FPGA

387 Articles

M8SBC-486 Is An FPGA-Based “Kinda PC Compatible” 486 SBC

January 8, 2026 by 25 Comments

[Editor’s note: We got this one wrong! The computer uses an actual 486: the FPGA is running essentially as the chipset, interfacing the RAM and the ISA bus with the CPU. And since this went to press, [maniek-86] put out a nicer writeup of the project, which you should go check out, in addition to the GitHub link below.]

 

Given the technical specs of the FPGAs available to hobbyists these days, it really shouldn’t be a shock that you can implement a relatively-modern chipset on one, like one for a 486 system. In spite of knowing that in the technical sense, we were still caught off guard by [maniek-86]’s M8SBC project that does just that– the proas both CPU and BIOSducing a 486 FPGA chipset with a motherboard to boot.

Boot what? Linux 2.2.6, MS-DOS 6.22 or FreeDOS all work. It can run DOOM, of course, along with Wolfenstien 3D, Prince of Persia, and even the famous Second Reality demo– though that last without sound. [maniek-86]’s implementation is lacking direct memory access, so sound card support is right out. There are a few other bugs that are slowly being squished, too, according to the latest Reddit thread. Continue reading “M8SBC-486 Is An FPGA-Based “Kinda PC Compatible” 486 SBC” →

A photo of the PiStorm68K circuit board

PiStorm68K Offers Supercharged Retro Amiga Experience

January 6, 2026 by 10 Comments

[AmiCube] has announced their new PiStorm68K special edition MiniMig accelerator board. This board was developed to replace the 68000 CPU in a MiniMig — a recreation of the original Amiga chipset in an FPGA allowing a real genuine 68000 CPU to operate.

The PiStorm68K itself can host a real genuine 68000 CPU but it can also host various Raspberry Pi models which can do emulation of a 68000. So if you combine a PiStorm68K with a MiniMig you can, at your option, boot into an emulated environment with massively increased performance, or you can boot into an original environment, with its reliable and charming sluggishness.

In the introduction video below, [AmiCube] uses the SYSINFO utility software to compare the CPU speed when using emulation (1531 MIPS) versus the original (4.47 MIPS), where MIPS means Millions of Instructions Per Second. As you can see the 68000 emulated by the Raspberry Pi is way faster than the original. The Raspberry Pi also emulates a floating-point unit (FPU) which the original doesn’t include and a memory management unit (MMU) which isn’t used.

If you’re interested in old Amiga tech you might also like to read about Chip Swap Fixes A Dead Amiga 600 or The Many-Sprites Interpretation Of Amiga Mechanics.

Continue reading “PiStorm68K Offers Supercharged Retro Amiga Experience” →

PJON, Open Single-Wire Bus Protocol, Goes Verilog

December 13, 2025 by 12 Comments

Did OneWire of DS18B20 sensor fame ever fascinate you in its single-data-line simplicity? If so, then you’ll like PJON (Padded Jittering Operative Network) – a single-wire-compatible protocol for up to 255 devices. One disadvantage is that you need to check up on the bus pretty often, trading hardware complexity for software complexity. Now, this is no longer something for the gate wielders of us to worry about – [Giovanni] tells us that there’s a hardware implementation of PJDL (Padded Jittering Data Link), a PJON-based bus.

This implementation is written in Verilog, and allows you to offload a lot of your low-level PJDL tasks, essentially, giving you a PJDL peripheral for all your inter-processor communication needs. Oh, and as [Giovanni] says, this module has recently been taped out as part of the CROC chip project, an educational SoC project. What’s not to love?

PJON is a fun protocol, soon to be a decade old. We’ve previously covered [Giovanni] use PJON to establish a data link through a pair of LEDs, and it’s nice to see this nifty small-footprint protocol gain that much more of a foothold, now, in our hardware-level projects.

We thank [Giovanni Blu Mitolo] for sharing this with us!

[Gerry] holding up a DIP IC

Emulating A 74LS48 BCD-to-7-Segment Decoder/Driver With An Altera MAX 7000 “S” Series Complex Programmable Logic Device

November 11, 2025 by 25 Comments

Over on the [Behind The Code with Gerry] YouTube channel our hacker [Gerry] shows us how to emulate a 74LS48 BCD-to-7-segment decoder/driver using an Altera CPLD Logic Chip From 1998.

This is very much a das blinkenlights kind of project. The goal is to get a 7-segment display to count from 0 to 9, and that’s it. [Gerry] has a 74LS193 Up/Down Binary Counter, a 74LS42 BCD to Decimal Decoder, and some 74LS00 NAND gates, but he “doesn’t have” an 74LS48 to drive the 7-segment display so he emulates one with an old Altera CPLD model EPM7064SLC44 which dates back to the late nineties. A CPLD is a Complex Programmable Logic Device which is a kind of precursor to FPGA technology.

Continue reading “Emulating A 74LS48 BCD-to-7-Segment Decoder/Driver With An Altera MAX 7000 “S” Series Complex Programmable Logic Device” →

An FPGA-Based Mechanical Keyboard

October 1, 2025 by 16 Comments

You can buy all kinds of keyboards these days, from basic big-brand stuff to obscure mechanical delicacies from small-time builders. Or, you can go the maker route, and build your own. That’s precisely what [Lambert Sartory] did with their Clavier build.

This build goes a bit of a different route to many other DIY keyboards out there, in that [Lambert] was keen to build it around an FPGA instead of an off-the-shelf microcontroller. To that end, the entire USB HID stack was implemented in VHDL on a Lattice ECP5 chip. It was a heavy-duty way to go, but it makes the keyboard quite unique compared to those that just rely on existing HID libraries to do the job. This onboard hardware also allowed [Lambert] to include JTAG, SPI, I2C, and UART interfaces right on the keyboard, as well as a USB hub for good measure.

As for the mechanical design, it’s a full-size 105-key ISO keyboard with one bonus key for good measure. That’s the coffee key, which either locks the attached computer when you’re going for a break, or resets the FPGA with a long press just in case it’s necessary. It’s built with Cherry MX compatible switches, has N-key rollover capability, and a mighty 1000 Hz polling rate. If you can exceed that by hand, you’re some sort of superhuman.

The great thing about building your own keyboard is you can put in whatever features you desire. If you’re whipping up your own neat interface devices, don’t hesitate to let us know!

Retro X86 With 486Tang

September 14, 2025 by 4 Comments

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.

Continue reading “Retro X86 With 486Tang” →

Front and back view of the 13.7" monitor kit

Modos Is Open Hardware, Easy On The Eyes

September 8, 2025 by 26 Comments

Since e-ink first hit the market a couple decades back, there’s always murmurs of “that’d be great as a second monitor”— but very, very few monitors have ever been made. When the commecial world is delivering very few options, it leaves room for open source hardware projects, like the Modos Glider and Paper Monitor, projects now seeking funding on Crowd Supply.

As far as PC monitors go, the Modos isn’t going to win many awards on specs alone. The screen is only 13.3″ across, and its resolution maxes out at 1600 x 1200. The refresh rate would be totally unremarkable for a budget LCD, at 75 Hz. This Paper Monitor isn’t an LCD, budget or otherwise, and for e-ink, 75 Hz is a blazing fast refresh rate. Continue reading “Modos Is Open Hardware, Easy On The Eyes” →