Repairing An HDMI Adapter Doesn’t Go So Well

May 16, 2022 by Al Williams 27 Comments

[Adrian] has a lot of retrocomputers, so he uses an RGB to HDMI converter to drive modern monitors. In particular, he has a box that uses a programmable logic chip to read various RGB signals and ships them to a Raspberry Pi Zero to drive the HDMI output. Sounds great until, of course, something goes wrong.

A converter that had worked stopped working due to a bad board with the programmable logic chip on it. Unlike the retrocomputers, this board has little tiny surface mount components. A little analysis suggested that some of the chip pins were not accepting inputs.

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Striping A Disk Drive The 1970 Way

May 16, 2022 by Al Williams 38 Comments

These days, mass storage for computers is pretty simple. It either uses a rotating disk or else it is solid state. There are a few holdouts using tape, too, but compared to how much there used to be, tape is all but dead. But it wasn’t that long ago that there were many kinds of mass storage. Tapes, disks, drums, punched cards, paper tape, and even stranger things. Perhaps none were quite so strange though as the IBM 2321 Data Cell drive — something IBM internally called MARS.

What is a data cell you might ask? A data cell was a mass storage device from IBM in 1964 that could store about 400 megabytes using magnetic strips that looked something like about a foot of photographic film. The strips resided inside a drum that could rotate. When you needed a record, the drum would rotate the strip you needed to the working part and an automated process would remove the strip in question, wrap it around a read/write head and then put it back when it was done.

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Computer Thing Might Be Garbage

May 15, 2022 by Al Williams 9 Comments

[Tech Time Traveller] has a lot of voices in his head this week, and most of them are worried about his wife’s reaction to him buying other people’s garbage. We don’t blame him, though. He bought it from an estate sale and it was billed as a TV typewriter. The device looked completely homebrewed from somewhere around the late 1970s to the early 1980s. It contains a mess of components obviously hand-built in a combination of neat construction and messy wiring.

[Tech] videos most of his tests and exploration to get the thing working and tested. Given its age and construction, it worked surprisingly well, although it did take a little work to get it back to complete function. In fact, he bought the device three years ago and is finally getting around to finishing the project and putting together the video.

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Retrotechtacular: The IBM System/360 Remembered

May 13, 2022 by Al Williams 52 Comments

Before IBM was synonymous with personal computers, they were synonymous with large computers. If you didn’t live it, it was hard to realize just how ubiquitous IBM computers were in most industries. And the flagship of the mainframe world was the IBM System/360. For a whole generation that grew up in the late 1960s and early 1970s, a 360 was probably what you thought of when someone said computer. [Computer History Archive Project] has a loving recollection of the machine with a lot of beautiful footage from places like NASA and IBM itself. You can see the video below.

Not only was the 360 physically imposing, but it had lots of lights, switches, and dials that appealed to the nerdiest of us. The machines were usually loud, too, with a Selectric terminal, card punches and readers, noisy 9-track tape drives, and a line printer or two.

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Will MiSTer Fool You Into Learning FPGAs?

May 9, 2022 by Elliot Williams 45 Comments

What’s the killer app for FPGAs? For some people, the allure is the ultra-high data throughput for parallelizable tasks, which can enable some pretty gnarly projects. But what if you’re just starting out? How about 1980s style video games?

The MiSTer FPGA project created a bit of FPGA hardware that makes it easy to build essentially any old school video game or computer platform. That’s a massive clean slate. Of course, you can simply download someone else’s Atari ST or Commodore 64 setup and load it up, but if you want to learn FPGAs while recreating old-school video game machines, you’re going to want to get your hands dirty.

[Mister Retro Wolf] started up a video series last winter (trailer embedded below) where he’s embarked on a project to recreate a classic video game machine from the ground up using the MiSTer FPGA platform. In particular, he’s going to recreate the Namco Tank Battalion arcade game, from the schematics, in Verilog.

This is literally building a 6502-based video game machine from scratch (in gateware), so if you’re interested in retrocomputing or FPGAs, you’ll have something to learn here. He’s gotten through the CPU, screen, tilemap graphics, and memory so far, but it’s not done yet. To follow along, get yourself some hardware and you can probably catch up.

We’ve covered the MiSTer FPGA project before, of course, because we think it’s cool. And if a video game arcade machine is going to be your gateway drug into the seedy world of programmable gates, then so be it.

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Altaid 8800 Puts A Front Panel In Your Pocket

May 8, 2022 by Tom Nardi 11 Comments

It’s safe to say that the Altair 8800 is one of the most iconic, and important, computers ever created. The kit-built machine is widely regarded as the first commercially successful personal computer, and as such, intact specimens are bona fide historical artifacts when and if they ever come up on the second-hand market. Accordingly there’s a cottage industry out there dedicated to making affordable replicas, which more often than not, leverage modern hardware to emulate the original hardware.

But that’s not what the Altaid 8800 is. For one thing, it looks nothing like the original Altair. More to the point however, it’s not using modern components to emulate an Intel 8080 computer…it actually is an Intel 8080 computer — complete with fully functional front panel for manually entering in programs. It just happens to be small enough to fit into an Altoids tin, hence the name.

Creator [Lee Hart] didn’t just stop at building a miniature 8080 machine, either. He’s also gone through the trouble of producing a sixteen page faux-vintage magazine to describe the project and its operation. Normally we’d call such a document a “manual”, but somehow in this case that seems to downplay the incredible effort and attention to detail that went into it.

Schematics and firmware are available should you wish to build your own version of the Altaid 8800, but we think the prices for the bare PCBs and complete kits that [Lee] is offering are more than fair for what you get. In fact, if you’ve always wanted to play around with front panel programming and the associated blinkenlights, this might be one of the most affordable options available. Though to be clear, you can also hook the Altaid up to your computer with a USB-to-serial cable if you’re not up to punching in programs on those tiny buttons.

You might think this is one of the most creative and unique retrocomputing projects we’ve ever seen, and you’d be right…if it wasn’t for [Lee]’s own Z80 Membership Card. In some ways the precursor to the Altaid 8800, this diminutive triumph also fits in an Altoids tin and features its own era appropriate magazine-style documentation. We’re detecting something of a theme with these projects…but we certainly aren’t complaining.

Reviving A 1974 Sinclair Scientific Calculator

May 8, 2022 by Jenny List 6 Comments

When a treasure of retrotechnology fails to work, the natural next step is to have a go at repairing it. [Adam Wilson] found himself in this position when he acquired a 1974 Sinclair Cambridge Scientific calculator, and his progress with the device makes for an interesting read.

First up is something of value to all old Sinclair enthusiasts, he’s found a solution to the original battery connectors being prone to failure. A couple of parts stocked by RS can be used as replacements, which should save quite a lot of Sinclairs with crusty connectors.

Saving the connectors should have fixed the calculator, but only served to reveal that it had an electronic fault. Some detective work traced this to the power supply, which is a small switching circuit. The 1974 chip and associated coil had both failed, which rather drew the project to a halt. A second repair-or-spares Cambridge Scientific was sourced, and by good luck it happened to have a working PCB. So [Adam] got a working calculator, and we hope he’ll succumb to the temptation to shoehorn in a PSU from 2022 to get the other one working.

Anyone curious about this slightly unusual calculator should take a look at our teardown of one.