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Error-correcting codes in old tape-based formats

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First post, by Snover

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Hi everyone!

Google is failing me, so I figured I would ask here to learn if anyone has information about any error-correcting methods that were used by old compact cassette-based tape drives on systems like the ZX Spectrum +2 and the Commodore 64.

This really is totally unimportant, but someone brought up signal degradation on magnetic tape and I wanted to know what sort of coding these machines used to ensure data integrity. (From what I understand they didn’t do a particularly good job. 😉)

Thanks 😀

Yes, it’s my fault.

Reply 1 of 4, by rumbadumba

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http://www.cepece.info/amstrad/docs/manual/s968se08.pdf

contains info on cassette formats for the amstrad cpc computers, which were from the same time as the ones you mention.

For the zx81 the following indicates there was no error-correction or synchronisation:

http://www.michaelminn.com/linux/mmzx81/

Reply 4 of 4, by Sune Salminen

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I don't know if this is true or not but someone told me once that the reason why the C64 was so slow to load from tape (disk as well? can't remember) was that it loaded everything twice, with the second pass being for verification.

The 'turbo loaders' (as we used to call them back in DK) like Turbo Tape 64 and ABC Turbo that everyone used for their pirated games did away with that and obviously employed some other tricks as well.

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