It became IBM's standard tape drive for their early vacuum-tube era computer systems.
Later vacuum-tube machines and first-generation transistor computers used the IBM 729-series tape drive.
[1] The tape had seven parallel tracks – six for data and one to maintain parity.
Tapes with character data (BCD) were recorded in even parity.
Write protection is provided by a removable plastic ring in the back of the tape reel.