The IBM System/360, announced in 1964, introduced what is now generally known as 9 track tape. The ½ inch (12.7 mm) wide magnetic tape media and reels are the same size as the earlier IBM 7 track format it replaced, but the new format has eight data tracks and one parity track for a total of nine parallel tracks. Data is stored as 8-bit characters, spanning the full width of the tape (including the parity bit). Various recording methods have been employed during its lifetime as tape speed and data density increased, including PE (phase encoding), GCR (group coded recording) and NRZI (non-return-to-zero, inverted, sometimes pronounced "nur-zee"). Tapes come in various sizes up to in length.