(GCR) A recording method used for 6250 BPI {magnetic tapes}. GCR typically uses a group of five bits of code to represent four bits of data. The encoding ensures no more than two or three zeros occur in a row, and no more than eight or so ones occur in a row, where zeros represent an absense of magnetic change. GCR is also used on Commodore Business Machinesdiskette drives the 4040, 8050, 154x, 157x and 158x series of 5.25" and 3.5" low and high density diskette drives used with 8-bit home computers circa 1977 to 1992. It was also supported on Amiga internal and external drives but only used for reading non-Amiga disks. Compare NRZI, PE. (2004-06-01)
