Retrocomputing

1675 Articles

Recreating The Amiga 1200 PCB From Pictures

August 28, 2018 by 35 Comments

In the past we’ve talked about one of the major downsides of working with vintage computer hardware, which of course is the fact you’re working with vintage computer hardware. The reality is that these machines were never designed to be up and running 20, 30, or even 40-odd years after they were manufactured. Components degrade and fail, and eventually you’re going to need to either find some way to keep your favorite classic computer up and running or relegate it to becoming a display piece on the shelf.

If you’re like [John Hertell], you take the former option. Knowing that many an Amiga 1200 has gone to that great retrocomputing museum in the sky due to corroded PCBs, he decided to recreate the design from scans of an unpopulated board. While he was at it, he tacked on a few modern fixes and enhancements, earning his new project the moniker: “Re-Amiga 1200”.

To create this updated PCB, [John] took high quality scans of an original board and loaded them up into Sprint Layout, which allows you to freely draw your PCB design over the top of an existing image. While he admits the software isn’t ideal for new designs, the fact that he could literally trace the scan of the original board made it the ideal choice for this particular task.

After the base board was recreated in digital form, the next step was to improve on it. Parts which are now EOL and hard to come by got deleted in place of modern alternatives, power traces were made thicker, extra fan connectors were added, and of course he couldn’t miss the opportunity to add some additional status blinkenlights. [John] has released his Gerber files as well as a complete BOM if you want to make your own Re-Amiga, and says he’ll also be selling PCBs if you don’t want to go through the trouble of getting them fabricated.

It seems as if Amiga fans never say never, as this isn’t the first time we’ve seen one brought back from the brink of extinction by way of a modernized motherboard. Whatever it takes to keep the vintage computing dream alive.

[Thanks to Anders for the tip.]

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Using Modern Nintendo Controllers On The C64

August 23, 2018 by 12 Comments

There are plenty of people out there who still enjoy playing games on vintage computers like the Commodore 64. But while they likely return to these classic games themselves out of a sense of nostalgia, the feeling doesn’t always extend to the hardware itself. For example, one can enjoy playing Impossible Mission without having to use a contemporary C64 joystick.

Thanks to an open source project developed by [Robert Grasböck], C64 owners who want to take advantage of the improvements made to gaming controllers in the nearly 40 years since the system’s release now have another option. Called Nunchuk64, it allows you to use various Nintendo controllers which make use of the Wii “Nunchuk” interface on original C64 hardware. This includes the controllers from the recent “Classic Edition” NES and SNES systems, which offer a decidedly retro feel with all the benefits of modern technology and construction techniques.

Both the hardware and software for Nunchuck64 are open source, and everything you need to build your own version is in the project’s repository. [Robert] even has assembly instructions, complete with images, which walk you through building your own copy of the hardware and flashing the firmware onto it. This is a nice touch that we very rarely see even in open source projects. The board is populated with a ATmega328P microcontroller and a handful of passive components, making assembly fairly straightforward assuming you are comfortable with SMD work.

Bringing more modern controllers to classic systems seems to be gaining popularity recently, within the last few months we’ve seen Xbox 360 controllers on the Nintendo 64, and newly manufactured pads for the Atari 5200.

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IBM PCjr Revived By An ATX Power Supply And Many False Starts

August 10, 2018 by 26 Comments

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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Python Resurrects Dot Matrix Printing

August 9, 2018 by 54 Comments

These days a printer — especially one at home — is likely to spray ink out of nozzles. It is getting harder to find home laser printers, and earlier printer technologies such as dot matrix are almost gone from people’s homes even if you’ll still see a few printing multipart forms in some offices.

[Thomas Winningham] bought an old Commodore dot matrix printer in a fast food parking lot for $20. How hard could it be to get it working? How hard, indeed. Check out the video below to see the whole adventure. The principle behind the printer is simple enough. The head has one or two rows of pins each controlled by a solenoid. The head moves across the paper and your job — should you decide to accept it — is to make the pins push out at the right spot. An ink ribbon like a typewriter uses — oh yeah, more vanishing tech — leaves ink on the paper where it gets punched by the pin.

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Thumbs Up For This Custom Atari 5200 Controller

August 8, 2018 by 16 Comments

It may be nearly 40 years old, but the Atari 5200 still inspires legions of fans to relive the 8-bit glory days of their youth. There was much to love about the game console, but the joystick-and-keypad controllers were not among its many charms. The joystick didn’t auto-center, the buttons were mushy, and the ergonomics were nonexistent.

Retro-aficionados need not suffer in silence, though, thanks to this replacement controller for the Atari 5200. [Scott Baker] didn’t want to settle for one of the commercial replacements or, horrors, an adapter for the old PC-style joystick, so he rolled his own. Working from the original Atari schematics, [Scott] devised a plan for using a readily available thumbstick controller as the basis for his build. The essential problem was how to adapt the 10k pots on the new joystick to work in an environment expecting 500k pots, which he solved using an analog to digital and back to analog approach. The ADCs on an ATtiny85 convert each joystick pot’s voltage to a digital value between 0 and 255, which is sent to a 100K digital potentiometer. A little fiddling with RC constants brings it back in line with what the console expects. The thumbstick and buttons live on a custom PCB – kudos to [Scott] for designing an ambidextrous board. The video below shows the design and the finished product in action.

[Scott] is on a bit of a 5200 kick these days; he just finished up a Raspberry Pi multi-cartridge for the venerable console. His controller should make retro-gameplay on the console a little easier on the hands.

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Ancient Teletype Revived In Labor Of Retrocomputing Love

August 2, 2018 by 19 Comments

Readers with not too many years under their belts may recall a time when the classic background sound effect for radio and television news programs included a staccato mechanical beat, presumably made by the bank of teletype machines somewhere in the studio, clattering out breaking stories onto rolls of yellow paper. It was certainly true that teletypes were an important part of the many communications networks that were strung together over the 20th century, but these noisy, greasy beasts had their day and are now largely museum pieces.

Which is exactly where the ancient Model 19 Teletype machine that [CuriousMarc] and company are restoring is destined. Their ongoing video series, six parts long as of this writing, documents in painstaking detail how this unit worked and how they are bringing it back to its 1930s glory. Teletypes were made to work over telephone lines with very limited bandwidth, and the hacks that went into transmitting text messages with a simple 5-bit encoding scheme are fascinating. The series covers the physical restoration of the machine, obviously well-loved during its long service with the US Navy. Of particular interest is the massive power supply with its Thyratron tubes and their mysterious blue glow.

The whole series is worth a watch if you’re even slightly interested in retrocomputing. We’re particularly taken with the mechanical aspects of these machines, though, which have a lot in common with mechanical calculators. [Al Williams] recently covered the non-replacement of the power supply caps for this unit, which is an interesting detour to this restoration.

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Amiga Repairs Put One Tough Little Machine Back In Service

July 30, 2018 by 8 Comments

Returning a piece of retro hardware to factory condition is generally a labor of love for the restorationist. A repair, on the other hand, is more about getting a piece of equipment back into service. But the line between repair and restoration is sometimes a fine one, with the goals of one bleeding over into the other, like in this effort to save an otherwise like-new Amiga 2000 with a leaky backup battery.

Having previously effected emergency repairs to staunch the flow of electrolyte from the old batteries and prevent further damage, [Retromat] entered the restoration phase of the project. The creeping ooze claimed several caps and the CPU socket as it spread across the PCB, but the main damage was to the solder resist film itself. In the video below you can clearly see flaky, bubbly areas in the mask where the schmoo did its damage.

Using a fiberglass eraser, some isopropyl alcohol, and far more patience than we have, [Retromat] was able to remove the damaged resist to reveal the true extent of the damage below. Thankfully, most of the traces were still intact; only a pair of lines under the CPU socket peeled off as he was removing it. After replacing them with fine pieces of wire, replacing the corroded caps and socket, and adding a coin-cell battery holder to replace the old battery, the exposed traces were coated with a varnish to protect them and the machine was almost as good as new.

Amigas were great machines in their day and launched more than one business. They’ve proved their staying power too, some even in mission-critical roles.

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