Oh, and nobody would be able to touch-type. And hacked-up 78rpm shellac disks might not compare well to conventional hard-drives. They might not be quite as reliable, though. If Sir Clive was in charge today, we’d have THz CPUs for pennies. Using some clever R register tricks I think. I’ve mentioned it before, but the Spectrum bit-banged EVERYTHING! The ZX81, it’s predecessor, even did the video signal partly in software. Shows the Sinclair approach of cheapness first, second, and last, vs the Americans who seemed to come from a mainframe / mini approach, shrinking it down as much they could but using the “official” ways of doing stuff. Since a CPU’s not doing much during loading, why not use it? They’re fast! And of course the whole circuit was just a few gates on the ULA and the passives I mentioned. All timing done by the CPU, and something much the same for loading. The Spectrum just ran a line from the CPU, via one of the Z80’s I/O port addresses, to a couple of passive components so change the level suitably. Compared to the Atari or Commodore that took half an hour for the same, using actual chips to encode and decode. The Sinclair Spectrum had one of the fastest tape loaders for an 8-bit, 48K in about 3 1/2 minutes, work that out. 8-track heads were usually stereo, so they could have doubled that with a bit more tweaking, only having to move the head to select between the 4 pairs. For the time it was released the graphics are amazing! The same page says it got 4800 baud out of 8-track tapes using 1 program per track, so presumably that’s 4800 baud just using 1 track. If you look at the Compucolor page a bit closer, it says the floppy drive add-on sold 25 units, not the computer. It hardly seems sane to remember CD players being treated with awe at how sophisticated and expensive they were! It was about 1989 or so, so plenty of people did. A really cheap package, again, a clever way of doing it. The CD was a dozen or so of their “greatest hits”. ![]() The existing Spectrum’s tape port contained capacitors that made it too slow to accept such fast signals, joystick ports were pretty much direct I/O connections to the CPU, so why not? The CD just contained very fast audio, since you can get up to 22KHz on one. A wire from the headphone port of a normal audio CD player, with a simple level-shifter going into the computer’s joystick port. Stereo came later in midi systems and cheap ghetto blasters.Ĭodemasters, for the ZX Spectrum, released a clever adapter for CD “ROM” use. No computers of the day bothered with using both stereo channels, but most cheap tape decks from the early 80s were mono anyway. Would be cool to use as many tracks of the 8 as you could, too. So that’s what I’d do if I had to implement audio tape storage. Easy enough to do in software, doesn’t take much hardware. Which I suppose is more or less Manchester. ![]() Mostly they used a certain-length pulse for 0, and another (half or double the length) for 1. Posted in Arduino Hacks, classic hacks Tagged 8-track, scsi Post navigation ![]() This is probably a problem with the 40-year-old 8-track tape he’s using, but as a proof of concept it’s not too bad. The read/write speed is terribly slow – from the video after the break, we’re assuming is running his tape drive right around 100 bits/second – much slower than actually typing in data. By encoding four bits on each track, he’s able to put an entire byte on two stereo tracks. On the computer side of things, is using a simple UNIX-style, pipe-based I/O. Data is encoded with DTMF with an FSK encoding, just like the proper cassette data tapes of the early days. Inside is an Arduino that controls the track select, tape insertion and end of tape signals. installed an 8-track drive inside an old external SCSI hard drive enclosure. It should be noted that nearly no one has heard about these two computers – the Compucolor sold about 25 units, for example – so we’ll just let that be a testament to the success of 8-track tape drives. The Compucolor 8001 had a dual external 8-track drive, and the Exidy Sorcerer had a tape drive built in to the ‘the keyboard is the computer’ form factor. This actually isn’t the first instance of using 8-tracks to store data on a computer. thought this was a gross oversight of late 1970s engineers, so he built a 8-track tape drive. Cassette tapes, mind you, not 8-track tapes. Before created the elegant Disk II interface for the Apple II, and before Commodore brute-forced the creation of the C64 5 1/4″ drive, just about every home computer used cassette tapes for storage.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |