Despite his best efforts to repair the LCD on his Casio FX-702P, it soon became clear to [Andrew Menadue] that it was a dead-end. Rather than toss this relatively valuable device in the trash, he wondered if would be possible to replace the LCD with a more modern display. Knowing that reverse engineering the LCD panel itself would be quite a challenge, he decided instead to focus his efforts on decoding the communications between the calculator’s processor and display controller.
With his logic analyzer connected to the Casio’s four bit bus [Andrew] was able to capture a sequence of bytes during startup that looked promising, although it didn’t quite make sense at first. He had to reverse the order of each nibble, pair them back up into bytes, and then consult the FX-702P’s character map as the device doesn’t use ASCII. This allowed him to decode the message “READY”, and proved the concept was viable.
Of course a calculator with a logic analyzer permanently attached to it isn’t exactly ideal, so he started work on something a bit more compact. Armed with plenty of display controller data dumps, [Andrew] wrote some code for a STM32 “Blue Pill” ARM Cortex M3 microcontroller that would sniff and decode the data in near real-time. In the video after the break you can see there’s a slight delay between when he pushes a button and when the corresponding character comes up on the LCD below, but it’s certainly usable.
Unfortunately, the hardware he’s created for this hack is just slightly too large to fit inside the calculator proper. The new LCD is also nowhere near the size and shape that would be required to replace the original one. But none of that really matters. While [Andrew] says he could certainly make the electronics smaller, the goal was never to restore the calculator to like-new condition. Sometimes it’s more about the journey than the destination.
When it comes to building sets and props for movies and TV, it’s so easy to get science fiction wrong – particularly with low-budget productions. It must be tempting for the set department to fall back on the “get a bunch of stuff and paint it silver” model, which can make for a tedious experience for the technically savvy in the audience.
But low-budget does not necessarily mean low production values if the right people are involved. Take [Joel Hartlaub]’s recent work building sets for a crowdfunded sci-fi film called Infinitus. It’s a post-apocalyptic story that needed an underground bunker with a Fallout vibe to it, and [Joel] jumped at the chance to hack the sets together. Using mainly vintage electronic gear and foam insulation boards CNC-routed into convincing panels, he built nicely detailed control consoles for the bunker. A voice communicator was built from an old tube-type table radio case with some seven-segment displays, and the chassis of an old LCD projector made a convincing portable computer terminal. The nicest hack was for the control panel of the airlock door. That used an old TDD, or telecommunications device for the deaf. With a keyboard and a VFD display, it fit right into the feel of the set. But [Joel] went the extra mile to make it a practical piece, by recording the modulated tones from the acoustic coupler and playing them back, to make it look as if a message was coming in. The airlock door looks great too.
Like many hacks, it’s pretty impressive what you can accomplish with a deep junk pile and a little imagination. But if you’ve got a bigger budget and you need some computer displays created, we know just the person for the job.
When [Kerry Wong] found an Amrel PPS 35-2 Programmable Power Supply from the late 90s on eBay, he recognized it as the single-channel version of another unit he owned, the dual-channel Amrel PPS-2322. Naturally, he purchased it and did a compare and contrast of the two models.
From the outside, they look fairly different but weigh about the same. But the similarities on the inside make it quite clear that they share a common design. There are a few things that grab your eye and the 35-2 doesn’t seem quite as well thought out, with some components being soldered into awkward-looking places. Capacitors bristle like barnacles where they are soldered directly to a connector, and a blob of hot glue anchors two resistors that rise up out of the board like a couple of weeds.
Recently [iot4c] stumbled upon this gorgeous Robotron Reiss plotter from 1989, brand-new and still in its original box. Built before the fall of the Berlin Wall in East Germany, it would be a crime to allow such a piece of computing history to go unused. But how to hook it up to a modern system? Bad enough that it uses some rather unusual connectors, but it’s about to be 2020, who wants to use wires anymore? What this piece of Cold War hardware needed was an infusion of Bluetooth.
While the physical ports on the back of the Robotron certainly look rather suspect, it turns out that electrically they’re just RS-232. In practice, this means converting it over was fairly straightforward. With a Bolutek BK3231 Bluetooth module and an RS-232 to UART converter, [iot4c] was able to create a wireless adapter that works transparently on the plotter by simply connecting it to the RX and TX pins.
A small DC buck converter was necessary to provide 3.3 V for the Bluetooth adapter, but even still, there was plenty of room inside the plotter’s case to fit everything in neatly. From the outside, you’d have no idea that the hardware had ever been modified at all.
But, like always, there was a catch. While Windows had no trouble connecting to the Bluetooth device and assigning it a COM port, the 512 byte buffer on the plotter would get overwhelmed when it started receiving commands. So [iot4c] wrote a little script in Node.js that breaks the commands down into more manageable chunks and sends them off to the plotter every 0.1 seconds. With this script in place the Robotron moved under its own power for the first time in ~30 years by parsing a HP-GL file generated by Inkscape.
It’s easy to take power supplies for granted in modern computing, but powering vintage hardware is not always so simple or worry-free. The power supplies for old electronics are themselves vintage, and the hardware being powered can be quite precious. A power problem can easily cause fried components and burned traces on a board. As [Doc TB] observes, by the time you hear crackling, it’s already far too late.
To address this, [Doc TB] designed the ATX2AT Smart Converter as an open source project and recently decided to make it available through a Kickstarter campaign. ATX2AT is a way to safely and securely replace some vintage power supplies with a standard PC ATX power supply, and adds a large number of protection features such as current monitoring and programmable reaction time for overcurrent protection. All of this can help prevent a retrocomputer enthusiast’s precious vintage hardware from being damaged in the event of a problem. It’s not just for powering known-good hardware; it can be invaluable when testing or repairing hardware that might be in an unknown state.
When we first came across [Doc TB]’s ATX2AT project we recognized it as a well-made device to address a specific niche, and to do it well. Assessing risk takes into account not only the probability of a problem occurring, but also just how bad things would be if it did happen. If your old hardware is precious enough to warrant the extra protection, or you are into repairing or assessing old hardware, then an ATX2AT might be just what you need. You can see it in action in the video embedded below.
We know that a lot of our beloved readers don’t take kindly to abuse of vintage hardware, so the Atari fans in the audience may want to avert their eyes for this one. Especially if they’re particularly keen on spinning up their Jawbreaker cassette on authentic hardware, as [iot4c] has gutted an Atari XC12 Program Recorder to turn it into an enclosure for a Raspberry Pi video storage device.
Step one of this conversion was, as you might expect, removing all the original hardware from the cassette recorder case. From there, [iot4c] fitted the Raspberry Pi, a USB hard drive, and a YDS-5A DC-DC converter to power them. Depending on what the drive setup looks like, it might also make sense to add a USB powered hub. A length of Ethernet cable was left hanging out the back of the Atari XC12 so it could be plugged into the network, but a panel mount RJ45 connector could spruce things up a bit.
Of course, gutting an old piece of hardware and sticking a Pi into it isn’t exactly breaking any new ground at this point. But we did appreciate that [iot4c] went the extra mile to wire it up so the “Save” LED now doubles as a network activity indicator. Which pretty much brings it full circle in terms of functionality for a network-attached video recorder.
Earlier in the year [iot4c] converted a 65XE into a USB keyboard with the help of an Arduino Leonardo, but the vintage Atari aficionados will be happy to note that at least in that case the donor machine remained fully functional.
[Ken Shirriff] recently shared some pictures and a writeup from his visit to the Large Scale Systems Museum, a remarkable private collection of mainframes and other computers from the 1970s to the 1990s. Housed in a town outside Pittsburgh, it contains a huge variety of specimens including IBM mainframes and desk-sized minicomputers, enormous disk and tape storage systems, and multiple 90s-era Cray supercomputers. It doesn’t stop there, either. Everything through the minicomputer revolution leading to personal home computers is present, and there are even several Heathkit HERO robot kits from the 80s. (By the way, we once saw a HERO retrofitted with wireless and the ability to run Python.)
Something really special is that many of the vintage systems are in working order, providing insight into how these units performed and acted. The museum is a private collection and is open only by appointment but they encourage interested parties not to be shy. If a trip to the museum isn’t for you, [Ken] has some additional photos from his visit here for you to check out.