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Checking Automatic Threading of Magnetic Tape

IP.com Disclosure Number: IPCOM000073650D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Keffeler, JR: AUTHOR

Abstract

It is desired to automatically generate a sense byte indicating the extent of successful automatic threading in a magnetic tape unit. In most automatic threading operations of magnetic tape units, a series of major events comprise a complete load operation. These events are used as check points to aid in diagnostics. Upon the occurrence of each event, a binary 1 is inserted into a sense byte indicating the progress of the automatic threading. Upon a failure of the automatic threading, no more 1's are added to the sense byte.

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Checking Automatic Threading of Magnetic Tape

It is desired to automatically generate a sense byte indicating the extent of successful automatic threading in a magnetic tape unit. In most automatic threading operations of magnetic tape units, a series of major events comprise a complete load operation. These events are used as check points to aid in diagnostics. Upon the occurrence of each event, a binary 1 is inserted into a sense byte indicating the progress of the automatic threading. Upon a failure of the automatic threading, no more 1's are added to the sense byte.

An example of a sequence of major events with corresponding bit positions in the sense byte are tabulated: Sense byte Bit Event

0 Tape has passed head

1 Tape on machine reel

2 Four turns of tape on machine reel

3 Tape begins to enter vacuum storage

bins/columns

4 Tape is in storage bins/columns

5 backward to load point

6 Tape at load point

7 Ready.

For controlling purposes, such a sense byte is generated only after the CPU has issued a diagnostic load command, which also resets the sense byte to 0's. Sampling can be on a millisecond basis. The CPU diagnostic program having performance information stored therein reads the sense byte each time a major event should have occurred.

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