On 09/03/2018 07:58 AM, Al Kossow via cctalk wrote: > One thing I noticed that made me nervous is looking at the code there is no > checksum on either the sector address or data fields on the floppy. I made an > image of a floppy that I bulk-erased and initialized this morning, and all you > see are the sync bytes and data, no trailing data where a crc would be.
Looking at the ROM code disassembly, that certainly appears to be the case. Perhaps the attitude was "if you want to check your data, include a check in the data yourself". It wouldn't be the first time that this was done. Contrast with the Moto app note here for an 8" 3740-compatible setup using the 6852: http://www.bitsavers.org/components/motorola/6800/exorciser/AN764_A_Floppy_Disk_Controller_Using_the_MC6852_Oct76.pdf I recall that a friend had a KIM-1 with the KMISI expansion and a single SA400 floppy disk drive. I don't recall the details, but getting reliable operation was nearly impossible. --Chuck
