Version 1.8 of the 80386 ISA SBC in its assembled glory. (Credit: Alexandru Groza)

Building Your Own 80386DX ISA Single Board Microcomputer

Having grown up with 386-level systems during the early 90s like so many of us, [Alexandru Groza] experienced an intense longing to experience the nostalgia of these computer systems from an interesting angle: by building his own 80386DX-based single board computer. Courtesy of the 16-bit ISA form factor, the entire system fits into a 16-bit ISA backplane which then provides power and expansion slots for further functionality beyond what is integrated on the SBMC card.

Having started the project in 2019, it is now in the home stretch towards completion. Featuring an 80386DX and 80387DX FPU alongside 128 kB of cache and a grand total of 32 MB of RAM, an OPTi chipset was used to connect with the rest of the system alongside the standard 8042-class PS/2 keyboard and mouse controller. A large part of the fun of assembling such a system is that while the parts themselves are easy enough to obtain, finding datasheets is hard to impossible for some components.

Undeterred, some reverse-engineering of signaling on functional mainboards was sufficient to fill in the missing details. Helpfully, [Alexandru] provides the full schematics and BOM of the resulting board and takes us along with bootstrapping the system after obtaining the PCBs and components. After an initial facepalm moment due to an incorrectly inserted (and subsequently very dead) CPU and boot issues, ultimately [Alexandru] gave up on the v1.6 revision of the board

Fortunately the v1.8 revision with a logic analyzer led to a number of discoveries that has led to the system mostly working, minus what appears to be DMA-related issues. Even so, it is a remarkable achievement that demonstrates the complexity of these old systems.

Some Pleasing Experiments In 8-Bit Video Cards

These days, supply chain factors and high demand have made it incredibly difficult to lay one’s hands on a GPU. However, if you’re into older computers, you might find it hard to source old-school video cards too. Fear not, for [Dave’s Dev Lab] has been cooking up some experiments with a goal of eventually producing a new 8-bit ISA video card from scratch.

The long term goal is to recreate the original design of early IBM hardware, namely, the MDA and CGA video cards of decades past. The experiments center around the venerable Motorola 6845 which was widely used in computers in the 1980s. However, [Dave] intends to make them suitable for outputting to modern screens using typical VGA and DVI outputs, as well as those expected by modern TFT LCDs.

Thus far, [Dave] has achieved successful VGA output in a 40×35 text mode. With an 8×16 font, and the display running at 640×480 resolution at 60 Hz, everything hums along nicely. Similar experiments with a modern 480×272 LCD display have also worked well.

There’s a long way to go before [Dave’s] hardware is playing Commander Keen, but it’s great to see such effort being put into the platform. It could yet serve as a great upgrade for those wishing to use their vintage IBM metal without having to source a tired old CGA monitor.

We’ve seen similar work before too, with the Graphics Gremlin from [Tube Time] achieving a similar task. If you’ve been brewing up your own ISA hardware at home, do drop us a line.

Software Defined… CPU?

Everything is better when you can program it, right? We have software-defined radios, software-defined networks, and software-defined storage. Now a company called Ascenium wants to create a software-defined CPU. They’ve raised millions of dollars to bring the product to market.

The materials are a bit hazy, but it sounds as though the idea is to have CPU resources available and let the compiler manage and schedule those resources without using a full instruction set. A system called Aptos lets the compiler orchestrate those resources.

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Retro ISA Card Means Old, Slow Computers No Longer Need Old, Heavy Monitors

One thing about vintage computers is that they depend greatly on whether or not one can plug a compatible monitor into them. That’s what’s behind [Tube Time]’s Graphics Gremlin, a modern-design retro ISA video card that uses an FPGA to act just like a vintage MDA or CGA video card on the input end, but provides a VGA port for more modern display output options. (Actually, there is also an RGBI connector and a composite video out, but the VGA is probably the most broadly useful.)

Handy silkscreen labels make everything crystal clear. Click to enlarge.

Why bother making a new device to emulate an old ISA video card when actual vintage video cards are still plentiful? Because availability of the old cards isn’t the bottleneck. The trouble is that MDA or CGA monitors just aren’t as easy to come across as they once were, and irreplaceable vintage monitors that do still exist risk getting smashed during shipping. Luckily, VGA monitors (or at least converters that accept VGA input) are far more plentiful.

The board’s design files and assembly notes are all on the project’s GitHub repository along with plenty of thoughtful detail about both assembly and troubleshooting, and the Verilog code has its own document. The Graphics Gremlin is still under development, but you can also watch for the latest on [Tube Time]’s Twitter feed.

Thanks to [NoxiousPluK] for the tip!

Was Novell’s NE2000 Really That Bad?

If you used almost any form of networked PC in the late 1980s or the 1990s, the chances are that you will at some point have encountered the Novell NE2000 network card. This 16-bit ISA card became a de facto standard for 16-bit network cards, such that very few “NE2000” cards were the real thing. A host of clones filled the market, some of which followed the spec of the original rather loosely. It’s something [Michal Necasek] examines as he takes the reader through the history of the NE2000 and why it gained something of a bad reputation. An interesting read for ’90s PC veterans who battled with dodgy Windows 3.1 network drivers.

The Novell line of network cards were not a primary product of the network server OS company but an attempt to spur the uptake of networked computers in an age when few machines were supplied from the factory with a network card installed. They were largely an implementation of the reference design for the National Semiconductor DP3890 Ethernet interface chipset, and for simplicity of interfacing and drivers they used an I/O mapped interface rather than DMA. The problem with the NE2000 wasn’t the card itself which would work with any NE2000 driver, but the host of “NE2000 compatible” cards that appeared over the decade as that magic phrase became a key selling point at the bottom end of the market. Sure they might contain a DP3890 or its clones, but even minor differences in behaviour would cause them not to work with all drivers, and thus they gained a bad name. The piece reveals the original card as one that might have been slow and outdated towards the end of its reign as a standard card, but maybe one not deserving of the ire directed at it.

If ancient networking kit is your thing, we’ve got some far more obscure stuff to show you.

Retro Recreations Hack Chat With Tube Time

Join us on Wednesday, March 17 at noon Pacific for the Retro Recreations Hack Chat with Tube Time!

join-hack-chatNostalgia seems to be an inevitable consequence of progress. Advance any field far enough into the future, and eventually someone will look back with misty eyes and fond memories of the good old days and start the process of turning what would qualify as junk under normal conditions into highly desirable collectibles.

In some ways, those who have been bitten by the computer nostalgia bug are lucky, since the sheer number of artifacts produced during their period of interest is likely to be pretty high, making getting gear to lovingly restore relatively easy. But even products produced in their millions can eventually get difficult to find, especially once they get snapped up by eager collectors, leaving the rest to make do or do without.

Of course, if you’re as resourceful as Tube Time is, there’s another alternative: build your own retro recreations. He has embarked on some pretty intense builds to recapture a little of what early computer enthusiasts went through trying to build useful machines. He has built replicas of early PC sound cards, like an ISA-bus AdLib card, its MCA equivalent, and the “Snark Barker”— or is it the “Snood Bloober”? — which bears an uncanny resemblance to the classic Sound Blaster card from the 1980s.

Tube Time will join us for the Hack Chat this week to answer questions about all his retro recreations, including his newest work on a retro video card. Be sure to bring your questions on retro rebuilds, reverse engineering, and general computer nostalgia to the chat.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, March 17 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.
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ISASTM Runs Vintage Cards Over USB

The ISA bus is a relic of the distant past, and no longer supported by the PC mainstream. Outside of retro fanatics and likely some long-term industrial users, it’s all but forgotten. That hasn’t stopped [Manawyrm] from hacking away, however, and he’s developed a nifty adapter for the modern era.

Still in its early stages of development, the ISASTM is a ISA-over-USB adapter that allows a modern computer to work with older expansion cards. Running on an STM32H743, and using the microcontroller’s native USB1 interface, the ISASTM card is able to be slotted into a backplane in order to address multiple cards with one adapter. [Manawyrm] demonstrates the hardware by running Monkey Island 1 in the PCem emulator, with sound provided by an AdLib ISA soundcard.

There are some throughput issues, which [Manawyrm] aims to solve by switching to USB2 and making some tweaks and improvements to the code. Regardless, it’s an impressive tool that we imagine could have some use in keeping some legacy hardware alive, too. Incidentally, it’s been a long while since we’ve seen a solid ISA hack around these parts. Video after the break.

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