12-21-2021, 11:56 AM
The SuperCard Pro uses a hardware interrupt to start the capture and that comes from the index pulse. The index to index time and total number of bitcells comes from the drive. If you are seeing a shorter (or longer) duration from revolution to revolution then that would be the information that is provided by the drive itself. It could be that the drive is really slow at spinning up or takes some time to transition from a step to a read. Some really old 5.25" drives need a long delay after a step is issued before reading can occur.
The number of bitcells can vary quite a bit depending on the number of weakbits (invalid flux) and how invalid flux is handled by your particular model disk drive. What disk drive are you suing? Note that the number of bitcells can change from read to read of the same track because of invalid flux and how the disk drive handles it, so don't expect that value to be 100% consistent. Drive speed variations will change invalid flux values. Invalid flux can span anywhere from a single bitcell to multiple bitcells (thousands) depending on the flux.
The number of bitcells can vary quite a bit depending on the number of weakbits (invalid flux) and how invalid flux is handled by your particular model disk drive. What disk drive are you suing? Note that the number of bitcells can change from read to read of the same track because of invalid flux and how the disk drive handles it, so don't expect that value to be 100% consistent. Drive speed variations will change invalid flux values. Invalid flux can span anywhere from a single bitcell to multiple bitcells (thousands) depending on the flux.