Using audio cassette tapes as a file storage media

TheBoyConor · 03-07-2019 12:35pm #1

I remember the days when my friend had a Commodore 64 that had a tape deck type device that served as the main external storage. Games and other apps came on compact cassette tapes and had to be ran through to load the data to the memory.

This is an interesting experiment I came across recently which I'd like to try out at home on my retro style build.....
https://www.instructables.com/id/Storing-files-on-an-audio-cassette/

I have already encoded a few image and pdf files to the audio wav filetype. I have a tape recorder at home that I can rig up to see can I write and then read and decode the data to recreate the original file.

I love this. Real low level computing, handling the raw data. Really cool.
Has anyone every experimented with similar?

Metric Tensor · 06-07-2019 12:40am

Haven't done anything like this myself but interested to read about it!

Lemming · 06-07-2019 12:59am

TheBoyConor wrote: »

I remember the days when my friend had a Commodore 64 that had a tape deck type device that served as the main external storage. Games and other apps came on compact cassette tapes and had to be ran through to load the data to the memory.

Selective memory is selective. I too remember the days of the C64 given that i still own one; there is a reason (or several) why tape was abandoned as a storage medium, not least because tapes are exceedingly susceptible to magnetic damage and diabolically slow to load.

As a "because I can" experiment, that article was a curious read, but that's about it given I had my fill of cassette data loading from the 1980s and early 1990s

beauf · 06-07-2019 1:21am

Lemming wrote: »

... I had my fill of cassette data loading from the 1980s and early 1990s

Same here. Used a VHS at one point for data.

Hurrache · 06-07-2019 1:31am

Yeah, may seem cool from a retro point of view but anyone having lived through that period would look upon it with anger.

Many a brother/sister received dead arms and legs for having the temerity for even breathing in the vicinity of a particularly dodgy tape which decided to stop loading after 20 minutes as they inevitably got the blame for it.

ED E · 20-07-2019 10:32am

Get some LTO8 tapes, same magnetic recording - much faster I/O.

smacl · 31-07-2019 9:13am

Hurrache wrote: »

Yeah, may seem cool from a retro point of view but anyone having lived through that period would look upon it with anger.

Many a brother/sister received dead arms and legs for having the temerity for even breathing in the vicinity of a particularly dodgy tape which decided to stop loading after 20 minutes as they inevitably got the blame for it.

Yep, ZX81 and Spectrum for me. Getting my first computer with a decent floppy drive was a monumental step forward, loading from cassettes was a hateful experience and not one to be repeated.

Capt'n Midnight · 07-06-2021 9:42pm

Tape is evil.

One of the nice things about the BBC micro was that you could rewind to try to reload a block. Other home PC's you had to start again and it could take a few minutes.

https://retrocomputing.stackexchange.com/questions/9260/how-much-data-could-a-home-computer-store-on-an-audio-cassette

Acorn adopted the 300-baud "Kansas City" or "CUTS" format for their early machines, and adapted this for higher performance with the BBC Micro. The basic baud rate is 1200, stored using ordinary TTY-modem style 1200/2400Hz FSK, but there is a lot of byte and block level framing which dilutes this in practice.

The standard block size is 256 bytes, plus 24-33 bytes of header and trailing CRC (depending on length of filename), each byte taking 11 bit times (8N2 serial framing). This totals 3080 bits per frame with a 1-character filename, taking 2.5667 seconds on the tape. Add 1.3 seconds of sync tone to allow stopping and restarting the tape motor between blocks.

A long file might thus approach 256 bytes per 3.8667 seconds throughput, or 66.2 bytes per second, in the standard format on the BBC Micro. It was possible to use longer blocks to speed up bulk loading directly into memory, but these files would then not work with the standard byte-by-byte file reading routines; probably some commercial games used this trick to speed up loading and reduce tape manufacturing costs.

At this speed a C30 tape (15 mins per side) could hold a little under 60KB per side.

there was a toy camera that recorded on audio tape , but to get the data transfer rate the used low res and the tape ran way way faster than normal

Tape Emulator
https://hackaday.com/tag/tape-emulator/

Capt'n Midnight · 07-06-2021 9:52pm

ED E wrote: »

Get some LTO8 tapes, same magnetic recording - much faster I/O.

Nope.

Don't get me stared on all the incompatibilities within LTO :mad:

There was always a new gotcha with any changes with tape backup systems.

Special prize for the new drive took the same tapes as the old one BUT wouldn't overwrite them because it didn't use as strong a magnetic field.

Using audio cassette tapes as a file storage media

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