A moving nine-track tape passes across a stationary record head. The recorded tracks are parallel to the edge of the tape and run the full length of the tape.
Tape is read and written on a tape drive (or “deck”) which winds the tape from one reel to the other causing it to move past a read/write head. Early tape had seven parallel tracks of data along the length of the tape allowing six bit characters plus parity written across the tape. A typical recording density was 556 characters per inch. A tape has the following physical features:
Since tapes are often read one block at a time and tapes can not stop or start instantly, blocks are separated by interblock gaps, which contain no information and are long enough to permit stopping and starting.
The tape had reflective marks near its end which signaled beginning of tape (BOT) and end of tape (EOT) to the hardware.
