Integrated Circuits Can Be Easy To Understand With The Right Teachers

For years I’ve been trying to wrap my mind around how silicon chips actually work. How does a purposefully contaminated shard of glass wield control over electrons? Every once in a while, someone comes up with a learning aid that makes these abstract concepts really easy to understand, and this was the case with one of the booths at Maker Faire Bay Area. In addition to the insight it gave me (and hundreds of Faire-goers), here is an example of the best of what Maker Faire stands for. You’ll find a video of their presentation embedded below, along with closeup images of the props used at the booth.

The Uncovering the Silicon booth had a banner and a tablecloth, but was otherwise so unassuming that many people I spoke with missed it. Windell Oskay, Lenore Edman, Eric Schlepfer, John McMaster, and Ken Shirriff took a 50-year-old logic chip and laid it bare for anyone who cared to stop and ask what was on display. The Fairchild μL914 is a dual NOR gate, and it’s age matters because the silicon is not just simple, it’s enormous by today’s standards making it relatively easy to peer inside with tools available to the individual hacker.

ATmega328 decapped by John McMaster was also on display at this booth

The first challenge is just getting to the die itself. This is John McMaster’s specialty, and you’re likely familiar from his Silicon Pr0n website. He decapped the chip (as well as an ATmega328 which was running the Arduino blink sketch with it’s silicon exposed). Visitors to the booth could look through the microscope and see the circuit for themselves. But looking doesn’t mean understanding, and that’s where this exhibit shines.

To walk us through how this chip works, a stack-up of laser-cut acrylic demonstrates the base, emitter, and collector of a single transistor. The color coding and shape of this small model makes it easy to pick out the six transistors of the 941 on a full model of the chip. This lets you begin to trace out the function of the circuit.

For me, a real ah-ha moment was the resistors in the design. A resistive layer is produced by doping the semiconductor with impurities, making it conduct more poorly. But how do you zero-in on the desired resistance for each part? It’s not by changing the doping, that remains the same. The trick is to make the resistor itself take up a larger footprint. More physical space for the electrons to travel means a lower resistance, and in the model you can see a nice fat resistor in the lower right. The proof for these models was the final showpiece of the exhibit as the artwork of the silicon die was laid out as a circuit board with discrete transistors used to recreate the functionality of the original chip.

Windell takes us through the booth presentation in the video below. I think you’ll be impressed by the breakdown of these concepts and how well they aid in understanding. This was a brilliant concept for an exhibit; it brought together interdisciplinary experts whom I respect and whose work I follow, and sought to invite everyone to gain a better understanding of the secrets hiding in the chips that underpin this technological age. This is exactly the kind of thing I love to see at a Maker Faire.

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Ken Shirriff Chats About A Whole World Of Chip Decapping

Reverse engineering silicon is a dark art, and when you’re just starting off it’s best to stick to the lesser incantations, curses, and hexes. Hackaday caught up with Ken Shirriff at last year’s Supercon for a chat about the chip decapping and reverse engineering scene. His suggestion is to start with an old friend: the 555 timer.

Ken is well-known for his work photographing the silicon die at the heart of an Integrated Circuit (IC) and mapping out the structures to create a schematic of the circuit. We’re looking forward to Ken’s talk in just a few weeks at the Hackaday Superconference. Get a taste of it in the interview video below.

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Retrotechtacular: AM Radios, Core Memory, And Color TV, What Was Hot In Chips In ’73

As part of writing tech stories such as those we feature here at Hackaday, there is a huge amount of research to be done.  We trawl through pages and pages of obscure blogs, videos, and data sheets. Sometimes we turn up resources interesting enough that we file them away, convinced that they contain the nucleus of another story at some point in the future.

Today’s topic of entertainment is just such a resource, courtesy of the Internet Archive. It’s not a video as we’d often provide you in a Retrotechtacular piece, instead it’s the February 1973 edition of the Fairchild Semiconductor Linear Integrated Circuits Catalog. Books like this one that could be had from company sales representatives were highly prized in the days before universal Internet access to data sheets, and the ink-on-paper datasheets within it provide a fascinating snapshot of the integrated electronics industry as it was 45 years ago.

The first obvious difference between then and now is one of scale, this is a single volume containing Fairchild’s entire range. At 548 pages it wouldn’t have been a slim volume by any means, but given that Fairchild were at the time one of the big players in the field it is unimaginable that the entire range of a 2018 equivalent manufacturer could be contained in the same way. Given that the integrated circuit was at the time an invention barely 15 years old, we are looking at an industry still in relative infancy.

The catalog has a series of sections with familiar headings: Operational amplifiers, comparators, voltage regulators, computer/interface, consumer, and transistor/diode arrays with analog switches. Any modern catalog will have similar headings, and there are even a few devices you will find have survived the decades. The μA741 op-amp (page 64) from its original manufacturer has not yet become a commodity product here, and it sits alongside familiar devices such as the μA7800 series (page 201) or μA723 (page 194) regulators.

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The Art Of The Silicon Chip

If you have followed the group of reverse engineers whose work on classic pieces of silicon we feature regularly here at Hackaday, you may well be familiar with the appearance of the various components that make up their gates and other functions. What you may not be familiar with, however, are the features that can occasionally be found which have no function other than the private amusement of the chip designers themselves. Alongside the transistors, resistors, and interconnects, there are sometimes little pieces of artwork inserted into unused spaces on the die, visible only to those fortunate enough to own a powerful microscope.

Fortunately those of us without such an instrument can also take a look at these works, thanks to the Smithsonian Institution, who have brought together a gallery of them on the web as part of their chip collection. In it we find cartoon characters such as Dilbert, favourites from children’s books such as Waldo, and the Japanese monster Godzilla. There are animals, cows, a leopard, a camel, and a porpoise, and of course company logos aplenty.

In a sense, these minuscule artworks are what our more strident commenters might describe as Not A Hack, but to dismiss them in such a manner would be to miss their point. Even in an age of huge teams of integrated circuit designers working with computerized tools rather than the lone geniuses of old with their hand drafting, we can still see little flashes of individuality with no practical or commercial purpose and with no audience except a very few. And we like that.

Also take a look at the work of [Ken Shirriff] for a masterclass in IC reverse engineering.

Project 54/74 Maps Out Logic ICs

Integrated circuits are a fundamental part of almost all modern electronics, yet they closely resemble the proverbial “black box” – we may understand the inputs and outputs, but how many of us truly understand what goes on inside? Over the years, the process of decapping ICs has become popular – the removal of the package to enable peeping eyes to glimpse the mysteries inside. It’s an art that requires mastery of chemistry, microscopy and photography on top of the usual physics skills needed to understand electronics. Done properly, it allows an astute mind to reverse engineer the workings of the silicon inside.

There are many out there publishing images of chips they’ve decapped, but [Robert Baruch] wants more. Namely, [Robert] seeks to create a database of die images of all 5400 and 7400 series logic chips – the eponymous Project 54/74.

These chips are the basic building blocks of digital logic – NAND gates, inverters, shift registers, decade counters and more. You can build a CPU with this stuff. These days, you may not be using these chips as often in a production context, but those of you with EE degrees will likely have toyed around a few of these in your early logic classes.

There’s only a handful of images up so far, but they’re of excellent quality, and they’re also annotated. This is a great aid if you’re trying to get to grips with the vagaries of chip design. [Robert] is putting in the hard yards to image as many variations of every chip as possible. There’s also the possibility of comparing the same chip for differences between manufacturers. We particularly like this project, as all too often manufacturing techniques and technologies are lost and forgotten as the march of progress continues on. It looks like it’s going to become a great resource for those looking to learn more about integrated circuit design and manufacture!

Georgia Tech Pumps Water Through Silicon For Chip Cooling

One of the things that stops electronic devices from going faster is heat. That’s why enthusiasts go as far as using liquid nitrogen to cool CPU chips to maximize their overclocking potential. Researchers at Georgia Tech have been working on cutting fluid channels directly into the back of commercial silicon die (an Altera FPGA, to be exact). The tiny channels measure about 100 micron and are resealed with another layer of silicon. Water is pumped into the channels to cool the device efficiently.

A comparable air-cooled device would operate at about 60 degrees Celsius. With the water cooling channels cut into the die and 20 degree water pumped at 147 ml/minute, the researchers kept the chip operating about less than 24 degrees Celsius.

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