8080

15 Articles

An NEC V20 For Two Processors In One SBC

July 10, 2020 by 22 Comments

In the days when the best an impoverished student could hope to find in the way of computing was a cast-off 1980s PC clone, one upgrade was to fit an NEC V20 or V30 processor in place of the Intel 8088 or 8086. Whether it offered more than a marginal advantage is debatable, but it’s likely that one of the chip’s features would never have been used. These chips not only supported the 8086 instruction set, but also offered a compatibility mode with the older 8080 processor. It’s a feature that [Just4Fun] has taken advantage of, with V20-MBC, a single board computer that can run both CP/M-86 and CPM/80.

If this is starting to look a little familiar then it’s because we’ve featured a number of [Just4Fun]’s boards before. The Z80-MBC2 uses the same form factor, and like this V20 version, it has one of the larger ATMega chips taking place of the acres of 74 chips that would no doubt have performed all the glue logic tasks of the same machine had it been built in the early 1980s. There is a video of the board in action that we’ve placed below the break, showing CP/M in ’80, ’86, and even ’80 emulated in ’86 modes.

The only time a V20 has made it here before, it was in the much more conventional home of a home-made PC.

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Prolific Videos Show Altair 8800 Recreation

January 2, 2020 by 24 Comments

The January 1975 issue of Popular Electronics introduced the Altair 8800 and hit the newsstands in December of 1974, so it is only natural that around the New Year people start thinking about the old computer. [Shadowtron] did more than think about it. He ordered some replica PCBs and is building a new one. Even better, he’s posted an amazing number of videos (up to number 56 as I write this) detailing his progress. You can find part 1, below.

The boards are from Trailing Edge Technology. There’s a backplane board (about $100) as well as a few boards to fit it available for about $30 each — unpopulated, of course.

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Back To Where (For Most Of Us) It Started, The Intel 8080

June 15, 2019 by 41 Comments

The early history of microprocessors is a surprisingly complex one, with more than one claimant for the prize of being the first, and multiple competing families. That the first commercially available part was the Intel 4004 is a matter of record, but it’s fair to say that few of us will have ever encountered one. Even its 8-bit sibling the 8008 would not have featured heavily in a 1974 version of Hackaday, such was its exotic nature. If there’s a microprocessor that can be claimed to have started it all for us then, it’s the Intel 8080. It established the 8-bit microporcessor with an 8-bit bus and a 16-bit address space, it had an order of maginitude more performance than its predecessors, and crucially it would become affordable enough for experimenters. It provided the guts of the MITS Altair 8800 microcomputer, and thus kickstarted the progression of home computers which led to the devices you use every day.

The 8080 is in our sights today, thanks to [DeviceGuru], who was sent down memory lane by thoughts of the 6502-based KIM-1 from his master’s thesis project. This led to memories of the 8080 Abie computer that he built for himself in 1979, for which he provides us some details and hand-drawn schematics. By then the 8080’s need for several support chips made it somewhat outdated, but from his perspective the chip could be had from Radio Shack without too much outlay. His tale of hand-assembling 8080 code and sending it to a friend for blowing onto a PROM might be familiar to some readers of a certain age.

Though the 8080 ceased volume production a quarter century ago (surprisingly there are still places you can get a new one though) it hasn’t entirely disappeared from our community’s consciousness. [DeviceGuru] tells us about the 8080 Microprocessor kit from [Wichit Sirichote] in Thailand which is a single board computer in the 1970s vein, hex keypad and all.

As you might expect, the 8080 hasn’t appeared in many projects here due to its rarity. Those that have seem more likely to feature its Eastern Bloc clones, such as this Polish model or this Russian one. It’s worth the reminder that if you fancy exploring some 8080 code of your own that you don’t even need an 8080 to run it on some silicon. The hugely popular Zilog Z80 as found in retrocomputers such as the RC2014 is fully mostly 8080 code compatible, indeed some of us learned about microprocessors that way because 8080 books were discounted in 1983 and Z80 ones weren’t.

Header image: Konstantin Lanzet [CC BY-SA 3.0].

Polish Retro Silicon Brings This Computer To Life

January 28, 2019 by 12 Comments

It is an easy trap for us to write only about what we know when covering a topic, thus missing an entire facet of our subject matter. Take retrocomputing for example; we might write about American or Western European machines because we grew up with them, while completely ignoring the hardware being produced on the other side of the Iron Curtain.  Thus it’s fascinating to see [Marek Więcek]’s project, a single board retrocomputer employing a Polish clone of the Intel 8080.

With greater detail on a Polish-language forum (Google Translate), he tells a story of being given an MCY7880 CPU for his collection, only to wonder whether it could be made into a machine in its own right. As a clone of the 8080 this also required equivalents of the Intel bus controller and clock generator chips, which we are guessing must be the UCY74S405 and UCY7404 that he’s also sourced for the project.

The build is completed in true retro style with a maze of point-to-point wiring on the reverse of a protoboard, and he’s put a TinyBASIC interpreter port and 8251 UART on board as well as an 8255 triple parallel I/O port for some GPIO action. We love this computer, and appreciate the light it shines on an obscure corner of microprocessor history.

If Eastern European retrocomputing is your thing, here at Hackaday we’re lucky enough to number among our colleagues someone who’s something of an authority on the matter. [Voja Antonic] has entertained us with the tale of how he designed the Galaksija, Yugoslavia’s first home computer. Sadly though he did not use a Polish 8080 in his design.

Doing It With Fewer Bytes Than Bill Gates

March 24, 2017 by 29 Comments

The MITS Altair 8800 occupies a unique place in computing history as the first commercially succesful microcomputer for personal rather than business use. It is famous as the platform upon which the first Microsoft product ran, their first BASIC interpreter.

[Josh Bensadon] has an Altair 8800, and became intrigued by its bootloader. The simplest method of programming the machine is through binary using a set of switches on the front panel, and he remarks that there should be a warning in the manual: “fingers will get sore after repeated use of the small switches on the ALTAIR”.

In the Altair manual there are two listings, one 21 byte, and another in 20 bytes. Bill Gates is on record as saying that their first effort was 46 bytes long, but with more work he managed to create one in 17 bytes. Now [Josh] has beaten that, he’s created an Altair 8800 bootloader in only 14 bytes.

His write-up goes into great detail about how those bytes are shaved off, and provides us with a fascinating insight into the 8800’s architecture. Even if your 8-bit assembler is a little rusty, it’s a fascinating read.

We’ve featured Altair-inspired projects many times here at Hackaday, but rarely the real thing. This Altair PC case with the ability to emulate the original was rather a nice idea, as was this Altair front panel project. If you want the joy without the heartache though, there is an online emulator.

Retrocomputing On A Chip

December 3, 2015 by 10 Comments

New electrical components enable us to reconstruct old wiring more efficiently. Especially, the accessible and cheap FPGA kits which offer the possibility to put together wiring of many old computers as an “on-a-chip” solution.

When I managed to get a hold of an old bubble LED display and a pretty mechanical matrix keyboard, I decided to build a replica of an old single board computer. Logical options seemed to be to build either KIM-1 or Heathkit ET-3400. Replicas of KIM-1 already exist, even for Arduino, so my task would be reduced to connect the keyboard and display. But then I told myself that I would use the fact that my bubble display has 9 positions as an excuse to build the legendary Czechoslovak Single Board Computer PMI-80 which used the same display. My replica is an FPGA, or rather an FPGA emulator of this very computer.

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A Z80 Computer With Switches And Blinkenlights

December 1, 2014 by 50 Comments

While most people who build their own computer from chips want the finished product to do something useful, there’s something to be said about a huge bank of switches and a bunch of blinkenlights. They’re incredibly simple – most of the time, you don’t even need RAM – and have a great classic look about them.

[Jim] wanted to build one of these computers and wound up creating a minimal system with switches and blinkenlights. It’s based on the Z80 CPU, has only 256 bytes of RAM, and not much else. Apart from a few extra chips to output data and address lines to LEDs and a few more to read switches, there are only two major chips in this computer.

With the circuit complete, [Jim] laser cut a small enclosure big enough to house his stripboard PCB, the switches and LEDs, and a few buttons to write to an address, perform a soft reset, and cycle the clock. One of the most practical additions to this switch/blinkenlight setup is a hand crank. There’s no crystal inside this computer, and all clock cycles are done manually. Instead of pushing a button hundreds of times to calculate something. [Jim] added a small hand crank that cycles the clock once per revolution. Crazy, but strangely practical.

[Jim] made a demo video of his computer in action, demonstrating how it’s able to calculate the greatest common divisor of two numbers. You can check that video out below.

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