Read error correction in software

On 26 Jul 2007 at 6:40, dwight elvey wrote: Actually, on MFM, not even that good for single errors. Recall that the CRC on a 256-byte sector is the 257th and 258th byte of the sector. So, if an MFM error throws the data stream off, you don't even get a valid CRC to work with. And MFM data errors can result in data shifting and clock data "swapping". It might have been a whole 'nother story had the convention been that the CRC precedes the data. I've got some ideas about simulating a PLL-type clock in my routines developing bit cell "windows" instead of relying on the pulse-to- pulse spacing. The latter, while being very adaptable to ISV-type errors, is lousy for recovery of regular data errors. I'll keep the list posted, if anyone's interested. Cheers, Chuck