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Program Loop Switch for Testing Purposes

IP.com Disclosure Number: IPCOM000094203D
Original Publication Date: 1966-Jul-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Koederitz, F: AUTHOR

Abstract

In electronic data processing systems the internal control of which is effected by microprograms stored in read-only stores, the operations of testing and servicing the systems are impeded. This is because a fixedly predetermined microprogram loop can be executed only in the order defined by the sequence stored in the read-only store.

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Program Loop Switch for Testing Purposes

In electronic data processing systems the internal control of which is effected by microprograms stored in read-only stores, the operations of testing and servicing the systems are impeded. This is because a fixedly predetermined microprogram loop can be executed only in the order defined by the sequence stored in the read-only store.

In diagnosing an error in the system, it is, however, of great advantage to cause only a definite number of micro-instructions to be executed continuously or to effect branching to a predetermined micro instruction by selective signals, e.
g., on a Read error. The procedure and arrangement associated with it are as follows.

The drawing shows the address bit board of the read-only store of an EDPM data processing system, by which access to the individual address bits 1...n is provided. By a connected, separate set of address switches s1, that address is set up at which branching is to be effected. Such is for testing purposes to any desired address that can be indicated by the address set up in the address switches contained in the system.

When the address set up by the address switches s1 is reached, a combination of Exclusive-Or's OE is caused to produce an output signal by which a latch D is set. The latter, in turn, prevents the sequence address from entering the address register of the read-only store. The output signal is also used for placing the address set up with the built-in address...