IBM 7330
The IBM 7330 magnetic tape unit was IBM's inexpensive magnetic tape - mass storage unit of the 1960s and belongs to the family of IBM 7-track systems. It was often used on the IBM 1400 and IBM 7040/7044 computers. The 7330 used ½ "(= 12.7 mm) magnetic tape up to 2400 feet (730 m) in length on rolls of 10½ " (= 26.7 cm) in diameter.
Data format
The head records seven parallel tracks on the tape, six for data and one parity bit . Tapes in BCD format were recorded with even parity, binary recordings use odd parity. (709 Manual p.20) When switching tape Aluminum strips were glued several feet before the band ends, to have physical start and end markers on the tape. A gap of ¾ inch was left between the data blocks (records) in order to resume recording and playback at this point . With a data density of 200 CPI, a 2,400-foot-long tape could store as much as 50,000 punch cards (over 4 million six-bit data words , or 3 Mbytes ).
The 7330 operated at a low tape speed of 36 IPS and supported two data densities of 200 and 556 characters per inch (CPI). The devices of the IBM 729 series ran belt speeds from 75 IPS.
literature
- Franz Haurenherm: The IBM 1401 magnetic tape system . In: From the Hollerith machine to the computer. IBM data processing in administration . Diplomica-Verlag, Hamburg 2011, ISBN 978-3-8428-6889-2 , p. 69 f . ( books.google.de ).
Web links
- Magnetic Tape Equipment manuals. Bitsavers.org (manuals as PDF files)