An FPGA Version Of The AT&T UNIX PC For MiSTer

We all have our childhood heroes, which in the case of [Hrvoje Cavrak] was the 1985 AT&T UNIX PC. This 18 kg behemoth of a workstation computer boasted a 10 MHz Motorola 68010 CPU, up to 4 MB of RAM and dozens of megabytes of storage in addition to endless expansion options, making it a powerhouse of a personal computer for the discerning professional. Now, many decades later [Hrvoje] has an FPGA-based version to tinker with.

This project targets the MiSTer project, meaning that this softcore with SystemVerilog, Verilog and VHDL components should synthesize and run on any MiSTer-compatible FPGA system, such as the DE10 Nano. For that board the SDRAM add-on board is required due to the DE10 Nano Cyclone V SoC’s FPGA side only having access to a fraction of the 4 MB required by the softcore.

Obviously the boot ROM and disk images for AT&T UNIX are still under copyright, so although you can download both you should be wary of provoking the current copyright holder. With that in place, however, you now have got access to a very complete UNIX PC experience, as can be seen in the demonstration video.

Some aspects of the code were written and validated by LLM coding chatbots, so this is still a ‘works on my MiSTer board’ project. In lieu of getting access to the real hardware – meanwhile priced at unobtanium levels – this seems like a fair enough trade-off if old workstations like these are your thing.

The UNIX PC obviously didn’t make it into mainstream computer as we covered previously, with the IBM PC with MS-DOS, CP/M and Apple’s systems quickly cornering the home market along with Commodore, Atari, etc. This possibly makes these AT&T UNIX PCs even more rare than 1990s SGI and Sun systems.

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Putting A MiSTer Marquee On A Better Display

Some MiSTer users put a small secondary “marquee” display on the FPGA board that can show information about the system such as the currently loaded core and what game it happens to be running. Generally these take the form of a small monochrome OLED display, likely the one most of us have sitting in a parts bin somewhere.

But [Erico Mendonca] wanted a something with a bit more style, so he’s come up with a firmware for the ESP32-C3 that connects to MiSTer’s existing secondary display protocol but works with slightly more visually impressive panels such as the round GC9A01 that so many hackers have been playing with as of late. If the whole circular display thing isn’t your…thing, you can even run the firmware on the Cheap Yellow Display for a turn-key rectangular experience.

Because [Erico] didn’t want to fiddle with anything on the MiSTer side of the equation, his firmware has to do the heavy lifting when it comes to the art that shows on the display. So there’s a web-based editor that lets you put together your own artwork to show on the marquee based on what command the MiSTer has actually sent out. Flashing the firmware on the ESP32 can be done through the browser as well, as is becoming increasingly common these days, making it relatively easy to get this project up and running.

With this project it’s also possible to control multiple client displays over WiFi from one system, just in case you wanted to show off what console you were booting up in multiple places.

We’re fans of the round display here at Hackaday, so it’s been great to see more folks putting them to use as of late.

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Retro X86 With 486Tang

Tang FPGA boards are affordable, and [nand2mario] has been trying to get an x86 core running on one for a while. Looks like it finally worked out, as there is an early version of the ao486 design on a Tang FPGA board using a Gowin device. That core’s available on the MiSTer platform, which emulates games using an Altera Cyclone device.

Of course, porting something substantial between FPGA architectures is not trivial. In addition, [nand2mario] made some changes. The original core uses DDR3 memory, but for the Tang and the 486, SDRAM makes more sense. The only problem is that the Tang’s SDRAM is 16 bits wide, which would imply you need two cycles per 32-bit access. To mitigate this, the memory system runs at twice the main clock frequency. Of course, that’s kind of double data rate, but not in the same way as DDR memory.

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C64 on desk with NFC TeensyROM and game token

TeensyROM NFC Game Loading On The C64

When retro computing nostalgia meets modern wireless wizardry, you get a near-magical tap-to-load experience. It’ll turn your Commodore 64 into a console-like system, complete with physical game cards. Inspired by TapTo for MiSTer, this latest hack brings NFC magic to real hardware using the TeensyROM. It’s been out there for a while, but it might not have caught your attention as of yet. Developed by [Sensorium] and showcased by YouTuber [StatMat], this project is a tactile, techie love letter to the past.

At the heart of it is the TeensyROM cartridge, which – thanks to some clever firmware modding – now supports reading NFC tags. These are writable NTag215 cards storing the path to game files on the Teensy’s SD card. Tap a tag to the NFC reader, and the TeensyROM boots your game. No need to fumble with LOAD “*”,8,1. That’s not only cool, it’s convenient – especially for retro demo setups.

What truly sets this apart is the reintroduction of physical tokens. Each game lives on its own custom-designed card, styled after PC Engine HuCards or printed with holographic vinyl. It’s a tangible, collectible gimmick that echoes the golden days of floppies and cartridges – but with 2020s tech underneath. Watch it here.

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MiSTER Multisystem 2 on a wooden table

MiSTer For Mortals: Meet The Multisystem 2

If you’ve ever squinted at a DE10-Nano wondering where the fun part begins, you’re not alone. This review of the Mr. MultiSystem 2 by [Lee] lifts the veil on a surprisingly noob-friendly FPGA console that finally gets the MiSTer experience out of the tinker cave and into the living room. Developed by Heber, the same UK wizards behind the original MultiSystem, this follow-up console dares to blend flexibility with simplicity. No stack required.

It comes in two varieties, to be precise: with, or without analog ports. The analog edition features a 10-layer PCB with both HDMI and native RGB out, Meanwell PSU support, internal USB headers, and even space for an OLED or NFC reader. The latter can be used to “load” physical cards cartridge-style, which is just ridiculously charming. Even the 3D-printed enclosure is open-source and customisable – drill it, print it, or just colour it neon green. And for once, you don’t need to be a soldering wizard to use the thing. The FPGA is integrated in the mainboard. No RAM modules, no USB hub spaghetti. Just add some ROMs (legally, of course), and you’re off.

Despite its plug-and-play aspirations, there are some quirks – for example, the usual display inconsistencies and that eternal jungle of controller mappings. But hey, if that’s the price for versatility, it’s one you’d gladly pay. And if you ever get stuck, the MiSTer crowd will eat your question and spit out 12 solutions. It remains 100% compatible with the MiSTer software, but allows some additional future features, should developers wish to support them.

Want to learn more? This could be your entrance to the MiSTer scene without having to first earn a master’s in embedded systems. Will this become an alternative to the Taki Udon announced Playstation inspired all-in-one FPGA console? Check the video here and let us know in the comments. Continue reading “MiSTer For Mortals: Meet The Multisystem 2” →

PicoROM, A DIP-32 8-Bit ROM Emulator

As we all know, when developing software for any platform or simply hacking a bit of code to probe how something works, the ability to deploy code rapidly is a huge help. [Martin Donlon], aka [wickerwaka], is well known in retro gaming and arcade hardware reverse engineering circles and had the usual issues figuring out how an arcade CPU board worked while developing a MiSTer core. Some interesting ASICs needed quite a bit of poking, and changing the contents of socketed ERPOMs is a labour-intensive process. The solution was PicoROM, a nicely designed ROM emulator in a handy DIP-32 form factor.

As the title suggests, PicoROM is based on the Raspberry Pi RP2040. It emulates an 8-bit ROM up to 2MBits in size with speeds up to 100ns. Since it uses the RP2040, USB connectivity is simple, enabling rapid uploading of new images to one (or more) PicoROMs in mere seconds. A vertically orientated USB-C connector allows multiple PicoROMs to be cabled to the host without interfering with neighbouring hardware. The firmware running on core 1 passes data from the internal 264K SRAM, using the PIO block as a bus interface to the target. A neat firmware feature is the addition of a mechanism to use a ROM region as a bidirectional control channel, which the software running on the target can use to communicate back to the host computer. This allows remote triggering of actions and the reporting of responses. Responses which may not be physically observable externally. [Martin] is using this feature extensively to help probe the functionality of some special function chips on the target boards, which is still a slow process but helped massively by reducing that critical software iteration time. The PCB was designed with KiCAD. The project files for which can be found here.

This isn’t the first time we’ve seen the RP2040 used for ROM emulation; here’s a pile of wires that does the same job. It just isn’t as pretty. Of course, if you really must use EPROMs, then you could give this sweet programmer a look over.

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Exploring TapTo NFC Integration On The MiSTer

[Ken] from the YouTube channel What’s Ken Making is back with another MiSTer video detailing the TapTo project and its integration into MiSTer. MiSTer, as some may recall, is a set of FPGA images and a supporting ecosystem for the Terasic DE10-Nano FPGA board, which hosts the very capable Altera Cyclone V FPGA.

The TeensyROM C64 cart supports TapTo

The concept behind TapTo is to use NFC cards, stickers, and other such objects to launch games and particular key sequences. This allows an NFC card to be programmed with the required FPGA core and game image. The TapTo service runs on the MiSTer, waiting for NFC events and launching the appropriate actions when it reads a card. [Ken] demonstrates many such usage scenarios, from launching games quickly and easily with a physical ‘game card’ to adding arcade credits and even activating cheat codes.

As [Ken] points out, this opens some exciting possibilities concerning physical interactivity and would be a real bonus for people less able-bodied to access these gaming systems. It was fun to see how the Nintendo Amiibo figures and some neat integration projects like the dummy floppy disk drive could be used.

TapTo is a software project primarily for the MiSTer system, but ports are underway for Windows, the MiSTex, and there’s a working Commodore 64 game loader using the TeensyROM, which supports TapTo. For more information, check out the TapTo project GitHub page.

We’ve covered the MiSTer a few times before, but boy, do we have a lot of NFC hacks. Here’s an NFC ring and a DIY NFC tag, just for starters.

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