Building A Discrete Component 75 Baud Modem

August 21, 2026 by Zoe Skyforest 21 Comments

These days, modems are pretty fancy bits of kit, what with to keep up with the speeds of cable, VDSL, and fiber connections. At lower speeds, though, it’s entirely possible to build a modem out of simple discrete components. [sv3ora] did just that, building a simple modem for the CB2 Micro.

The project takes advantage of the fact that the V1.54 firmware for the CB2 Micro enabled 75 baud serial communication. Thus, it made sense for [sv3ora] to build a 75 baud modem to suit. As was the way in the days of dial-up internet, the modem modulates data into audio, demodulates audio back into data, allowing the CB2 Micro to send and receive data over telephone lines, ham radio links, or to store and retrieve data via mediums like cassette tape.

The device is built out of good old BC547 transistors. along with a smattering of diodes, resistors, and capacitors as supporting hardware. That’s all you need to turn slow serial into audio and back again. [sv3ora] does a great job of demoing the hardware, using it to store a program on tape and retrieve it again later.

We love old school modems around these parts. We’ve even explored ways to build your own dial-up ISP in the past!

Continue reading “Building A Discrete Component 75 Baud Modem” →

Homebrew 68K Machine Has A PCI Bus

August 20, 2026 by Zoe Skyforest 13 Comments

The Peripheral Component Interconnect (PCI) bus was first introduced all the way back in 1992. It quickly became the standard way to interface add-on cards on the PC platform, supplanting earlier buses like ISA and various other oddball standards. You wouldn’t expect to see a PCI bus on a Motorola-based machine, but [maniek86]’s homebrew rig offers just that.

This computer is a beautiful piece of homebrew engineering, constructed out of protoboard and loose wires rather than any fancy PCB. At the heart of the build lies a Motorola 68000 running at 10 MHz. It’s got 1 MB of SRAM, 4 KB of ROM, and a MC68681P acting as a UART, timer source, and I/O controller. Where things get special, though, is in the inclusion of a Xilinx Spartan II FPGA (XC2S100), which acts as a PCI bridge. It provides the machine with two 32-bit 5-volt PCI slots which are interrupt capable, albeit with no bus mastering. A XC95144XL CPLD also sits present to act as glue logic to help lace everything together.

[maniek86] does a great job of explaining exactly why the PCI bus was hard to implement, and how it was pulled off in the end. The guide also covers how the system was able to interface various cards, from a PCI serial expansion to a Cirrus VGA adapter. It’s all good stuff.

We’ve featured other work from [maniek86] before, too, like this brilliant 486-based single-board computer. Video after the break.

Continue reading “Homebrew 68K Machine Has A PCI Bus” →

Hackaday Europe 2026: The 1-Bit CPU That Ran Factories

August 19, 2026 by Zoe Skyforest 28 Comments

Powered machinery started the industrial revolution, and it was automation that kicked it up another notch in the 20th century. The ability for machines to make things by themselves spurred increased output and in turn boosted economic growth. The concept became widely popular for manufacturers to implement, as any change with serious economic benefit tends to do. Fast forward to today, and advanced robots and fancy machine vision systems running on powerful computers are the norm in modern factories which create the many wonderful products that we all purchase, use, and enjoy.

Once upon a time, though, things weren’t so sophisticated. [Nicola Cimmino] came to Hackaday Europe 2026 to tell us all about a remarkably simple 1-bit CPU that used to run factories.

Continue reading “Hackaday Europe 2026: The 1-Bit CPU That Ran Factories” →

Announcing The 2026 Hackaday Retrocomputing Challenge

August 18, 2026 by Elliot Williams 27 Comments

What is it about retrocomputing? For some people, it’s nostalgia. For others, it’s the appeal of simplicity. For still others, it’s the chance to save old machines from the graveyard. Whatever your motivation, there’s no denying that we’ve seen a metric ton of retrocomputer projects here at Hackaday. And we’d like to see more!

We’re happy to announce the 2026 Hackaday Retrocomputing Challenge!

Now’s the chance to put your retrocomputer project up for all to see. Open up a Hackaday.io project that features your retrocomputer project, and we’ll pick our three favorites for a $150 gift certificate courtesy of this contest’s sponsor, DigiKey. You have until Tuesday, October 27th. So get hacking!

Continue reading “Announcing The 2026 Hackaday Retrocomputing Challenge” →

One Man’s Perfect Retro-Style Monitor Takes All Inputs

August 17, 2026 by Tyler August 16 Comments

Perfection is an inherently subjective measure, in that one must choose the criteria against which to measure. A perfect circle is an absolutely rubbish octagon, for example. So when you see that [RetroBuiltGames] declares that he has built “the perfect multi-input display for retro gaming and vintage computing” — dubbed the “PixelVision AV1000 MKII”— keep in mind that he means the perfect display for his use case. That’s who he’s building it for, after all! The degree to which you find his product perfect is going to depend by-and-large how similar his use case is to yours. In that sense detailed explanations in the design/build video embedded below may be more valuable than the STEP files and PCBs in the GitHub link above– that way if your use case isn’t identical, you can perhaps learn something on the journey to build your own perfect monitor.

For [RetroBuiltGames] the aesthetic was obviously a big part of it– he’s inspired by the Amiga 1000’s monitor, and a tiny tilting Sony CRT TV. He was obviously looking for many inputs, as given by the title, and he has an unusually high interest in pixel density for a retro enthusiast. Hence a 9.7″ 2K iPad display forms the basis of the project. The multi-input aspect is provided by a retrotink clone whose PCB lives in a bulge on the back of the unit that could easily house an SBC if you wanted an all-in-one emulation station– it already has a couple of decent speakers mounted in the sides.

Another big piece of the puzzle we don’t see enough of in such projects is Design For Manufacturing– the manufacturing method of choice being FDM 3D printing. The whole assembly was designed in chunks that can be easily printed with the most visible surface flat on the bed – and if assembly proved difficult, than the parts were redesigned. His explanations aren’t a full DFM course by any means, but it’s good to see these things considered. If you need more detail on that front, we’ve featured plenty of such guides before.

We’re particularly taken by the conceit of creating his own packaging for the unit, and going to the effort of filming an unboxing video for a product he made himself. It’s just a bit of silly fun. We’ve seen boxes before, but generally speaking that sort of thing is saved for when a project becomes a product.

Continue reading “One Man’s Perfect Retro-Style Monitor Takes All Inputs” →

Toy Computer Restored

August 17, 2026 by Fenix Guthrie 10 Comments

In the 1960s, the home computer was barely a twinkle in anyone’s eye. This was the decade in which computers were used by a handful of companies and organizations and took up entire rooms. It was the decade that saw the birth of the first integrated-circuit computer, the Apollo Guidance Computer, and, rather strangely, one of the first home computers of sorts: the Digi-Comp 1.

In 1963, E.S.R. introduced this little programmable educational toy computer. It relies on simple mechanical logic gates, programmed by positioning tubes on sliders. Their original intention was to create actual computers, but one thing led to the next, and E.S.R. became the premier educational computer toy company of the 1960s. The Digi-comp is a rather simple device. A program is entered by soda-straw-like tubes placed on sliding rails. These tubes interact with spring-loaded levers which move in accordance with the “clock” switch. The result is a simple binary computer you can program.

Continue reading “Toy Computer Restored” →

Mauchly And Eckert’s Other Computers

August 14, 2026 by Al Williams 5 Comments

If you ask a random person who [John Mauchly] or [J. Presper Eckert] were, you’d probably get a blank stare. Ask a Hackaday reader, and you have a better shot. People who know will tell you that the two were behind the famous ENIAC, which may or may not have been the first computer, but was certainly influential in kicking off the modern computer era. They worked at Penn, and now [Holly Mengel] of Penn’s Kislak Center for Special Collections, Rare Books, and Manuscripts wants to introduce us to the other computers they worked on after ENIAC.

We will admit that we knew about EDVAC and UNIVAC. But we’ll also confess we didn’t know about BINAC or Skeduflo, a computer in a rather large suitcase. BINAC can claim to be the first digital computer that was commercialized, although you could argue that since it was fairly limited and, reportedly, never worked after it was delivered. Supposedly, the customer disassembled it, shipped it to a secure facility, and hired a freshly graduated engineer to rebuild it, which didn’t go very well.

We couldn’t find much about Skeduflo, other than that it was a 75-pound analog computer made for critical path method (CPM) analysis. You set up the problem with a patchboard and potentiometers, and the result came out on an analog plotter. Those details are from a PMI interview with [Morgan Walker] and [Jim Kelley].

It makes sense that these inventors didn’t just finish off ENIAC and retire to a tropical island. While UNIVAC had a good bit of success and EDVAC was very influential, the others are arguably fairly obscure. UNIVAC even has a Disney connection.