getting compatible PCBs produced, but Matt said that in his experience OSH Park has been up to the challenge.

Like the Metal 3D Printing Hack Chat before it, this week’s session went over a topic that’s on the absolute cutting edge of what’s possible for hardware hackers and hobbyists. Truth be told, the vast majority of the people reading Hackaday are no more likely to send away for their own custom ASIC as they are to battle x-rays in an attempt to sinter metal with a homebrew electron gun. But that doesn’t make the fact that some folks out there doing it any less important, or inspiring. That said, if you do end up being one of those select few that can boast they’ve designed a custom chip of their own — don’t forget to send one of them our way.

We’re grateful Matt Venn was able, once again, to share his valuable experience in the realm of open source application-specific integrated circuits with us. If you haven’t checked them out already, the Zero to ASIC workshop he ran for Remoticon 2020 and his talk Open Source ASICs – A Year in Perspective from Remoticon 2021 are required viewing if you want to learn more about this fascinating new frontier in hardware hacking.


The Hack Chat is a weekly online chat session hosted by leading experts from all corners of the hardware hacking universe. It’s a great way for hackers connect in a fun and informal way, but if you can’t make it live, these overview posts as well as the transcripts posted to Hackaday.io make sure you don’t miss out.

Al Williams Tells All In The Logic Simulation Hack Chat

The list of requirements for hosting one of our weekly Hack Chats is pretty short: you’ve got to be knowledgeable, passionate, and above all else, willing to put those two quantities on display for a group of like-minded strangers. Beyond that, we’re not too picky. From industry insider to weekend hobbyist, high school dropout to double doctorate, if you’ve got something interesting to talk about, we’re ready to listen.

But in casting a such a wide net, we occasionally forget that we’ve got a considerable collection of potential hosts within our own worldwide roster of contributors. Among this cast of characters, few can boast the same incredible body of knowledge as Al Williams, who was able to pencil in some time this week to host the Logic Simulation Hack Chat.

Or at least, that was the idea. In reality the Chat covered a wide range of topics, and was peppered with fascinating anecdotes pulled from Al’s decades of experience in the field. Though to be fair, we expected no less. He was building hardware before many of us were born, and can take credit for designs that have been at the bottom of the ocean as well as launched into orbit. He’s been writing about it just as long too, with articles of his appearing in iconic print magazines such as Dr. Dobb’s Journal.

Al has seen and done so much that he still surprises us with the occasional nugget, and we’ve been working with him for years. It was only a week or two back that he started a story with “Back when I used to manage a gas pipeline…” in the middle of a conversation about utility metering.

Of course, that’s not to say some technical discussion didn’t sneak in there from time to time. Sure Al’s  recollection of how they used to literally crawl over the schematics for the 68000 back at Motorola might stick out as a particular high point, but he also explains his personal preference for vendor-specific software tools over their more generic open source counterparts. He also draws comparisons between hardware description languages (HDLs) like Verilog and parametric CAD tools such as OpenSCAD in the way that they help model complex relationships in ways that can’t be easily done by more traditional means.

At one point the conversation lingers on the design and production of application-specific integrated circuits (ASICs), and how they compare to field-programmable gate arrays (FPGAs). Traditionally ASICs have been out of reach for the hobbyist, but with the recent collaboration between Google and SkyWater Technology to create an open source process design kit (PDK), they’re now within the capabilities of a dedicated individual. Matt Venn spoke on the topic during Remoticon 2021, and it’s good to see more folks in the community openly discussing the possibilities of custom silicon designed by hackers.

From there, things start really getting wild. From dreaming of virtual reality circuit simulators that let you fly amongst your creations like in Tron, to salivating over high-end technologies such as reflective memory, this Chat really runs the gamut. But then, that’s sort of why we hold them in the first place. Whether you actively participate or are just along for the ride, the Hack Chat gives everyone in the community a chance to gather around a virtual water cooler with fascinating characters that you won’t find anywhere else.


The Hack Chat is a weekly online chat session hosted by leading experts from all corners of the hardware hacking universe. It’s a great way for hackers connect in a fun and informal way, but if you can’t make it live, these overview posts as well as the transcripts posted to Hackaday.io make sure you don’t miss out.

Remoticon 2021 // Matt Venn Helps You Make ASICS

What would you make if you were given about ten square millimeters of space on a silicon wafer on a 130 nm process? That’s the exact question that the Open MPW program asks, and that [Matt Venn] has stepped up to answer. [Matt] came to Remoticon in 2020 to talk about his journey from nothing to his own ASIC, and he came back in 2021 to talk about what has happened in a year.

image of the metal layers of an IC
[maxiborga] has been making beautiful renders of his and others’ chip designs
We expected great designs, but the variety of exciting and wonderful designs that have been submitted we think exceeded our expectations. [Matt] goes through quite a few of them, such as an analog neuron, a RISC-V Arduino-compatible microprocessor, and a satellite transceiver. Perhaps an unexpected side effect has been the artwork. Since the designs are not under an NDA, anyone can take the design and transform it into something gorgeous.

Of course, all of this hardware design isn’t possible without an open toolchain. There is an SRAM generator known as OpenRAM that can generate RAM blocks for your design. Coriolis2 is an RTL to GDS tool that can do placement and routing in VLSI. Finally, FlexCell is a cell library that tries to provide standard functions in a flexible, customizable way that cuts down on the complexity of the layout. There are GitHub actions that can run tests and simulations on PRs to keep the chip’s HDL in a good state.

However, it’s not all roses, and there was an error on the first run (MPW1). Hold time violations were not detected, and the clock tree wasn’t correct. This means that the GPIO cannot be set up, so the designs in the middle could be working, but without the GPIO, it is tricky to determine. With a regular chip, that would be the end, but since [Matt] has access to both the layout and the design, he can identify the problem and come up with a plan. He’s planning on overriding the IO setup shift register with an auxiliary microcontroller. (Ed Note: [tnt] has been making some serious progress lately, summarized in this video.)

It is incredible to see what has come from the project so far, and we’re looking forward to future runs. If this convinces you that you need to get your own ASIC made, you should check out [Matt]’s “Zero to ASIC” course.

Continue reading “Remoticon 2021 // Matt Venn Helps You Make ASICS”

NTP server heated with Bitcoin mining dongles

Bitcoin Mining ASICs Repurposed To Keep NTP Server On Track

They say time is money, but if that’s true, money must also be time. It’s all figurative, of course, but in the case of this NTP server heater powered by Bitcoin mining dongles, money actually does become time.

This is an example of the lengths to which Network Time Protocol aficionados will go in search of slightly better performance from their NTP servers. [Folkert van Heusden], having heard that thermal stability keeps NTP servers happy, used a picnic cooler as an environmental chamber for his  Pi- and GPS-based NTP rig. Heat is added to the chamber thanks to seven Block Erupter ASIC miner dongles, which are turned on by a Python script when a microcontroller sends an MQTT message that the temperature has dropped below the setpoint.

Each dongle produces about 2.5 Watts of heat when it’s working, making them pretty effective heaters. Alas, heat is all they produce at the moment — [Folkert] just has them working on the same hash over and over. He does say that he has plans to let the miners do useful work at some point, not so much for profit but to at least help out the network a bit.

This seems like a bit of a long way around to solve this problem, but since the mining dongles are basically obsolete now — we talked about them way back in 2013 — it has a nice hacky feeling to it that we appreciate.

Using VHDL To Generate Discrete Logic PCB Designs

VHDL and Verilog are hardware description languages, used to describe and define logic circuits. They’re typically used to design ASICs and to program FPGAs, essentially using software to define hardware. However, [Tim] has done something altogether quite creative, creating tools to take VHDL and Verilog and spit out PCB designs for discrete logic. 

Yes, you read that correctly. The basic idea is to take VHDL source code, and then make a PCB layout that implements the desired logic using resistor-transistor logic. From there, the PCB design files can be shipped off to a manufacturer for pick-and-place assembly at a fraction of the cost of producing a bespoke ASIC.

The drawbacks are obvious; tons of individual discrete parts are required, the size penalty is hilariously bad, and power usage is almost certainly orders of magnitude higher than doing the same logic on an ASIC or even FPGA. Oh, and everything’s much slower, too.

However, as an academic exercise or simply for fun, it’s an awesome bit of work. The idea that one can define a complicated logic circuit and have a PCB implementing the logic whipped up by automated tools is amazing, and we absolutely want to see more of this type of thing.

We’ve seen similar work done with VHDL synthesis into 74-series logic design. If you’ve been developing your own fancy digital-logic-fu, be sure to drop us a line!

[Thanks to Yann Guidon for the tip!]