IBM 7330
Encyclopedia
The IBM 7330 Magnetic Tape Unit was IBM's low cost tape
mass storage system through the 1960s. Part of the IBM 7 track
family of tape units, it was used mostly on 1400
series computers. The 7330 used 1/2 inch (12.7 mm) magnetic tape
up to 2400 feet (730 m) long wound on reels up to 10½ inch (267 mm) diameter.
, six for data and one to maintain parity
. Tapes with character data (BCD) were recorded in even parity. Binary tapes used odd parity. (709 manual p. 20) Aluminum strips were glued several feet from the ends of the tape to serve as logical beginning and end of tape markers. Write protection
was provided by a removable plastic ring in the back of the tape reel. A 3/4 inch gap between records allowed the mechanism time to stop the tape. At 200 characters per inch, a single 2400 foot tape could store the equivalent of some 50,000 punched card
s (about 4,000,000 six-bit bytes).
Low speed (36 in/s) dual density (200, 556).
Magnetic tape
Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...
mass storage system through the 1960s. Part of the IBM 7 track
IBM 7 Track
IBM's first magnetic tape data storage devices, introduced in 1952, use what is now generally known as 7 track tape. The magnetic tape is 1/2" wide and there are 6 data tracks plus 1 parity track for a total of 7 parallel tracks that span the length of the tape...
family of tape units, it was used mostly on 1400
IBM 1400 series
The IBM 1400 series were second generation mid-range business decimal computers that IBM sold in the early 1960s. They could be operated as an independent system, in conjunction with IBM punched card equipment, or as auxiliary equipment to other computer systems.1400-series machines stored...
series computers. The 7330 used 1/2 inch (12.7 mm) magnetic tape
Magnetic tape
Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...
up to 2400 feet (730 m) long wound on reels up to 10½ inch (267 mm) diameter.
Data format
The tape had seven parallel tracksIBM 7 Track
IBM's first magnetic tape data storage devices, introduced in 1952, use what is now generally known as 7 track tape. The magnetic tape is 1/2" wide and there are 6 data tracks plus 1 parity track for a total of 7 parallel tracks that span the length of the tape...
, six for data and one to maintain parity
Parity bit
A parity bit is a bit that is added to ensure that the number of bits with the value one in a set of bits is even or odd. Parity bits are used as the simplest form of error detecting code....
. Tapes with character data (BCD) were recorded in even parity. Binary tapes used odd parity. (709 manual p. 20) Aluminum strips were glued several feet from the ends of the tape to serve as logical beginning and end of tape markers. Write protection
Write protection
Write protection is any physical mechanism that prevents modification or erasure of valuable data on a device. Most commercial software, audio and video is sold pre-protected.-Examples:...
was provided by a removable plastic ring in the back of the tape reel. A 3/4 inch gap between records allowed the mechanism time to stop the tape. At 200 characters per inch, a single 2400 foot tape could store the equivalent of some 50,000 punched card
Punched card
A punched card, punch card, IBM card, or Hollerith card is a piece of stiff paper that contains digital information represented by the presence or absence of holes in predefined positions...
s (about 4,000,000 six-bit bytes).
Low speed (36 in/s) dual density (200, 556).
External links
- Bitsavers.org Magnetic Tape Equipment manuals (PDF files)