Repairing Brittle Plastic Retro Computer Cases

Using UV resin as glue for new case clips. (Credit: More Fun Making It, YouTube)
Using UV resin as glue for new case clips. (Credit: More Fun Making It, YouTube)

As computers like the venerable breadbox Commodore 64 age, their plastic doesn’t just turn increasing shades of yellow and brown, the ABS plastic also tends to get brittle. This is a problem that seems to plague many plastic cases and enclosures, but fortunately there are some ways to halt or even reverse the heavy toll of time, with the [More Fun Making It] YouTube channel exploring a number of methods, including UV-curable resin, PETG 3D-printed clips and silicone molds.

Aside from large-scale damage, screw posts tend to snap off a lot, either during shipping or when merely trying to open the case. The same is true for the clips around the edge of the C64 case, which rarely survive that long. Gluing a case clip back on with epoxy or such somewhat works, but is messy and not that durable.

Instead UV resin is used, together with newly printed clips in translucent PETG. The remnants of the old clips are removed, followed by the application of the resin. The clips are actually a modified version of a VIC-20 case clip design by [Ken Mills]. With the UV resin as glue, curing is almost instant with a UV lamp unlike the tedious process with epoxy.

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M8SBC-486 Is An FPGA-Based “Kinda PC Compatible” 486 SBC

[Editor’s note: We got this one wrong! The computer uses an actual 486: the FPGA is running essentially as the chipset, interfacing the RAM and the ISA bus with the CPU. And since this went to press, [maniek-86] put out a nicer writeup of the project, which you should go check out, in addition to the GitHub link below.]

 

Given the technical specs of the FPGAs available to hobbyists these days, it really shouldn’t be a shock that you can implement a relatively-modern chipset on one, like one for a 486 system. In spite of knowing that in the technical sense, we were still caught off guard by [maniek-86]’s M8SBC project that does just that– the proas both CPU and BIOSducing a 486 FPGA chipset with a motherboard to boot.

Boot what? Linux 2.2.6, MS-DOS 6.22 or FreeDOS all work. It can run DOOM, of course, along with Wolfenstien 3D, Prince of Persia, and even the famous Second Reality demo– though that last without sound. [maniek-86]’s implementation is lacking direct memory access, so sound card support is right out. There are a few other bugs that are slowly being squished, too, according to the latest Reddit thread. Continue reading “M8SBC-486 Is An FPGA-Based “Kinda PC Compatible” 486 SBC”

Ken Shirriff working on the Commodore PET

This 8-Bit Commodore PET Was Hard To Fix

Over on [Ken Shirriff]’s blog is a tricky Commodore PET repair: tracking down 6 1/2 bad chips. WARNING: contains 8-bit assembly code.

The Trinity of 1977 which started the personal computer revolution were the Apple II, the Commodore PET, and the TRS-80. In this project it’s a failing Commodore PET which is being restored.

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A photo of the PiStorm68K circuit board

PiStorm68K Offers Supercharged Retro Amiga Experience

[AmiCube] has announced their new PiStorm68K special edition MiniMig accelerator board. This board was developed to replace the 68000 CPU in a MiniMig — a recreation of the original Amiga chipset in an FPGA allowing a real genuine 68000 CPU to operate.

The PiStorm68K itself can host a real genuine 68000 CPU but it can also host various Raspberry Pi models which can do emulation of a 68000. So if you combine a PiStorm68K with a MiniMig you can, at your option, boot into an emulated environment with massively increased performance, or you can boot into an original environment, with its reliable and charming sluggishness.

In the introduction video below, [AmiCube] uses the SYSINFO utility software to compare the CPU speed when using emulation (1531 MIPS) versus the original (4.47 MIPS), where MIPS means Millions of Instructions Per Second. As you can see the 68000 emulated by the Raspberry Pi is way faster than the original. The Raspberry Pi also emulates a floating-point unit (FPU) which the original doesn’t include and a memory management unit (MMU) which isn’t used.

If you’re interested in old Amiga tech you might also like to read about Chip Swap Fixes A Dead Amiga 600 or The Many-Sprites Interpretation Of Amiga Mechanics.

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Commodore Disk Drive Becomes General Purpose Computer

The Commodore 1541 was built to do one job—to save and load data from 5.25″ diskettes. [Commodore History] decided to see whether the drive could be put to other purposes, though. Namely, operating as a standalone computer in its own right!

It might sound silly, but there’s a very obvious inspiration behind this hack. It’s all because the Commodore 1541 disk drive contains a MOS 6502 CPU, along with some RAM, ROM, and other necessary supporting hardware. As you might remember, that’s the very same CPU that powers the Commodore 64 itself, along with a wide range of other 1980s machines. With a bit of work, that CPU can indeed be made to act like a general purpose computer instead of a single-purpose disk controller.

[Commodore History] compares the 1541 to the Commodore VIC-20, noting that the disk drive has a very similar configuration, but less than half the RAM. The video then explains how the drive can be reconfigured to run like the even-simpler MOS Technology KIM-1 — a very primitive but well-known 8-bit machine. What’s wild is that this can be achieved with no hardware modifications. It’s not just a thought exercise, either. We get a full “Hello World!” example running in both BASIC and machine code to demonstrate that it really works.

Code is on GitHub for the curious. We’ve featured hacks with the chunky Commodore 1541 before, too.

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Print Pixel Art To A Floppy Disk

Here at Hackaday we love floppy disks. While they are by no means a practical or useful means of storing data in the age of solid state storage, there is something special about the little floppy disc of magnetic film inside that iconic plastic case. That’s why we were so excited to see the tool [dbalsom] developed for printing pixel art in a floppy’s track timing diagrams!

Floppy timing diagrams are usually used to analyze the quality of an individual disk. It represents flux transitions within a single floppy tack as a 2D graph. But it’s also perfectly possible to “paint” images on a floppy this way. Granted, you can’t see these images without printing out a timing diagram, but if you’re painting images onto a floppy, that’s probably the point.

This is where pbm2track comes in handy! It takes bitmap images and encodes them onto floppy emulators, or actual floppies. The results are quite excellent, with near-perfect recreation in floppy graphical views. The results on real floppies are also recognizable as the original image. The concept is similar to a previous tool [dbalsom] created, PNG2disk

If you, too, love the nearly forgotten physical likeness of the save button, make sure to check out this modern Linux on a floppy hack next!

Thanks [gloriouscow] for the tip!

FPGA Dev Kit Unofficially Brings MSX Standard Back

In the 1980s there were an incredible number of personal computers of all shapes, sizes, and operating system types, and there was very little interoperability. Unlike today’s Windows-Mac duopoly, this era was much more of a free-for-all but that didn’t mean companies like Microsoft weren’t trying to clean up all of this mess. In 1983 they introduced the MSX standard for computers, hoping to coalesce users around a single design. Eventually it became very successful in Japan and saw some use in a few other places but is now relegated to the dustbin of history, but a new FPGA kit unofficially supports this standard.

The kit is called the OneChip Book and, unlike most FPGA kits, includes essentially everything needed to get it up and running including screen, keyboard, and I/O all in a pre-built laptop case. At its core it’s just that: and FPGA kit. But its original intent was to recreate this old 80s computer standard with modern hardware. The only problem is they never asked for permission, and their plans were quickly quashed. The development kit is still available, though, and [electricadventures] goes through the steps to get this computer set up to emulate this unofficially-supported retro spec. He’s also able to get original MSX cartridges running on it when everything is said and done.

Although MSX is relatively unknown in North America and Western Europe, it remains a fairly popular platform for retro computing enthusiasts in much of the rest of the world. We’ve seen a few similar projects related to this computer standard like this MSX-inspired cyberdeck design, but also others that bring new hardware to this old platform.

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