Magnetic tape storage is something many of us will associate with 8-bit microcomputers or 1960s mainframe computers, but it still has a place in the modern data center for long-term backups. It’s likely not to be the first storage tech that would spring to mind when considering a relay computer, but that’s just what [DiPDoT] has done by giving his machine tape storage.
We like this hack, in particular because it’s synchronous. Where the cassette storage of old just had the data stream, this one uses both channels of a stereo cassette deck, one for clock and the other data. It’s encoded as a sequence of tones, which are amplified at playback (by a tube amp, of course) to drive a rectifier which fires the relay.
On the record side the tones are made by an Arduino, something which we fully understand but at the same time can’t help wondering whether something electromechanical could be used instead. Either way, it works well enough to fill a relay shift register with each byte, which can then be transferred to the memory. It’s detailed in a series of videos, the first of which we’ve paced below the break.
If you want more cassette tape goodness, while this may be the slowest, someone else is making a much faster cassette interface.
“Magnetic tape storage is something many of us will associate with 8-bit microcomputers or 1960s mainframe computers, but it still has a place in the modern data center for long-term backups.”
Something like cold storage. Maybe one of these days we’ll get holographic storage.
As for holographic storage, there have been a few attempts…
InPhase Technologies: InPhase Technologies was a prominent company that developed and marketed holographic storage solutions. They worked on products like the Tapestry drive, which aimed to store data on a 5 1/4-inch disc. In 2008, InPhase introduced the Tapestry 300R, offering a 300 GB capacity and 20 MB/s read/write transfer rates for professional archiving. The company also had a product roadmap that aimed for significantly higher capacities and transfer rates in subsequent generations. InPhase developed special media like their Tapestry™ photopolymer to meet the demanding requirements for holographic storage.
Aprilis: A spin-off from Polaroid, Aprilis was another company actively involved in holographic memory development, working alongside InPhase and Optware in the early 2000s.
Optware (Japan): Optware developed a format called Holographic Versatile Disc (HVD), which had a potential capacity of 3.9 TB.
All of the above was stolen from a Google AI search
Microsoft is working on using glass as a long term storage solution, that doesn’t degrade ever. Called Project Silica
I have a few thousand relays waiting for the day that I turn them into a CPU. This is great inspiration!
I think you only need about 2000 to make an i4004. But prepare to get a beefy power supply!
one can get realys that the current of the coils is quite small, so yea ok beefy compared to TTL but still well within reason to plug it into a wall outlet… its not the 1960’s anymore switch mode power supplies can provide surprising amounts of current off 110 power supplies
how many amps can a generic ATX power supply on its 12v rail? acc to the specs a 145 watt rated unit following the OG rules is good for 10 amps, and a 450 is good for 30
(that alone makes them kind of shit for makeshift bench supplies_
I have a 200 amp 5V power supply that I scrounged for the purpose some time ago. It won’t be enough, but I think I’ll add some logic to cascade switching. We shall see. There’s a reason it’s a work in progress…
When he first demoed the clock audio signal and it was a tone turning off and on I was confused and assumed I didn’t understand something. Then later when he hooked up the relay and it wasn’t happy, then explained the 60 Hz AC, I realized that I was right to be confused. The glance at the Arduino code for the clock (which I’m not familiar with) didn’t make me think it was generating AC with a clock envelope.
I should say that in retrospect it makes sense because it is storage on an audio tape, so I’m not sure what I was expecting.