16-bit CRC
28-Jan-92 00:03:22
Sb: #19395-16-bit CRC
Fm: Vic Wagner 76046,3004
To: Michael A McCormick 76046,1057
Mike,
One of the big difficulties with CRC is that you sorta have to
understand which 'order' the bits are gonna be 'sent' in. CRC was designed
for SERIAL error checking, and back in the dark ages (when dinosaurs roamed
the earth) bits were sent to the serial port (still are) least significant
bit 1st…so the CRC calcs tended to RIGHT shifts. Then along came IBM
(you gotta remember they're in business to sell HARDWARE, not make it easy
to program) and changed the order for writing to floppies…so CRC's tend
to get flipped end-for-end.