ATX Adapter For The IBM PCJr Now Available

We’ve mentioned previously the challenges that come with maintaining vintage computers which in some cases are pushing 40 years old. Components, even high quality ones, eventually fail and need to be replaced. Now if it’s a fairly popular vintage machine, replacement parts usually aren’t too hard to come by. But what if you’re dealing with a machine that’s not just vintage, but was also such a commercial flop that parts are scarce?

Such is the life for anyone who owns one of the 500,000 IBM PCJrs that Big Blue managed to get out of the door during the year or so the product was on the market. As [AkBKukU] found, a replacement AC adapter for the odd-ball computer was going to cost more than what he paid for the thing, so he set to work on creating an adapter so he could use a modern ATX PSU on the machine. After a couple of months of ironing out the kinks, the design is finally ready for consumption.

In the end, the PCB design itself is quite simple. It’s really just a matter of switching around some pins from the standard ATX plug to the edge connector on the PCJr. There’s also a connector for powering a floppy drive, as well as headers for a fan and power switch.

[AkBKukU] has come up with two ways to use the adapter. You can either go with a standard ATX PSU, in which case it will need to sit outside the machine due to its size, or use a PicoPSU which allows you to keep the whole thing internal. If you don’t mind spending the cash, the PicoPSU method is a much cleaner installation that still provides plenty of power. Depending on which route you take, there are different 3D printed plates to adapt the computer’s rear panel to fit the new hardware.

All the files to build your own version are in the GitHub repository, and [AkBKukU] is doing some low volume runs of both kits and assembled adapter. If this project looks familiar, it’s because we reported on it back when it was still a hand-scratched PCB that didn’t always work as expected.

[Thanks to Gregg for the tip.]

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An Incredible ATX Amiga 4000 Motherboard

No matter how far modern computer hardware advances, there’s still a fairly large group of people who yearn for the early days of desktop computing. There’s something undeniably appealing about these early systems, and while even the most hardcore vintage computer aficionado probably wouldn’t be using one as their daily computer anymore, it’s nice to be able to revisit them occasionally. Of course the downside of working with computers that may well be older than their operators is that they are often fragile, and replacement parts are not necessarily easy to come by.

But thanks to projects like this impressive ATX Amiga 4000 motherboard shown off by [hese] on the Amibay forums, getting first hand experience with classic computing doesn’t necessarily mean relying on vintage hardware. By making an Amiga that’s compatible with standard ATX computer cases and power supplies, it becomes a bit more practical to relive the Commodore glory days. Right now it’s mainly a personal project, but if there’s sufficient interest it sounds as if that might change.

This board could be considered a modern reincarnation of the Amiga 4000T, which was an official tower version of the standard Amiga 4000 released by Commodore in 1994. It features a 68030 CPU, with 16 MB Fast RAM and 2 MB Chip RAM. For expansion there are four full-length Zorro III slots and three ISA slots, as well as IDE ports for a floppy and hard drive.

The board really looks the part of a professionally manufactured computer motherboard from the late 1990s, which speaks not only to the attention to detail [hese] put into its design, but the manufacturing capabilities that are now available to the individual. With passionate people like this involved, it’s hardly surprising that the vintage computer scene is so vibrant.

Of course, this isn’t the first newly built “vintage” computer we’ve seen here at Hackaday. From bare-minimum 8085 computers to the comparative luxury of the 6502-powered Cactus, it seems like what’s old is new again.

[Thanks to Laurens for the tip.]

IBM PCjr Revived by an ATX Power Supply and Many False Starts

The IBM PCjr was a computer only the marketing geniuses of a multi-billion dollar corporation could love. On the face of it, it seemed like a great idea – a machine for the home market, meant to complement the “big boy” IBM PC in the office and compete against the likes of Apple and Commodore. What it ended up as was a universally hated, only partially PC-compatible machine which sold a mere half-million units before being mercifully killed off.

That doesn’t mean retrocomputing fans don’t still snap up the remaining machines, of course. [AkBKukU] scored a PCjr from a thrift store, but without the original external brick power supply. An eBay replacement for the 18-VAC supply would have cost more than the computer, so [AkBKukU] adapted a standard ATX power supply to run the PCjr. It looked as if it would be an easy job, since the external brick plugs into a power supply card inside the case which slots into the motherboard with a card-edge connector. Just etch up a PCB, solder on an ATX Molex connector, and plug it in, right? Well, not quite. The comedy of errors that ensued, from the backward PCB to the mysteriously conductive flux, nearly landed this one in the “Fail of the Week” bin. But [AkBKukU] soldiered on, and his hand-scratched adapter eventually prevailed; the video below tells the whole sordid tale, which thankfully ended with the sound of the machine booting from the 5-1/4″-floppy drive.

In the end, we’ve got to applaud [AkBKukU] for taking on the care and feeding of a machine so unloved as to be mentioned only a handful of times even on these pages. One of those articles marks the 25th anniversary of the PCjr, and lays out some of the reasons for its rapid disappearance from the market.

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A Smarter PSU Converter Leaves the Magic Smoke Inside

Over the years, computers have become faster, but at the same time, more power hungry as well. Way back around the 386 era, most PCs were using the AT standard for power supplies. Since then, the world moved on to the now ubiquitous ATX standard. Hobbyists working on older machines will typically use these readily available supplies with basic adapters to run old machines, but [Samuel] built a better one.

Most AT to ATX adapters are basic passive units, routing the various power lines where they need to go and tying the right pin high to switch the ATX supply on. However, using these with older machines can be fraught with danger. Modern supplies are designed to deliver huge currents, over 20 A in some cases, to run modern hardware. Conversely, a motherboard from the early 90s might only need 2 or 3A. In the case of a short circuit, caused by damage or a failed component, the modern supply will deliver huge current, often damaging the board, due to the overcurrent limit being set so high.

[Samuel]’s solution is to lean on modern electronics to build an ATX to AT adapter with programmable current protection. This allows the current limit to be set far lower in order to protect delicate boards. The board can be set up in both a “fast blow” and a “slow blow” mode to suit various working conditions, and [Samuel] reports that with alternative cabling, it can also be used to power up other old hardware such as Macintosh or Amiga boards. The board is even packed with extra useful features like circuitry to generate the sometimes-needed -5V rail. It’s all programmed through DIP switches and even has an OLED display for feedback.

It’s an adapter that could save some rare old hardware that’s simply irreplaceable, and for that reason alone, we think it’s a highly important build. We’ve talked about appropriate fusing and current limiting before, too – namely, with LED strips. 

 

Case Mod Takes “All In One” Printer to the Next Level

You’ve seen printers with scanners in them, printers with copiers in them, even ones with the ancient technology known as “facsimile” built-in. But have you ever seen a printer with a full gaming computer built into it? No? Well, you still haven’t, technically. There’s no printer to be had anymore inside this re-purposed HP Photosmart 6520 case, but it’s probably the closest we’re going to get.

[Jacob Lee] wrote in to share this awesome build with us, which sees the motherboard, graphics card, ATX power supply, and hard drives all fit seamlessly into the shell of a disused “All-in-one” style printer. Incredibly, he even managed to integrate an LCD into the top; which hinges open when in use and gives a look down into the madness that makes this build tick.

To say there’s a lot of hardware packed into this thing is an understatement. Which is all the more impressive when you consider that he] didn’t take the easy way out for any of it. He could have used a mini-ITX motherboard, or a slim PSU. He could have even dropped the graphics card for integrated. No, [Jacob] is clearly a subscriber to the “Go big or go home” ethos.

As if putting all this gear inside of a normal looking printer case wasn’t impressive enough, he even went as far as adding female ports for Ethernet, HDMI, and USB on the rear of the device to give it a stock look. He mentions there’s some room for improvement with the USB ports, but the power switch and IEC port really look like they could have been original components.

In the age of the Raspberry Pi and other diminutive computers, we don’t see too many proper desktop computer projects anymore. Fewer still that are so well executed and creative. We don’t know how many other people might be trying to stick a computer in a printer case, but if they’re out there, the bar has just been set pretty high.

Not Your Typical ATX Bench PSU

We know what you’re thinking — yet another scrap PC power supply turned into a bench PSU. But look a little closer and you’ll see a nicely designed linear bench supply that just fits inside a gutted ATX case.

A lot of the items on [Medzik]’s BOM for this build are straight from the scrap bin. The aforementioned ATX supply case is one, as is the power transformer donated by a friend. Modules such as the 30V/2A regulator, the digital volt/ammeter, and a thermostat module to control the fan at higher power settings were all sourced via the usual suspects. The PSU boasts two outputs — an adjustable 0-22 volt supply, and a fixed 12-volt output. An unusual design feature is a secondary input which uses the 22-VAC supply from a Weller soldering station to give the PSU a little more oomph. This boosts the maximum output to 30 volts; one wonders why [Medzik] didn’t just source a bigger transformer, but you work with what you have sometimes. There are some nice touches, too, like custom-printed vinyl overlays for the case.

It’s a good-looking and compact unit with a decent suite of features, and you could do a lot worse when building your next bench supply. If it’s not your cup of tea though, just take your pick — tiny and yellow, built to last, or ensconced in Ultrasuede.

The Improved Luggable PC

There are exactly two types of personal computers available today. If you need a lot of horsepower, a powerful GPU, or a full-power CPU, you’re going to end up with a desktop. If you need something portable, you’re getting a laptop with a wimpy CPU and an underpowered GPU. Historically, there has been a third type of PC, the luggable. The luggable is a desktop PC crammed into a case that makes it slightly more portable than a desktop and a monitor.  You cannot buy a luggable PC case right now. They simply do not exist as a commercial product you can shove your own hardware into. This is a form factor an entire industry forgot.

Now there’s a DIY luggable PC. This project from [Roger] packs a standard ATX motherboard, a full-size GPU, a full-size power supply, and everything else that makes a desktop PC powerful into a case that can be stored in an overhead bin.

[Roger] has been working on this project for a while, and it was featured on Hackaday back when it looked like a RepRap Mendel. There have been some significant improvements over the earlier iterations of this project, including a very, very cool hinge mechanism that allows the display to fold in when the computer isn’t being used. It’s a mechanical wonder that prevents scratches. Neat. The rest of the case is constructed out of 2020 aluminum extrusion, and about a one kilogram spool of filament.

Since this is a portable case, there are a few compromises. There are no 5.25″ bays, no 3.5″ bays, and few 2.5″ bays. M.2 SSDs and USB-powered CD drives exist, so this isn’t a big deal.

This is a truly fantastic case in a form factor you can’t buy anywhere else. If you have a spare monitor and a bit of extrusion sitting around, this is one to build yourself.