This week Jonathan and Aaron chat with Piers Finlayson about One ROM! Why does the retro-computing world need a solution for replacement ROMs? How difficult was it to squeeze a MCU and layout into the original ROM footprint? And what’s next for the project? Listen to find out!
Continue reading “FLOSS Weekly Episode 850: One ROM To Rule Them All”
Ok, we’ll admit it. If you asked us what the first transistorized computer was, we would have guessed it was the TC from the University of Manchester. After all, Dr. Wilkes and company were at the forefront and had built Baby and EDSAC, which, of course, didn’t use transistors. To be clear, we would have been guessing, but what we didn’t know at all was that the TC, with its magnetic drums and transistors in 1955, had a second life as a commercial product from Metropolitan-Vickers, called the Metrovick 950. [Nina Kalinina] has a simulator inspired by the old machine.
The code is in Python, and you can find several programs to run on the faux machine, including the venerable lunar lander. If you haven’t heard of the Metrovick, don’t feel bad. Oral histories say that only six or seven were ever built, and they were used internally within the company.
For all its friendly countenance and award-winning industrial design, there’s one thing the venerable Macintosh Plus can’t do: fit into a 1U rack space. OK, if we’re being honest with ourselves, there are a lot of things a Mac from 1986 can’t do, but the rack space is what [identity4] was focused on when they built the 2025 Rackintosh Plus.
For those of you already sharpening your pitchforks, worry not: [identity4]’s beloved vintage Mac was not disassembled for this project. This rack mount has instead become the home for a spare logic board they had acquired Why? They wanted to use a classic Mac in their studio, and for any more equipment to fit the space, it needed to go into the existing racks. It’s more practical than the motivation we see for a lot of hacks; it’s almost surprising it hasn’t happened before. (We’ve seen Mac Minis in racks, but not the classic hardware.)
Aside from the genuine Apple logic board, the thin rack also contains a BlueSCSI hard drive emulator, a Floppy Emu for SD-card floppy emulator, an RGB-to-HDMI converter to allow System 7 to shine on modern monitors, and of course a Mean Well power supply to keep everything running.The Floppy Emu required a little light surgery to move the screen so it would fit inside the low-profile rack. [identity4] also broke out the keyboard and mouse connectors to the front of the rack, but all other connectors stayed on the logic board at the rear.
Sound is handled by a single 8-ohm speaker that lives inside the rack mount, because even if the Rackintosh can now fit into a 1U space, it still can’t do stereo sound…or anything else a Macintosh Plus with 4 MB of RAM couldn’t do. Still, it’s a lovely hack. and the vintage-style advertisement was an excellent touch.
Now they just need the right monochrome display.
If you are interested in retrocomputers, you might be like us and old enough to remember the old systems and still have some of the books. But what if you aren’t? No one is born knowing how to copy a file with PIP, for example, so [Kraileth] has the answer: A Gentle Introduction to CP/M.
Of course, by modern standards, CP/M isn’t very hard. You had disks and they had a single level of files in them. No subdirectories. We did eventually get user areas, and the post covers that near the end. It was a common mod to treat user 0 as a global user, but by default, no.
If you’ve never used a PDP-11 before it’s probably because you simply weren’t around in the 70s and 80s. Although they started as expensive machines only in research labs and industry, they eventually became much more accessible. They’re a bit of a landmark in computing history, too, being largely responsible for the development of things like UNIX and the C programming language. [ryomuk] is using an FPGA in combination with an original DEC J-11 to bring us a new take on this machine. (Google Translate from Japanese)
The FPGA used in this build is a Tang Nano 20k, notable for its relatively low cost. The FPGA emulates the memory system and UART of a PDP-11 system down to the instruction set, while the original, unmodified DEC chip is left to its own devices. After some initial testing [ryomuk] built a PC11 paper tape emulator to ensure the system was working which runs a version of BASIC from the era. The next thing up was to emulate some disk drives and co-processors so that the machine can run the first version of UNIX.
[ryomuk] also developed a PCB for the DEC microprocessor and the FPGA to sit on together, and it includes all of the jumpers and wiring needed to allow the computer to run UNIX, as well as handling other miscellaneous tasks like power. It’s an interesting build that gets to the heart of the early days of computer science. PDP-11 computers did eventually get smaller and more accessible, and if you want to build a modern version this build fits a complete system into an ATX case.
Thanks to [RetepV] for the tip!
There are few computing collapses more spectacular than the downfall of Commodore, but its rise as a home computer powerhouse in the early 80s was equally impressive. Driven initially by the VIC-20, this was the first home computer model to sell over a million units thanks to its low cost and accessibility for people outside of niche markets and hobbyist communities.
The VIC-20 would quickly be eclipsed by the much more famous Commodore 64, but for those still using these older machines there are a few tweaks to give it some extra functionality it was never originally designed for like this build which gives it an ISA bus.
To begin adapting the VIC-20 to the ISA standard, [Lee] built a fixed interrupt line handled with a simple transistor circuit. From there he started mapping memory and timing signals. The first attempt to find a portion of memory to use failed as it wasn’t as unused as he had thought, but eventually he settled on using the I/O area instead although still had to solve some problems with quirky ISA timing. There’s also a programmable logic chip which was needed to generate three additional signals for proper communication.
After solving some other issues around interrupts [Lee] was finally able to get the ISA bus working, specifically so he could add a 3Com networking card and get his VIC-20 on his LAN. Although the ISA bus has since gone out of fashion on modern computers, if you still have a computer with one (or build one onto your VIC-20), it is a surprisingly versatile expansion port.
Thanks to [Stephen] for the tip!
Although not the first video game ever produced, Pong was the first to achieve commercial success and has had a tremendous influence on our culture as a whole. In Pong’s time, its popularity ushered in the arcade era that would last for more than two decades. Today, it retains a similar popularity partially for approachability: gameplay is relatively simple, has hardwired logic, and provides insights about the state of computer science at the time. For these reasons, [Nick Bild] has decided to recreate this arcade classic, but not in a traditional way. He’s trained a neural network to become the game instead.
