retrocomputing

338 Articles

Blinkenlights-First Retrocomputer Design

January 11, 2025 by 10 Comments

[Boz] wants to build a retrocomputer, but where to start? You could start with the computery bits, like say the CPU or the bus architecture, but where’s the fun in that? Instead, [Boz] built a righteous blinkenlights array.

What’s cool about this display is that it’s ready to go out of the box. All of the LEDs are reverse-mount and assembled by the board maker. The 19″ 2U PCBs serve as the front plates, so [Boz] was careful not to use any through-hole parts, which also simplified the PCB assembly, of course. Each slice has its own microcontroller and a few shift registers to get the bits lit up, and that’s all there is to it. They take incoming data at 9600 baud and output blinkiness.

Right now it pulls out its bytes from his NAS. We’re not sure which bytes, and we think we see some counters in there. Anyway, it doesn’t matter because it’s so pretty. And maybe someday the prettiness will lure [Boz] into building a retrocomputer to go under it. But honestly, we’d just relax and watch the blinking lights.

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Retro Big Iron For You

January 8, 2025 by 27 Comments

Many of us used “big iron” back in the day. Computers like the IBM S/360 or 3090 are hard to find, transport, and operate, so you don’t see many retrocomputer enthusiasts with an S/370 in their garages. We’ve known for a while that the Hercules emulators would let you run virtual copies of these old mainframes, but every time we’ve looked at setting any up, it winds up being more work than we wanted to spend. Enter [Ernie] of [ErnieTech’s Little Mainframes]. He’s started a channel to show you how to “build” your own mainframe — emulated, of course.

One problem with the mainframe environment is that there are a bunch of operating system-like things like MVS, VM/CMS, and TSO. There were even custom systems like MUSIC/SP, which he shows in the video below.

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Atari 65XE In Laptop Form

January 5, 2025 by 2 Comments

For better or worse, Atari is no longer a household name in computing, but for a time in the 1980s, it was a huge mover in the industry. They not only produced PCs but also a huge number of video game consoles. Although they were a major contributor to the video game crash of the 1980s, they managed to limp along a few more years afterward and produce some interesting machines in the following years, even though they weren’t ultimately able to compete with Nintendo or Sega. One of those computers from that era was a PC-console hybrid of sorts called the Atari XE, and [Sideburn] was able to turn one into a laptop.

The retro laptop began life as an Arabic PAL version of the 65XE, the PC version of the ubiquitous 65-series computer. A large portion of the computer was reworked, including the removal of the power supply in favor of a rechargeable battery with a 6-hour life. Also among the list of scrapped components was the video and sound connectors as well as the RF modulator, which would have been common for displays at the time, but this laptop is getting a 1920×1080 LCD panel to replace all of that old hardware. A 1MB memory upgrade, new speakers and amp, a WiFi card, and an SD floppy card emulator round out the build.

The final part of the build is assembling it all into a custom 3D printed case, and the resulting laptop that [Sideburn] calls the XE Book is a faithful adaptation of this niche computer into what could have been a laptop we would have seen in the late 80s or early 90s similar to the Toshiba T3200SXC. It matches the original’s footprint and still uses all of the core components, so it’s not too difficult to imagine something like this having existed in the past.

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A Modern Battery For A Classic Laptop

January 2, 2025 by 12 Comments

Aside from their ability to operate fairly well in extreme temperatures, lead-acid batteries don’t have many benefits compared to more modern battery technology. They’re heavy, not particularly energy dense, have limited charge cycles, and often can’t be fully discharged without damage or greatly increased wear. With that in mind, one can imagine that a laptop that uses a battery like this would be not only extremely old but also limited by this technology. Of course, in the modern day we can do a lot to bring these retro machines up to modern standards like adding in some lithium batteries to this HP laptop.

Simply swapping the batteries in this computer won’t get the job done though, as lead-acid and lithium batteries need different circuitry in order to be safe while also getting the maximum amount of energy out. [CYUL] is using a cheap UPS module from AliExpress which comes with two 18650 cells to perform this conversion, although with a high likelihood of counterfeiting in this market, the 18650s were swapped out with two that were known to be from Samsung. The USB module also needs to be modified a bit to change the voltage output to match the needs of the HP-110Plus, and of course a modernized rebuild like this wouldn’t be complete without a USB-C port to function as the new power jack.

[CYUL] notes at the end of the build log that even without every hardware upgrade made to this computer (and ignoring its limited usefulness in the modern world) it has a limited shelf life as the BIOS won’t work past 2035. Hopefully with computers like this we’ll start seeing some firmware modifications as well that’ll let them work indefinitely into the future. For modern computers we’ll hope to avoid the similar 2038 problem by switching everything over to 64 bit systems and making other software updates as well.

The Bendix G-15 Runs 75,000 Lines Of Code

December 21, 2024 by 16 Comments

There’s a Blue Bendix in Texas, and thanks to [Usagi Electric] it’s the oldest operating computer in North America.  The Bendix G-15, a vacuum tube computer originally released in 1956, is now booting, and running code from paper tape. [David, aka Usagi] received the G-15 about a year ago from The System Source museum. The goal was to get the computer running so museum patrons could interact with a real tube computer. We’ve been following along since the project began.

[Usagi’s] latest G-15 video covers the last few problems on the road to running code. The biggest hurdle was the fact that the system wasn’t responding properly to the GO button on the typewriter. [Usagi] was able to isolate the issue down to a flip flop and then to a particular signal on an AND gate — the RC signal. The gate appeared to be bad, but swapping the entire circuit card multiple times had no effect. Something else had to be going on.

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Apple Newton Gets Rebuilt Battery Pack

December 13, 2024 by 14 Comments

We all carry touch screen computers around in our pockets these days, but before the smartphone revolution, there was the personal digital assistant (PDA). While it wasn’t a commercial success, one of the first devices in this category was the Apple Newton. Today they’re sought after by collectors, although most of the ones surviving to this day need a bit of rework to the battery pack. Luckily, as [Robert’s Retro] shows, it’s possible to rebuild the pack with modern cells.

By modern standards, the most surprising thing about these battery packs is both that they’re removable and that they’re a standard size, matching that of AA batteries. The Newton battery pack uses four cells, so replacing them with modern rechargeable AA batteries should be pretty straightforward, provided they can be accessed. This isn’t as easy, though. In true Apple fashion the case is glued shut, and prying it apart can damage it badly enough so it won’t fit back in the tablet after repair is complete. The current solution is to cut a hatch into the top instead and then slowly work on replacing the cells while being careful to preserve the electronics inside.

[Robert’s Retro] also demonstrates how to spot weld these new AA batteries together to prepare them for their new home in the Newton case. With the two rows fastened together with nickel strips they can be quickly attached to the existing electrical leads in the battery pack, and from there it’s just a matter of snapping the batteries into the case and sliding it back into the tablet. If you’re looking for something a bit more modern, though, we’d recommend this Apple tablet-laptop combo, but it’s not particularly easy on the wallet.

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Retro Computer Goes Back To The 1950s

December 6, 2024 by 24 Comments

When thinking of retrocomputing, many of us will imagine machines such as the Commodore 64 or Apple II. These computers were very popular and have plenty of parts and documentation available. Fewer will go back to the Intel 8008 or even 4004 era which were the first integrated circuit chips commercially available. But before even those transistor-based computers is a retrocomputing era rarely touched on: the era of programmable vacuum tube machines. [Mike] has gone back to the 1950s with this computer which uses vacuum tubes instead of transistors.

The computer has an eight-bit architecture and features most of the components of any modern transistor-based computer of similar computational ability. Memory, I/O, an arithmetic logic unit including a carry bit that allows it to do 16-bit arithmetic, are all implemented using 6N3P dual triode tubes that date to the 50s and 60s and would have been used in similar computers like the IBM 700. All of this drives a flight simulator program or a Fibonacci number generator, demonstrating its general purpose computing capabilities.

Of course, tubes were generally phased out in favor of transistors largely due to their power and space requirements; [Mike] needs a stepladder to maintain this computer as well as around ten minutes each time he starts it up to allow the tubes to warm up, with each module needing over three amps of current each. It’s a hugely impressive build and we’d recommend checking out the video linked below to get more details on its operation. If you’re looking for something a little more accessible to get into the world of vacuum tubes, this single-board tube computer fits the bill.

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