A short but highly detailed documentary by [Krzysztof Tyszecki] explores the split-flap display system in place at the Łódź Kaliska train station in Poland as well as the efforts needed by the staff to keep it running and useful to this day. Split-flap displays might be old technology, but many are still in use throughout the world. But even by those standards, the unit at Łódź Kaliska is a relic you wouldn’t expect to see outside a museum. “I doubt you’ll find an original anywhere else,” says a staff member. It requires constant upkeep to remain operational, and meeting the changing demands of a modern station within the limitations of the original system takes some cleverness. “In general the failure rate of the device is terrible,” he adds.
The system runs on punch cards. You can’t buy them anymore, so a local printer makes them – several hundred are needed every time there is a schedule change. The punching pliers (which also can no longer be purchased) get so worn out they replace the pins with custom-made ones from a local locksmith. The moving parts of the card reader have split-pins which need to be replaced every week or two – the stress of repeated movement simply wears them away. There’s nothing to do but replace them regularly. The assembly needs regular cleaning since dust accumulates on the cards and gets into the whole assembly. The list goes on… and so does the station.
There is no computation in the modern sense – it’s an electromechanical signing system managed and updated by human operators. It has more in common with a crossbar switch based telephone exchange than anything else. The punch cards are just a means of quickly, accurately, and repeatedly setting the displays to known states.
The short documentary goes into a lot of detail about every part of the system. The cards themselves are described in detail (1:07), as is the operator’s routine (2:27). We even see the back end controller (9:41), as well as see a split-flap module taken apart and tested (14:33) with an old tester the staffer isn’t sure will even work – but as with everything else we see, of course it does.
There was a time in the late 80s and early 90s where the Amiga was the standard for computer graphics. Remember SeaQuest? That was an Amiga. The intro to Better Call Saul? That’s purposefully crappy, to look like it came out of an Amiga. When it comes to the Amiga and video, the first thing that comes to mind is the Video Toaster, hardware and software that turns an Amiga 2000 into a nonlinear video editing suite. Digital graphics, images, and video on the Amiga was so much more than the Video Toaster, and at this year’s Vintage Computer Festival East, [Bill] and [Anthony] demonstrated what else the Amiga could do.
If you have a computer on your desk today, the chances are that it has an Intel architecture and is in some way a descendant of the IBM PC. It may have an Apple badge on the front, it may run Linux, or Windows, but in hardware terms the overwhelming probability is that it will be part of the Intel monoculture. A couple of decades ago though in the 16- and early 32-bit era you would have found a far greater diversity of architectures. Intel 3-, and 486s in PCs and clones, Macintosh, Commodore, and Atari platforms with the 68000 family, the WDC 65C816 in the Apple IIGS, and the Acorn Archimedes with an early ARM processor to name but a few.
In the tough environment of the 1990s most of these alternative platforms fell by the wayside. Apple survived to be revitalised under a returning Steve Jobs, Atari and Commodore withered under a bewildering succession of takeovers, and Acorn split up and lost its identity with its processor licensing subsidiary going on to power most of the mobile devices we take for granted today.
While the official history of the digital camera begins with a Kodak engineer tinkering around with digital electronics in 1975, the first digital camera was actually built a few months prior. At the Vintage Computer Festival East, [William Sudbrink] rebuilt the first digital camera. It’s wasn’t particularly hard, either: it was a project on the cover of Popular Electronics in February, 1975.
[William]’s exhibit, Cromemco Accessories: Cyclops & Dazzler is a demonstration of the greatest graphics cards you could buy for S-100 systems and a very rare, very weird solid-state TV camera. Introduced in the February, 1975 issue of Popular Electronics, the Cyclops was the first digital camera. This wasn’t a device that used a CCD or a normal image sensor. The image sensor in the Cyclops was a 1 kilobit DRAM from MOS, producing a digital image thirty-two pixels square.
The full description, schematic, circuit layout, and theory of operation are laid out in the Popular Electronics article; all [William] had to do was etch a PCB and source the components. The key part – a one kilobit MOS DRAM in a metal can package, carefully decapsulated – had a date code of 1976, but that is the newest component in the rebuild of this classic circuit.
To turn this DRAM into digital camera, the circuit sweeps across the rows and columns of the DRAM array, turning the charge of each cell into an analog output. This isn’t a black or white camera; there’s gray in there, or green if you connect it to an oscilloscope.
This project in Popular Electronics would be manufactured by Cromemco in late 1975 and was released as their first product in January, 1976. The Cromemco was marketed as a digital camera, designed to interface with the MITS Altair 8800 computer, allowing anyone to save digital images to disk. This was the first digital camera invented, and the first digital camera sold to consumers. It’s an amazing piece of history, and very happy [William] was able to piece this together and bring it out to the Vintage Computer Festival this weekend.
[Limpkin] has an idea for a project that uses a lot of IN-9 Nixie tubes. Where a Nixie tube clock would only use four or six tubes, [Limpkin] is looking at fifty IN-9 bar graph Nixie tubes. These tubes only light up above 100 Volts and draw about half an amp. That’s 64 Watts, according to the math on the project page, so how does [Limpkin] plan on powering these tubes? With a big high voltage power supply.
The power supply [Limpkin] designed is more or less what you would expect to find in any power supply. There’s a transformer, a bunch of caps, and a rectifier. Going with a standard laminated core transformer would mean this power supply would be huge and heavy, but once again eBay comes to the rescue with a small, 150 Watt toroidal transformer. The largest output on the transformer was two 24 V outputs. Combining those outputs gets [Limpkin] to 48V AC, or 68V peak to peak. A full wave voltage doubler with two caps and two diodes gives [Limpkin] the 136V DC that will power the tubes.
Combine the high voltage circuit with a 9V AC tap, a small bridge rectifier, and a few more caps, and [Limpkin] had a supply that would power the tubes and the rest of the electronics in his multiple Nixie tube project. A few passes with a CNC mill gave the power supply a nice case topped off with a foreboding toroidal transformer ready to power a beautiful neon project.
If you’ve got an old calculator, Commodore 64, or any other device that used a tape recorder to store and retrieve data, you’ve probably also got a bunch of cassettes lying around, right? Well, you can get rid of them now (or sell them to nostalgic collectors for outrageous prices) because you can just as easily dump them to Audacity, decode them and archive them on a more sane medium.
In [Kai]’s case, the computer was a Sharp Pocket Computer system, and in his post there’s a lot of detail that’s specific to that particular system. If that’s applicable to you, go read up. In particular, you’ll be glad to find that the Pocket-Tools is a software suite that will encode and decode files between the Sharp binary formats and audio. Along the way, we found similar tools for Casio pocket computers too.
For a more general-purpose approach, like if you’re trying to dump and load data from a more standard computer that uses 1200/2400 Hz FSK encoding, this Python library may be useful, or you can implement the Goerzel algorithm yourself on your platform of choice. If you’ve got a particular binary format in mind, though, you’ll have to do the grunt work yourself.
Anyone out there still using these audio data encodings? We know that ham radio’s APRS system runs on two tones. What else? Why and when would you ever transfer data this way these days?
Some presentations get a bit technical, which isn’t bad, but what is so interesting about this one is the clear explanation of what the market was like, and what it was like for the user during this time. For example, one bit we found really interesting was the mention of later games not supporting some of the neat color hacks for CGA because they couldn’t emulate it fully on the VGA cards they were developing on. Likewise, It was interesting to see why a standard like RGBI even existed in the first place with his comparison of text in composite, and much clearer text in RGBI.
We learned a lot, and some mysteries about the bizarre color choices in old games make a lot more sense now. Video after the break.