Compute! magazine had really cool stuff (really nice monitor/debug program for instance) in hexdump format with checksum bytes on the end. They had a custom pr

Compute! magazine had really cool stuff (really nice monitor/debug program for instance) in hexdump format with checksum bytes on the end. They had a custom program that let you enter the hex, then calculated the checksum and compared it to the check digits entered. Prevented a LOT of typos :-)