Universal Chip Analyzer: Test Old CPUs In Seconds

April 11, 2018 by Ben James 40 Comments

Collecting old CPUs and firing them up again is all the rage these days, but how do you know if they will work? For many of these ICs, which ceased production decades ago, sorting the good stuff from the defective and counterfeit is a minefield.

Testing old chips is a challenge in itself. Even if you can find the right motherboard, the slim chances of escaping the effect of time on the components (in particular, capacitor and EEPROM degradation) make a reliable test setup hard to come by.

Enter [Samuel], and the Universal Chip Analyzer (UCA). Using an FPGA to emulate the motherboard, it means the experience of testing an IC takes just a matter of seconds. Why an FPGA? Microcontrollers are simply too slow to get a full speed interface to the CPU, even one from the ’80s.

So, how does it actually test? Synthesized inside the FPGA is everything the CPU needs from the motherboard to make it tick, including ROM, RAM, bus controllers, clock generation and interrupt handling. Many testing frequencies are supported (which is helpful for spotting fakes), and if connected to a computer via USB, the UCA can check power consumption, and even benchmark the chip. We can’t begin to detail the amount of thought that’s gone into the design here, from auto-detecting data bus width to the sheer amount of models supported, but you can read more technical details here.

The Mojo v3 FPGA development board was chosen as the heart of the project, featuring an ATmega32U4 and Xilinx Spartan 6 FPGA. The wily among you will have already spotted a problem – the voltage levels used by early CPUs vary greatly (as high as 15V for an Intel 4004). [Samuel]’s ingenious solution to keep the cost down is a shield for each IC family – each with its own voltage converter.

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Hackaday Prize Entry: The Minimalist Z80 Computer

October 26, 2017 by Brian Benchoff 22 Comments

The best projects always seem to come from eBay. A few weeks ago, we found a few tiles meant for gigantic LED panel installations, and fifty bucks got you ten tiles. That eBay auction is now sold out. A while ago, [Just4Fun] realized he could build a Z80 microcomputer with $4 worth of parts from everyone’s favorite online auction house. The result is a $4 Z80 home computer, and a great Hackaday Prize entry to boot.

So, what do he need to build a retrocomputer loaded up with Forth, CP/M, and Basic? A CPU is a necessity, and [Just4Fun] found a Z80 (technically a Z84C00) for just a bit more than a dollar. A computer will need some RAM too, and a 128 kiB parallel SRAM was just the ticket for another dollar.

Here’s where things get a bit more interesting. Where the retrocomputers of yore were loaded up with glue logic, PLAs, or other weird chips, modern technology has come a long way. Instead of a massive amount of glue, [Just4Fun] is using an ATmega32A for all the I/O, address decoding, and a serial terminal.

The ATmega thrown into this cornucopia of vintage chips is itself more than a decade old, but it does have 40 pins and 32 kiB of Flash. That’s enough to ‘virtualize’ all the peripherals you’d need on a Z80 bus and provide the clock signal for the rest of the computer.

This home computer was originally designed and laid out on a solderless breadboard, but [WestfW] managed to stuff this all onto a small PCB. That’s a cheap computer that gets you all the retrocomputing goodies, and it’s something that’s just random enough to be a perfect entry for the Anything Goes portion of the Hackaday Prize.

The 1980s Called – Asking For The Z80 Membership Card

September 15, 2017 by Anool Mahidharia 36 Comments

The ’80’s and early ’90’s saw a huge proliferation of “personal” computers, spawning an army of hacker kids who would go on to hone their computing chops on 8-bit and 16-bit computers from brands such as Sinclair, Commodore, Acorn, Apple, Atari, Tandy/RadioShack and Texas Instruments. Fast forward to 2017, and Raspberry-Pi, BeagleBone and micro:bit computers reign supreme. But the old 8-bit and 16-bit computer systems can still teach us a lot.

[Lee Hart] has built the amazing Z80 Membership Card — a Z80 computer that fits in an Altoids tin. His design uses generic through hole parts mounted on a PCB with large pads, thick tracks and lots of track clearances, making assembly easy. Add to this his detailed documentation, where he weaves some amazing story telling, and it makes for a really enjoyable, nostalgic build. It makes you want to get under the hood and learn about computers all over again. The Z80 Membership Card features a Zilog Z80 microprocessor running at 4 MHz with 32k RAM and 32K EPROM, loaded with BASIC interpreter and monitor programs. A pair of 30-pin headers provide connections to power, I/O pins, data, address and control signals.

To accompany this board, he’s built a couple of companion “shield” boards. The Front Panel Card has a 16-key hex pad, 7-digit 7-segment LED display and Serial port. [Lee] has packed in a ton of features on the custom monitor ROM for the front panel card making it a versatile, two board, 8-bit system. Recently, he finished testing a third board in this series — a Serial/SD-Card/RAM shield which adds bank-switchable RAM and SD-card interface to provide “disk” storage. He’s managed to run a full CP/M-80 operating system on it using 64k of RAM. The two-board stack fits nicely in a regular Altoids tin. A fellow hacker who built the three-board sandwich found it too tall for the Altoids tin, and shared the design for a 3D printable enclosure.

[Lee] provides detailed documentation about the project on his blog with schematics, assembly instructions and code. He’s happy to answer questions from anyone who wants help building this computer. Do check out all of his other projects, a couple of which we’ve covered in the past. Check out Lee Hart’s Membership Card — a similar Altoids tin sized tribute to the 1802 CMOS chip and how he’s Anthropomorphizing Microprocessors.

Finally, we have to stress this once again — check out his Assembly Manuals [PDF, exhibit #1] — they are amazingly entertaining.

Thanks to [Matthew Kelley] who grabbed one of [Lee]’s kits and then tipped us off.

Z80 Based Raspberry Pi Look-alike

June 3, 2017 by Inderpreet Singh 53 Comments

Homebrew computers are the ‘in thing’ these days and the Zilog Z80 is the most popular choice for making one on your own. We have seen some pretty awesome builds but [Martin K]’s Z-berry is the smallest on record yet. As the name suggests, the retrocomputer conforms to the Raspberry Pi form factor which includes the GPIO header.

The Z-berry is designed with a Z80 CPU running at 10 MHz (20 MHz possible) and comes with 32 kB ROM
and 512 kB RAM. In addition to the serial interface, the computer boasts an I2C bus, an SPI bus, and a PS/2 keyboard connector to boot. [Martin K] has a video where the finished system is enclosed in a Raspberry Pi case and has an I2C OLED display attached and working.

[Martin K] has posted a lot of details on how to make your own Z-berry which includes the BOM, schematic and preliminary information. We reached out to him to find out more about the software which is stable and available on request along with PCBs and sample code. Additionally, this project promises to draw much less current than the Raspberry Pi and should prove useful for anyone looking to create a retro solution to a modern problem.

It is interesting to see projects that combine modern techniques with retro technologies. One of the best Z80 projects we have seen is the FAP80 and there are some awesome homebrew computer projects on Hackaday.io for you to take a look and get inspiration.
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Integrated Circuit Reverse Engineering, 1970s Style

June 2, 2017 by Jenny List 11 Comments

We are used to stories about reverse engineering integrated circuits, in these pages. Some fascinating exposés of classic chips have been produced by people such as the ever-hard-working [Ken Shirriff].

You might think that this practice would be something new, confined only to those interested in the workings of now-obsolete silicon. But the secrets of these chips were closely guarded commercial intelligence back in the day, and there was a small industry of experts whose living came from unlocking them.

Electron micrograph of a wire bond to the Z80 CTC die

Integrated Circuit Engineering Corporation were a Scottsdale, Arizona based company who specialised in semiconductor industry data. They have long since been swallowed up in a series of corporate takeovers, but we have a fascinating window into their activities because their archive is preserved by the Smithsonian Institution. They reverse engineered integrated circuits to produce reports containing detailed information about their mechanical properties as well as their operation, and just such a report is our subject today. Their 1979 examination of the Zilog Z80 CTC (PDF) starts with an examination of the package, in this case the more expensive ceramic variant, then looks in detail at the internal construction of the die itself, and its bonding wires. We are then taken in its typewritten pages through an extensive analysis of the circuitry on the die, with gate-level circuits to explain the operation of each part.

The detail contained in this report is extraordinary, it is clear that a huge amount of work went into its production and it would have been of huge value to certain of Zilog’s customers and competitors. At the time this would have been extremely commercially sensitive information, even if it now seems like a historical curiosity.

The Z80 CTC is a 4-channel counter/timer peripheral chip for the wildly succesful Z80 8-bit microprocessor, in a 28-pin dual-in-line package. We were surprised to find from a quick search that you can still buy this chip from some of the usual suppliers rather than the surplus houses, so it may even still be in production.

If IC reverse engineering takes your fancy, take a look at our archive of [Ken Shirriff] posts.

Thanks [fortytwo] for the tip.

Hackaday Links: May 7, 2017

May 7, 2017 by Brian Benchoff 19 Comments

The International Journal of PoC||GTFO is the hacker quarterly we all deserve. It’s Pastor Manul Laphroaig’s publication featuring crazy exploits and builds and neat woodcut illustrations. It’s going to be a freakin’ dead tree book published by No Starch Press. The word on the street is this is a literal bible. No, really. No Starch found a place that publishes (manufactures?) bibles, and they sent over the PDFs. There will probably be a Hackaday review of this book, but since all the content is freely available online, this review will literally only be judging a book by its cover.

Hoverboards are more innovative than a selfie stick. The snuggie is an innovative product. The iPhone came before greek yogurt. These are the findings of an online consumer research poll being held by CB Insights. As of this writing (and it might be updated by the time this is published), the bracket for the ‘Most Innovative Consumer Product Since The iPhone’ is down to two competitors — the Tesla Model S and the Raspberry Pi. That’s more opinion than anything, but check out the bracket. The Amazon Echo is more innovative than the ‘desktop 3D printer’, which as we all know was invented by MakerBot. The Dollar Shave Club — otherwise known as giving away the razor and selling subscriptions for the blades — is innovative. Taco Bell didn’t make it past the first round. What the hell is going on here?

This robot plays tiddlywinks. What’s tiddlywinks? It’s that game where you put your hand down on a table and stab a knife between your fingers. It’s a test of fine motor skills and courage, or in this case, programming. This robot also plays tiddlywinks.

This is a Kickstarter for an FPGA’d ZX Spectrum. With the blessing of Sky UK — the owner of the Amstrad brand — this team is cloning the ZX Spectrum, adding HDMI and SD card storage, creating a new enclosure, and calling this project the Spectrum Next. It’s fully compatible with the original and future proofs the Speccy for another few decades.

The Internet of Things comes to alcohol. This vodka comes with a wrap-around LED display that apparently has Bluetooth and is programmable with an iPhone or Android device. Why does this exist? Because it’ll sell. [Bryan Williams] bought one of these bottles and sent this in on the tip line. He’s currently waiting for the batteries to die so he can bust out the Dremel. If anyone else out there wants to check this out, it’s $11 at Sam’s Club.

Need a Z80 C compiler? Here you go.

Clickspring, the guy who has put far, far too much effort into building a clock is now working on the Antikythera Mechanism. His latest video demonstrates how the main plates of the Antikythera mechanism come together. There’s some interesting stuff here, but we’re really waiting for the main gears.

YouTube is well known for the technical astuteness of its community and the fair and level-headed comment section. This, for a short time, was one of the top trending videos on YouTube. It’s ‘free energy’ from two power strips. All you need to do is coil the leads of the power strips around each other. Free intermittent energy for life!

Z80 Fuzix Is Like Old Fashioned Unix

April 16, 2017 by Al Williams 98 Comments

Classic Z80 computers tend to run CP/M. If you’re a purist you’ll be happy with that because that’s certainly what most serious Z80 computers ran back in the day. However, for actual use, CP/M does feel dated these days. Linux is more comfortable but isn’t likely to run on a Z80. Or is it? Linux borrows from Unix and back in the 1980s [Doug Braun] wrote a Unix-like OS for the Z80 called UZI. There have been lots of forks of it over the years, and a project called FuzixOS aims to make a useful Z80 Unix-like OS.

Of course, 1980 Unix was a lot different from modern-day Linux, but it is still closer to a modern system than CP/M. Fuzix also adds several modern features like 30 character file names and up-to-date APIs. The kernel isn’t just for the Z80, by the way. It can target a variety of older processors including the 6502, the 6809, the 8086, and others. As you might expect, the system can fit in a pretty small system.

The video below shows [Scott Baker’s] RC2014 computer running Fuzix. You’ll see it looks a lot like a Linux system, although that analogy only goes so far.

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