Using a FSK modem as tape storage interface - Page 1
Forum section: electronics / projects

author: ChristofferB
author_rank: Frequent Contributor
timestamp: November 28, 2015, 08:05:03 pm
content: So once again, I'm back with something completely obsolete, but kinda interesting anyway.I was reading up on a FSK-modem on-a-chip (AM7910PC), and it really looks very simple to use. So would it be possible to connect the RX/TX line directly to speaker/mic lines on a cassette/reel tape deck, and store serial data that way?Could you use a old junk modem for this purpose? has it been done?-No, I understand this isn't a very efficient solution, but it's intriguing, isn't it??--Christoffer

author: nctnico
author_rank: Super Contributor
timestamp: November 28, 2015, 08:18:12 pm
content: This exactly how old home computers like Commodore 64, MSX, etc saved data onto audio tapes! This technology is from the beginning of computing.

author: ChristofferB
author_rank: Frequent Contributor
timestamp: November 28, 2015, 08:33:21 pm
content: Exactly! Now, since modem hardware uses the same-ish FSK ideas; could you use modem hardware for the same purpose?--Christoffer

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 28, 2015, 09:22:19 pm
content: You'll have to emulate the handshake signals, but it is possible.For a bit more fun on something just slightly more practical, figure out how to read and write digital data on VHS tapes. Hint: SDR would probably be the easiest way to do it.

author: ChristofferB
author_rank: Frequent Contributor
timestamp: November 28, 2015, 09:28:02 pm
content: Yeah, I was hoping to use /DTR and /RTS to make a send/receive switch.--Perhaps. A VHS tape can have up to 20 GB of storage space. Might be interesting.-Christoffer

author: timb
author_rank: Super Contributor
timestamp: November 28, 2015, 10:54:24 pm
content: Quote from: NiHaoMike on November 28, 2015, 09:22:19 pmBack in the early 2000's, when digital camcorders had FireWire ports, I used my camcorder and MiniDV cassettes for backups. There was some software that would record the data across FireWire to the tape. If you played the tape back on a TV, you would see snow and lines, which was the actual binary data.It was a super cheap way to get 20GB of backup space. I rotated tape sets and kept them offsite. Worked really well!This is nothing new, though. I know as early as 1971 they were storing digital data on U-matic cassettes.Sent from my Tablet

author: German_EE
author_rank: Super Contributor
timestamp: November 29, 2015, 09:14:06 am
content: Way back in the early 1980's I was one of the many who saved their precious data on cassette tapes, in my case it was a TRS-80 Model 1. Yes, you could use an FSK modem as a tape interface but some things just deserve to die.

author: matseng
author_rank: Frequent Contributor
timestamp: November 29, 2015, 09:29:27 am
content: Quote from: ChristofferB on November 28, 2015, 09:28:02 pmThe Russians used to store up to 2 GB on a VHS tape about 20 years ago.https://en.wikipedia.org/wiki/ArVid

author: ChristofferB
author_rank: Frequent Contributor
timestamp: November 29, 2015, 11:09:19 am
content: Quote from: German_EE on November 29, 2015, 09:14:06 amA lot of innovations that deserve to die doesn't, like what I just suggested, and a lot of innovations that deserve to live dies, like the punched tape, and diode matrix roms..If nothing else, it'll be interesting. And when you have a computer that ONLY talks serial, it might not be too stupid a solution