retrocomputing

334 Articles

MS-DOS Meets The Fediverse

August 9, 2023 by 30 Comments

By now, most Windows users are set up with decently functional machines running Windows 10 or 11. Of course there are a few legacy machines still lagging behind on Windows 7 or 8 and plenty of computers in industrial settings running ancient proprietary software on Windows XP. But only the most hardcore of IBM PC users are still running DOS, and if you have eschewed things like Unix for this command-line operating system this long you might want to try using it to get online in the Fediverse with Mastodon.

The first step is getting DOS 6.22, the most recent version released in 1994, set up with all the drivers and software needed to access the Internet. At the time of its release there were many networking options so the operating system didn’t include these tools by default. [Stephen] first sets up an emulated NE2000-compatible networking card and then installs the entire TCP/IP stack and then gets his virtual machine set up with an IP address.

With a working Internet connection set up, the next step on the path of exploring federated social media is to install DOStodon (although we might have favored the name “MastoDOS”) which is a Mastodon client specifically built for MS-DOS by [SuperIlu]. There are pre-compiled packages available on its GitHub page for easy installation in DOS but the source code is available there as well. And, if this is your first time hearing about the Fediverse, it is mostly an alternative to centralized social media like Facebook and Reddit but the decentralization isn’t without its downsides.

A Cycle-Accurate Sega Genesis With FPGA

August 4, 2023 by 17 Comments

The Field-Programmable Gate Array (FPGA) is a powerful tool that is becoming more common across all kinds of different projects. They are effectively programmable hardware devices, capable of creating specific digital circuits and custom logic for a wide range of applications and can be much more versatile and powerful than a generic microcontroller. While they’re often used for rapid prototyping, they can also recreate specific integrated circuits, and are especially useful for retrocomputing. [nukeykt] has been developing a Sega Genesis clone using them, with some impressive results.

The Sega Genesis (or Mega Drive) was based around the fairly common Motorola 68000 processor, but this wasn’t the only processor in the console. There were a number of coprocessors including a Z80 and several chips from Yamaha to process audio. This project reproduces a number of these chips which are cycle-accurate using Verilog. The chips were recreated using images of de-capped original hardware, and although it doesn’t cover every chip from every version of the Genesis yet, it does have a version of the 68000, a Z80, and the combined Yamaha processor working and capable of playing plenty of games.

The project is still ongoing and eventually hopes to recreate the rest of the chipset using FPGAs. There’s also ongoing testing of the currently working chips, as some of them do still have a few bugs to work out. If you prefer to take a more purist approach to recreating 90s consoles, though, we recently featured a project which reproduced a Genesis development kit using original hardware.

Thanks to [Anonymous] for the tip!

Apple III Slows Down To Smell The Roses

August 3, 2023 by 7 Comments

The most collectible items in the realm of vintage computers often weren’t the most popular of their era. Quite the opposite, in fact. Generally the more desireable systems were market failures when they first launched, and are now sought out because of a newly-appreciated quirk or simply because the fact that they weren’t widely accepted means there’s fewer of them. One of the retro computers falling into this category is the Apple III, which had fundamental hardware issues upon launch leading to a large recall and its overall commercial failure. [Ted] is trying to bring one of these devices back to life, though, by slowing its clock speed down to a crawl.

The CPU in these machines was a Synertek 6502 running at 1.8 MHz. With a machine that wouldn’t boot, though, [Ted] replaced it with his own MCL65+, a purpose-built accelerator card based on the 600 MHz Teensy 4.1 microcontroller in order to debug the motherboard. The first problem was found in a ROM chip which prevented the computer loading anything from memory, but his solution wouldn’t work at the system’s higher clock speeds. To solve that problem [Ted] disabled the higher clock speed in hardware, restricting the system to 1 MHz and allowing it to finally boot.

So far there haven’t been any issues running the computer at the slower speed, and it also helps keep the computer cooler and hopefully running longer as well, since the system won’t get as hot or unstable. This isn’t [Ted]’s first retrocomputing rodeo, either. His MCL chips have been featured in plenty of other computers like this Apple II which can run at a much faster rate than the original hardware thanks to the help of the modern microcontroller.

Retro Gadgets: The Real Desktop Computer

July 24, 2023 by 27 Comments

People argue about the first use of the computer desktop metaphor. Apple claims it. Xerox probably started it. Yet, when I think of computer desktops, I think of the NOVAL 760. Not a household name, to be sure, but a big ad spread in a June 1977 Byte magazine was proud to introduce it. At $2995, we doubt many were sold, but the selling point was… well… it was built into a “handsome wood desk, designed to compliment any decor.” The desk folded down when you were not using the computer, and the keyboard recessed into a drawer.

The computer itself was no slouch for 1977, but nothing you couldn’t find elsewhere. An 8080, speed unspecified, had 16 kB of RAM and 3 kB of PROM. There was also a display with a few kB of memory hanging around, too. And just in case you were worried, the bottom of the page entitled “The Ultimate in Home Computers” reads, “The NOVAL 760 COMPUTER. A fully-assembled, fully-tested personal computer … not a kit!” Of course, for us, that’s not really a selling point. If you wonder why the computer was memory limited, this is the time that Extensys bragged in an ad: 64 kB for $1495! If you ordered one, you could have it in 15 to 30 days, too!

There were options for more memory, and it wasn’t clear how many of the I/O devices in the ad were actually included in the advertised price. Some of the devices seemed very specialized, so we are guessing the basic system didn’t include some of them.

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PCjr WebServer Hits 2500 Hours Uptime

July 20, 2023 by 23 Comments

When [Mike] fired up his PCjr webserver back in March, he probably wasn’t expecting it to go viral. 2640 hours later, here we are! Not only has his machine run continuously for over 110 days, it also is surviving a global hug of death. All of this is thanks to some very special software.

We see lots of old machines here on Hackaday. We also see lots of minimal web servers. But we don’t see many that can run for thousands of hours, offering up to 8 simultaneous connections. Curious if jr is still up? Check brutmanlabs.org. The whole website is hosted on the 40-year-old machine. If you want to be a bit more kind, here’s a direct link to the text-only status page. While many of those hours were idle, currently lots of folks are hitting that little V20 CPU, so please give it a few seconds to respond.

The PCjr has a few upgrades — the aforementioned V20 CPU upgrade, a jrIDE sidecar, and a memory upgrade to 736 kB to name a few.  Ethernet connectivity is via a Xircom parallel port adapter – which is circa 1993.  The operating system is IBM PC DOS 5.02. One thing to note is that all these upgrades were possible back in the mid-1980’s when the PCjr was still current.  [Mike] could run the system with an MFM hard drive, an ISA ethernet card (via an adapter), and use the original CRT monitor. Older DOS versions would work too — though partition sizes would be limited. The “modern” conveniences are just to keep from wearing out vintage hardware which is quickly becoming rare.

The real glue that holds this all together is [Mike’s] own software: mTCP. mTCP is a full set of tools for running internet applications on systems running MS-DOS or a compatible OS. We’ve seen quite a few mTCP projects over the years.  [Mike] has worked tirelessly testing the software, ensuring that it is stable and reliable.

Software is never perfect though – one thing [Mike] didn’t implement is a log roller. Since he has logging turned on, the PCjr was slowly filling up its hard drive. Once the drive was full, mTCP would perform an orderly shutdown — but the uptime will be reset.  [Mike] was able to go in and switch off logging with  DOS’s DEBUG command. A live patch is not the way one would normally update software – but the fact that he was able to do it shows how deep [Mike’s] knowledge of the software goes.

[Mike] has even provided a live stream recording of the little PCjr handling requests from all over the globe.

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Building A MiniPET Is Better With Friends

July 17, 2023 by 4 Comments

[Taylor and Amy] love taking on retro computer projects. This week they’re building a MiniPET from Tynemouth and The Future is 8 Bit.  It’s a pretty awesome kit which sadly isn’t available anymore. Taylor bought one of the last ones as part of a charity sale at the 2023 Vintage Computer Festival Southwest.

If you haven’t seen their YouTube channel yet, check it out! The two have been best friends since 1984. Their channel has just the right mix of education and comedy, with pacing fast enough to keep things interesting. It’s really refreshing to see two people enjoying a project together.

The MiniPET is of course a reproduction of the hardware in the Commodore PET, the machine which predated the VIC-20 and of course the Commodore 64. The kit starts with installing a few discrete parts — resistors,  capacitors, and diodes.  Then come the IC sockets. [Taylor and Amy] ran into a bit of trouble when it came time to install the chips. While installing the 40-pin 65C21 Peripheral Interface Adapter (PIA), one pin bent under the socket. [Taylor] popped the chip back out, and replaced it — which resulted in 3 bent pins!

Anyone who’s installed new DIP parts has been through this. The pins are always bent out a bit from the factory. The old “Bend it in using a table” method usually works — but if you want perfect pins, try a pin straightener. These versatile tools can even be 3D printed.

Once the pin problems are solved, it’s time to power up the kit and see if it will work.  That’s when we get to see that magic moment when a project first comes to life. Check out the video – you’ll see what we mean.

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Reverse-Engineering Helps Typesetting Machine Punch Paper Tape Again

July 11, 2023 by 14 Comments

[Scott M. Baker] wants a paper tape punch for his retrocomputer collection. That’s fine with us, we don’t judge. In fact,  these electromechanical peripherals from the past have a lot going for them, especially the noise. But alas, such things are a little hard to come by these days, and rolling one from scratch would be a difficult proposition indeed. What to do?

Luckily, we live in the future, and eBay holds all sorts of wonders, including these typesetter keyboards from the 1970s, which [Scott] promptly reverse-engineered. We’ll get to the details in a minute, but first, can we just take a moment to think about the workflow these things were part of? These aren’t terminals — they lack any kind of IO apart from the punched paper tape they spewed out. The operator’s job was to punch in copy without any kind of feedback that they were hitting the right keys, and just sent the paper tap record of the session off to the typesetting machines. And you think your job sucks.

To give this thing an interface, [Scott] first had to revive the power supply, whose capacitors had seen sunnier days. With that out of the way, he set about understanding the CPU-less machine by analyzing its 7400-series logic, as well as planning how to make the native 6-bit output into a more manageable 8-bit. Thankfully, the tape punch already had solenoids for the top two bits, but finding a way to drive them wasn’t trivial.

The solution was to bypass a buffer so that the bits for the desired character can be set with a Raspberry Pi and an ATF22V10 programmable logic device. That’s enough to force the punch to do its thing; actually getting it to talk to something else, perhaps even [Scott]’s Heathkit H-8 computer.

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