 Instead of reading bit-by-bit, one can also read many 1.25 KB stretches and then assemble them together in a way akin to shotgun sequencing, an approach necessary for using slow connections on the Commodore 1541.Rapidlok was a copy protection scheme used widely by many companies and all versions of it never were successfully copied.They used a $00 value in between sectors which caused copiers to become "flaky" as it was an illegal GCR value.