Urban Explorers Reveal A Treasure Trove Of Soviet Computing Power

November 30, 2020 by Jenny List 45 Comments

It’s probably a dream most of us share, to stumble upon a dusty hall full of fascinating abandoned tech frozen in time as though its operators walked away one day and simply never returned. It’s something documented by some Russian urban explorers who found an unremarkable office building with one of its floors frozen sometime around the transition from Soviet Union to Russian Federation. In it they found their abandoned tech, in the form of a cross-section of Soviet-era computers from the 1970s onwards.

As you might expect, in a manner it mirrors the development of civilian computing on the capitalist side of the Iron Curtain over a similar period, starting with minicomputers the size of several large refrigerators and ending with desktop microcomputers. The minis seem to all be Soviet clones of contemporary DEC machines. with some parts of them even looking vaguely familiar. The oldest is a Saratov-2, a PDP/8 clone which we’re told is rare enough for no examples to have been believed to have survived until this discovery. We then see a succession of PDP/11 clones each of which becomes ever smaller with advancements in semiconductor integration, starting with the fridge-sized units and eventually ending up with desktop versions that resemble 1980s PCs.

While mass-market Western desktop machines followed the path of adopting newer architectures such as the Z80 or the 8086 the Soviets instead took their minicomputer technology to that level. It would be interesting to speculate how these machines might further have developed over the 1990s had history been different. Meanwhile we all have a tangible legacy of Soviet PDP/11 microcomputers in the form of Tetris, which was first written on an Elektronika 60.

We know that among our readers there is likely to be a few who encountered similar machines in their heyday, and we hope they’ll share their recollections in the comments. Meanwhile we hope that somehow this collection can be preserved one day. If your thirst for dusty mincomputers knows no bounds, read about the collectors who bought an IBM machine on eBay and got more than they bargained for.

Via Hacker News.

DVK-1 desktop computer, «Переславская неделя» / В. С. Спиридонов CC-BY-SA 3.0.

TMD-2: A Bigger, Better, More Collaborative Turing Machine

November 28, 2020 by Dan Maloney 3 Comments

One of the things we love best about the articles we publish on Hackaday is the dynamic that can develop between the hacker and the readers. At its best, the comment section of an article can be a model of collaborative effort, with readers’ ideas and suggestions making their way into version 2.0 of a build.

This collegial dynamic is very much on display with TMD-2, [Michael Gardi]’s latest iteration of his Turing machine demonstrator. We covered the original TMD-1 back in late summer, the idea of which was to serve as a physical embodiment of the Turing machine concept. Briefly, the TMD-1 represented the key “tape and head” concepts of the Turing machine with a console of servo-controlled flip tiles, the state of which was controlled by a three-state, three-symbol finite state machine.

TMD-1 was capable of simple programs that really demonstrated the principles of Turing machines, and it really seemed to catch on with readers. Based on the comments of one reader, [Newspaperman5], [Mike] started thinking bigger and better for TMD-2. He expanded the finite state machine to six states and six symbols, which meant coming up with something more scalable than the Hall-effect sensors and magnetic tiles of TMD-1.

TMD-2 has a camera for computer vision of the state machine tiles

[Mike] opted for optical character recognition using a Raspberry Pi cam along with Open CV and the Tesseract OCR engine. The original servo-driven tape didn’t scale well either, so that was replaced by a virtual tape displayed on a 7″ LCD display. The best part of the original, the tile-based FSM, was expanded but kept that tactile programming experience.

Hats off to [Mike] for tackling a project with so many technologies that were previously new to him, and for pulling off another great build. And kudos to [Newspaperman5] for the great suggestions that spurred him on.

Finally! The ROM You Wished Your Sinclair Spectrum Had!

November 27, 2020 by Jenny List 10 Comments

If there is one thing that Sir Clive SInclair was famous for, it was producing electronic devices that somehow managed to squeeze near-impossible performance out of relatively meagre components. This gave us some impressive products, but it’s fair to say that sometimes this philosophy pushed the envelope a little too far. Thus even some of the most fondly remembered Sinclair products concealed significant flaws, and this extended to both their hardware and their software.

The SInclair ZX spectrum’s ROM for example had more than its fair share of bugs, and its BASIC programming experience with single keypress was unique but also slow to run. It’s something [Jonathan Cauldwell] has addressed with his Arcade Game Designer ROM, a complete and ready to run replacement for the original Spectrum ROM that contains a scripting language, a compiler, editors for in-game assets, and a game engine upon which to run your games. It’s the ROM you wanted back in 1983, when you were struggling to fit a bit of Z80 code in a Sinclair Basic REM statement.

If you’re a Spectrum enthusiast and think this sounds a little familiar then you are of course correct. It builds upon his past work with his Arcade Game Designer, with the distribution by ROM allowing the developer to use the full 48k available on all but a very few early 16k machines. You’ll need your own EPROM on which to burn it, but we suspect that if you’re the kind of person who has a Spectrum and has writing these games in mind, you already have access to the relevant equipment.

If you’re new to all this Spectrum stuff and where its ROM came from, then maybe it’s time for a trip down memory lane.

A CPU-Less Computer With A Single NOR-Gate ALU

November 23, 2020 by Dan Maloney 13 Comments

We see a lot of discrete-logic computer builds these days, and we love them all. But after a while, they kind of all blend in with each other. So what’s the discrete logic aficionado to do if they want to stand out from the pack? Perhaps this CPU-less computer with a single NOR-gate instead of an arithmetic-logic unit is enough of a hacker flex? We certainly think so.

We must admit that when we first saw [Dennis Kuschel]’s “MyNor” we thought all the logic would be emulated by discrete NOR gates, which of course can be wired up in various combinations to produce every other logic gate. And while that would be really cool, [Dennis] chose another path. Sitting in the middle of the very nicely designed PCB is a small outcropping, a pair of discrete transistors and a single resistor. These form the NOR gate that is used, along with MyNor’s microcode, to perform all the operations normally done by the ALU.

While making the MyNor very slow, this has the advantage of not needing 74-series chips that are no longer manufactured, like the 74LS181 ALU. It may be slow, but as seen in the video below, with the help of a couple of add-on cards of similar architecture, it still manages to play Minesweeper and Tetris and acts as a decent calculator.

We really like the look of this build, and we congratulate [Dennis] on pulling it off. He has open-sourced everything, so feel free to build your own. Or, check out some of the other CPU-less computers we’ve featured: there’s the Gigatron, the Dis-Integrated 6502, or the jumper-wire jungle of this 8-bit CPU-less machine.

Continue reading “A CPU-Less Computer With A Single NOR-Gate ALU” →

Booting A PC From Vinyl For A Warmer, Richer OS

November 23, 2020 by Dan Maloney 60 Comments

If you’ve scrolled through the list of boot options offered on any PC’s BIOS, it reads like a history of storage technology. Up top we have the options to boot from disk, often a solid-state drive, then USB disk, optical drive, removable media, and down the bottom there’s usually an option to boot from the network. Practically no BIOS, however, has an option to boot a PC from a vinyl record — at least until now.

Clearly a project from the “Because why not?” school of hacking, [Jozef Bogin] came up with the twist to the normal booting process for an IBM-PC. As in the IBM-PC — a model 5150, with the putty-colored case, dual 5-1/4″ floppies, and one of those amazing monochrome displays with the green slow-decay phosphors. To pull off the trick, [Jozef] leverages the rarely used and little known cassette tape interface that PCs had back in the early days. This required building a new bootloader and burning it to ROM to make the PC listen to audio signals with its 8255 programmable peripheral interface chip.

Once the PC had the right bootloader, a 64k FreeDOS bootable disk image was recorded on vinyl. [Jozef] provides infuriatingly little detail about the process other than to mention that the audio was sent directly to the vinyl lathe; we’d have loved to learn more about that. Nonetheless, the resulting 10″ record, played back at 45 RPM with some equalization tweaks to adapt for the RIAA equalization curve of the preamp, boots the PC into FreeDOS just fine, probably in no more time than it would have taken to boot from floppy.

It’s may not be the first time we’ve seen software on vinyl, but it’s still a pretty cool hack. Want to try it yourself but lack a record-cutting lathe? Maybe laser-cutting your boot disc will work.

Continue reading “Booting A PC From Vinyl For A Warmer, Richer OS” →

Intel’s Forgotten 1970s Dual Core Processor

November 22, 2020 by Jenny List 56 Comments

Can you remember when you received your first computer or device containing a CPU with more than one main processing core on the die? We’re guessing for many of you it was probably some time around 2005, and it’s likely that processor would have been in the Intel Core Duo family of chips. With a dual-core ESP32 now costing relative pennies it may be difficult to grasp in 2020, but there was a time when a multi-core processor was a very big deal indeed.

What if we were to tell you that there was another Intel dual-core processor back in the 1970s, and that some of you may even have owned one without ever realizing it? It’s a tale related to us by [Chris Evans], about how a team of reverse engineering enthusiasts came together to unlock the secrets of the Intel 8271.

If you’ve never heard of the 8271 you can be forgiven, for far from being part of the chip giant’s processor line it was instead a high-performance floppy disk controller that appeared in relatively few machines. An unexpected use of it came in the Acorn BBC Micro which is where [Chris] first encountered it. There’s very little documentation of its internal features, so an impressive combination of decapping and research was needed by the team before they could understand its secrets.

As you will no doubt have guessed, what they found is no general purpose application processor but a mask-programmed dual-core microcontroller optimized for data throughput and containing substantial programmable logic arrays (PLAs). It’s a relatively large chip for its day, and with 22,000 transistors it dwarfs the relatively svelte 6502 that does the BBC Micro’s heavy lifting. Some very hard work at decoding the RMO and PLAs arrives at the conclusion that the main core has some similarity to their 8048 architecture, and the dual-core design is revealed as a solution to the problem of calculating cyclic redundancy checks on the fly at disk transfer speed. There is even another chip using the same silicon in the contemporary Intel range, the 8273 synchronous data link controller simply has a different ROM. All in all the article provides a fascinating insight into this very unusual corner of 1970s microcomputer technology.

As long-time readers will know, we have an interest in chip reverse engineering.

C64 Runs On STM32F429 Discovery

November 18, 2020 by Chris Lott 23 Comments

There have been various reincarnations of the Commodore C64 over the years, and [Dave Van Wagner] has created one that can run on an STM32F429ZI Discovery development board. These dev boards have been around quite a few years and feature a 2.4 inch color TFT LCD in addition to the typical I/O circuitry, and are a pretty good value — [Dave] says they currently sell for under $30 through distribution.

The project began earlier this year when [Dave] set out to write a command line program in C# that emulated C64 Basic. He had written a 6502 emulator many years earlier, but had not tested it. [Dave] went on a programming binge in March and got it up and running over a very long weekend. He subsequently decided to add support for VIC-20, TED, and PET as well.

Even though [Dave] says C# is a beautiful language, he subsequently ported the program into C (an ugly language?) in order to run on the Discovery board, swapping the command line terminal interface for real LCD video and a USB keyboard. There’s also an Arduino version (terminal interface only). It runs about 15% slower than a real C64, and there are some limitations still like no SID. But overall, this is a great project and a low-cost way to emulate a C64 in an embedded format. If you want to explore further, here is the Mbed project for the STM32F429, and you can find the Arduino and C# versions on his GitHub page. You may remember [Dave] from the C128 video hack we wrote about last year.