2:3 Scale VT100 Is A Perfect Pairing For PDP-8/I Replica

When he went shopping for a vintage serial terminal to go along with his reproduction PDP-8/I computer, [Michael Gardi] came down with a bad case of sticker shock. But rather than be discouraged, he reasoned that if his “retro” computer could stand to have modern components at its heart, so could the terminal he used to talk to it. Leaning on his considerable experience in designing 3D printed replica hardware, he’s built an absolutely gorgeous scaled down DEC VT100 terminal that any classic computer aficionado would be happy to have on their desk.

Now to be clear, [Michael] hasn’t created a true serial terminal. Since the faux PDP-8/I is running on a Raspberry Pi, all he needed to do was come up with something that could connect to its HDMI and USB ports. Put simply, he’s essentially just made a 3D printed enclosure for the Pi’s monitor and keyboard. Oh, but what a gorgeous enclosure it is.

Recreating the VT100 in CAD was made more difficult by the fact that [Michael] couldn’t get his hands on the authentic hardware. But of course, that’s never stopped him before. It turns out DEC provided some very detailed dimensions for the terminal in their original documentation, and while comparing them to photographs of the actual terminal did uncover a few key differences, the overall look is spot on. Once the design was done, he reports it took two rolls of filament and more than 200 hours to print out all the parts for the enclosure.

To help sell the authentic look [Michael] tracked down a 4:3 LCD of the appropriate size, and the use of an off-the-shelf portable mechanical keyboard should make text entry a pleasure. For a little fun, he even came up with a themed arcade controller for the VT100 that can be used with RetroPie. The printed logo plate is an especially nice touch, and we’re more than willing to forgive the fact that he had to print it at a larger scale than the rest of the terminal to get all the detail in with his printer’s 0.4 mm nozzle.

On a technical level, this is perhaps the most straightforward replica we’ve ever seen from [Michael]. But even on a relatively simple project like this, his signature attention to detail and craftsmanship is on full display. It’s always a good day when he’s got a new build to show off with, and we’re eager to see what he comes up with next.

Altair Front Panel Tutorials

If you aren’t old enough to remember when computers had front panels, as [Patrick Jackson] found out after he built a replica Altair 8800, their operation can be a bit inscrutable. After figuring it out he made a pair of videos showing the basics, and then progressing to a program to add two numbers.

Even when the Altair was new, the days of front panels were numbered. Cheap terminals were on their way and MITS soon released a “turnkey” system that didn’t have a front panel. But anyone who had used a minicomputer from the late 1960s or early 1970s really thought you needed a front panel.

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Bare Metal Programming With Only Three Buttons

For anyone who’s seen a 1970’s era microcomputer like the Altair 8800 doing its thing, you’ll know the centerpiece of these behemoths is the array of LEDs and toggle switches used as input and output. Sure, computers today are exponentially more capable, but there’s something undeniably satisfying about developing software with pen, paper, and the patience to key it all in.

If you’d like to get a taste of old school visceral programming, but aren’t quite ready to invest in a 40 year old computer, then [GClown25] might have the answer for you. He’s developed a pocket sized “computer” he’s calling the BIT4 that can be programmed with just three tactile switches. In reality it’s an ATMega4809 running C code, but it does give you an idea of how the machines of yesteryear were programmed.

In the video after the break, [GClown25] demonstrates the BIT4 by entering in a simple binary counter program. With a hand-written copy of the program to use as a reference, he steps through the memory addresses and enters in the command and then the value he wishes to operate on. After a few seconds of frantic button pushing, he puts the BIT4 into run mode and you can see the output on the array of LEDs along the top edge of the PCB.

All of the hardware and software is open source for anyone who’s interested in building their own copy, or perhaps just wants to take a peak at how [GClown25] re-imagined the classic microcomputer experience with modern technology. Conceptually, this project reminds us of the Digirule2, but we’ve got to admit the fact this version isn’t a foot long is pretty compelling.

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World’s Oldest Computer Festival Is This Weekend

There was a time when owning a home computer was kind of a big deal. In the days before the popularization of the Internet, so-called “computer shows” were the best way to meet with others to swap advice, information, and hardware. Of course today, things are very different. The kind of people who are building their computers just buy the parts online, and everyone else is probably using a $200 laptop from Walmart that isn’t worth spending the time or money on to upgrade.

Small sampling of the talks at TCF 2019

So while the Trenton Computer Festival (TCF) may have started in 1976 as a way for people to buy early computers like the Altair 8800, over the years it has morphed into something much closer to the modern idea of a “con”. Those who visit the 44th TCF on March 23rd at the College of New Jersey will likely spend most of their time at the festival attending the 40+ talks and workshops that will be happening in a span of just six hours. But anyone who’s got some cash to burn can still head over to the flea market area where they’ll be able to buy both modern and vintage hardware.

Talks run the gamut from Arduino to quantum computing, and if you don’t see something that piques your interest in this year’s program, one might wonder how you found yourself reading Hackaday in the first place. If you manage to find some spare time between all the talks, the New Jersey chapter of the The Open Organisation Of Lockpickers (TOOOL) will be there giving a hands-on lock picking class, and if you don’t mind taking the crash course, you can even get your ham radio license. All for the princely sum of just $20 at the door.

In fact, there’s so much going on at TCF that it can be somewhat overwhelming. As I found out during my visit last year, the number of simultaneous events means you’ll almost certainly have some difficult decisions to make. I’ll be making the trip out to the College of New Jersey campus again this year for TCF, and will have plenty of Hackaday stickers and buttons to give out to anyone who manages to stop me while I dash between talks.

Blowing The Dust Off Of An IBM AS/400 Server

If you’ve never seen an IBM AS/400 machine, don’t feel bad. Most people haven’t. Introduced in 1988 as a mid-range server line, it used a unique object-based operating system and was geared specifically towards business and enterprise customers. Unless you’re a particularly big fan of COBOL you probably won’t have much use for one today, but that doesn’t mean they aren’t worth playing around with if the opportunity presents itself.

So when a local IT company went belly up and was selling their old hardware, including a late 90’s era IBM AS/400e Series, [Rik te Winkel] jumped at the chance to take this unique piece of computing history home. He knew it was something of a risk, as maintenance and repair tasks for these machines were intended to be done by IBM certified technicians rather than the DIYer, leaving little in the way of documentation or even replacement parts. But in the end it worked out, and best of all, he documented the successful process of dragging this 90’s behemoth into the blinding light of the twenty-first century for all the world to see.

After getting the machine home and sitting through its thirty minute boot process, [Rik] was relieved to see the code 01 B N pop on the server’s display. This meant the system passed all the internal checks and was ready to go, he just had to figure out how to talk to the thing. Built to be a pure server, the machine didn’t offer any video output so he’d have to log into it over the network.

[Rik] noted that there was no new DHCP entry in his router for the server, but of course that was hardly surprising as the machine would have certainly had a static IP when it was in use. So he shut the server down, plugged it directly into his laptop’s Ethernet port, and watched the output of Wireshark as it went through its arduous boot sequence. Eventually he started to pick up packets coming from the IP address, and he had his target.

There are a few clients out there that allow you to remotely log into an AS/400, so he downloaded one and pointed it to the server’s IP. He was surprised to see the operating system was apparently in Dutch, but at least he was in. He tried a few common usernames and passwords, helped along by the fact that this OS from a somewhat more innocent era will actually tell you if you have the username right or wrong, and eventually managed to hack the Gibson with the classic admin/admin combo.

So he was in, but now what? [Rik] decided that he couldn’t truly call this machine bested until he could pull up the Hackaday Retro Edition, so he started work on writing a program to let him pull down the page directly on the AS/400 in IBM’s proprietary Report Program Generator (RPG) programming language. You know, as one does. He didn’t quite feel up to writing a whole HTML parser, but he got as far as generating a HTTP GET request, downloading the page’s source, and opening it up as a local file. That’s good enough for us.

Our very own [Al Williams] documented his adventures poking around an Internet-connected AS/400 machine, which might serve as a helpful primer if you ever find one of these delightfully oddball computers kicking around the local recycling center.

Rebuilding An Amiga 500 PSU

One of the challenges of keeping a vintage computer up and running is the limited availability of spare parts. While not everything has hit dire levels of availability (not yet, anyway), it goes without saying that getting a replacement part for a 30+ year old computer is a bit harder than hitting up the local electronics store. So the ability to rebuild original hardware with modern components is an excellent skill to cultivate for anyone looking to keep these pieces of computing history alive in the 21st century.

This is in ample evidence over at [Inkoo Vintage Computing], where repairs and upgrades to vintage computers are performed with a nearly religious veneration. Case in point: this detailed blog post about rebuilding a dead Amiga 500 power supply. After receiving the machine as a donation, it was decided to attempt to diagnose and repair the PSU rather than replace it with a newly manufactured one; as much for the challenge as keeping the contemporary hardware in working order.

What was found upon opening the PSU probably won’t come as a huge surprise to the average Hackaday reader: bad electrolytic capacitors. But these things weren’t just bulged, a few had blown and splattered electrolyte all over the PCB. After removing the bad caps, the board was thoroughly inspected and cleaned with isopropyl alcohol.

[Inkoo Vintage Computing] explains that there’s some variations in capacitor values between different revisions of the Amiga PSU, so it’s best to match what your own hardware had rather than just trying to look it up online. These capacitors in particular were so old and badly damaged that even reading the values off of them was tricky, but in the end, matching parts were ordered and installed. A new fuse was put in, and upon powering up the recapped PSU, the voltages at the connector were checked to be within spec before being plugged into the Amiga itself.

As a test, the Amiga 500 was loaded up with some demos to really get the system load up. After an hour, the PSU’s transformer was up to 78°C and the capacitors topped out at 60°C. As these parts are rated for 100°C (up from 85°C for the original parts), everything seemed to be within tolerances and the PSU was deemed safe for extended use.

This sort of repair isn’t exactly rare with hardware this old, and we’ve seen similar work done on a vintage Apple power supply in the past. If you’re less concerned with historical accuracy, [Inkoo Vintage Computing] has also shown off adapting an ATX PSU for use with the Amiga.

Recreating The Amiga 1200 PCB From Pictures

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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