Browse Prior Art Database

Device for Processing Magnetic Tape Data Without Idle Times

IP.com Disclosure Number: IPCOM000044147D
Original Publication Date: 1984-Nov-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Rausch, F: AUTHOR

Abstract

When magnetic tape reels or cartridges are used as storage media, about 1 to 5 msec. pass between the tape read instruction and the receipt of the data of a tape set. Although this time may be filled with other operations or the buffering of another tape set, such an approach is not used for small systems with, for example, only one application and a small work storage, so that unreduced idle times are incurred. With the device described below, the data are available upon request: Two magnetic heads C and D are arranged at a spacing G (gap length). When the magnetic tape is stopped, head C (as shown in the figure) is positioned at the end of tape set R2a, while head D is positioned at the start of tape set R2b. At that time, buffer E contains the data of tape set R2a read in response to the previous instruction.

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Device for Processing Magnetic Tape Data Without Idle Times

When magnetic tape reels or cartridges are used as storage media, about 1 to 5 msec. pass between the tape read instruction and the receipt of the data of a tape set. Although this time may be filled with other operations or the buffering of another tape set, such an approach is not used for small systems with, for example, only one application and a small work storage, so that unreduced idle times are incurred. With the device described below, the data are available upon request: Two magnetic heads C and D are arranged at a spacing G (gap length). When the magnetic tape is stopped, head C (as shown in the figure) is positioned at the end of tape set R2a, while head D is positioned at the start of tape set R2b. At that time, buffer E contains the data of tape set R2a read in response to the previous instruction. A new read instruction causes the tape to be started and the contents of buffer E to be transferred to main storage H. During this time, the magnetic tape reaches the speed necessary for reading R2b, and head C is positioned at the start of tape set R2b. Then, switch S switches from buffer E to head C. Head D also reads tape set R2b and detects the set end mark by means of detector F, subsequently reading tape set R3a into buffer E. Head C detects the end of tape set R2b by means of detector K, stopping the tape. In addition to the fact that the data are readily available, the time for reading a...