Group Code Recording

storage (GCR) A recording method used for 6250 BPI magnetictapes.

GCR typically uses a group of five bits of code to represent

four bits of data, where 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 Machines diskette

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. Also used on Amiga

internal and external drives.

Compare NRZI, PE.

(1997-08-29)