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Multiple Head Read Write and Head Select Circuit

IP.com Disclosure Number: IPCOM000082688D
Original Publication Date: 1975-Jan-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Keidl, SD: AUTHOR

Abstract

The Fig. 1 circuit provides an inexpensive means for multiplexing two or more recording heads (heads 0 and 1) for magnetic tape between one write drive circuit 14 and one read amplifier circuit 16. The tape with which the heads 0 and 1 are to be used has two tracks, one for each of the heads; and each head 0 and 1 includes one center-tapped coil 18. One gating and read/write select circuit 20 is used with the single write driver 14 and single read amplifier 16 and can provide the read and write functions for both heads 0 and 1, with a significant product savings.

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Multiple Head Read Write and Head Select Circuit

The Fig. 1 circuit provides an inexpensive means for multiplexing two or more recording heads (heads 0 and 1) for magnetic tape between one write drive circuit 14 and one read amplifier circuit 16. The tape with which the heads 0 and 1 are to be used has two tracks, one for each of the heads; and each head 0 and 1 includes one center-tapped coil 18. One gating and read/write select circuit 20 is used with the single write driver 14 and single read amplifier 16 and can provide the read and write functions for both heads 0 and 1, with a significant product savings.

Four modes of operation are possible with the Fig. 1 circuit and the two recording heads 0 and 1. The modes are illustrated in the table below: MODE TXR TXR TXR TXR MODE OF NUMBER A1 B1 C1 C1 T1 T2 T3 T4 OPERATION 1 + + + - On Off Off On Writing with Head 0 + + - + On Off On Off Writing with Head 0 MODE TXR TXR TXR TXR MODE OF NUMBER A1 B1 C1 C1 T1 T2 T3 T4 OPERATION 2 - + + - Off On Off On Writing with Head 1 - + - + Off On On Off Writing with Head 1 3 + - + + On Off Off Off Read with Head 1 MODE TXR TXR TXR TXR MODE OF NUMBER A1 B1 C1 C1 T1 T2 T3 T4 OPERATION 4 - - + + Off On Off Off Read with Head 0.

As an example of operation, assume a change is made from mode 3 to mode
1. Transistor T1 turns on reverse biasing diodes D11, D17 and D14, degating head 0 from the read amplifier 16. Turning T1 on also forward biases diode D4 or D6 (D4 if T4 is on and D6 if...