Well I've had some success with this checksum business. The data
checksum in the header is calculated as follows:
You have to do longword EOR's on the mfm encoded data block and then AND
the result with x55555555.
header data c/s = ( longword 1 EOR longword 2 EOR…longword 256 )
& x55555555
I am still playing with header checksum. It is supposed to be the
longword EOR's on the mfm encoded header data, but I haven't been able to
duplicate it yet. <Glenn