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Compare Circuit Error Check

IP.com Disclosure Number: IPCOM000098781D
Original Publication Date: 1959-Dec-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Gerrand, F: AUTHOR

Abstract

The apparatus error checks the operation of circuitry used for comparing corresponding pairs of flip flops, such as 1 and 2 of drum compare registers A and B. Successive first and second pulses appear on conductor Pl to clear flip flop 11 and sample the matrix including gates 3-5 and 4-6 individual to the pair of register flip flops. If these flip flops both are in the 1 state, the first pulse passes through gates 3 and 5, but not gates 4 and 6. However, the flip flops are complemented by the passage of the first pulse through delay lines 7 and 8 to the complement inputs of those flip flops, so that both flip flops are placed in 0 state.

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Compare Circuit Error Check

The apparatus error checks the operation of circuitry used for comparing corresponding pairs of flip flops, such as 1 and 2 of drum compare registers A and B. Successive first and second pulses appear on conductor Pl to clear flip flop 11 and sample the matrix including gates 3-5 and 4-6 individual to the pair of register flip flops. If these flip flops both are in the 1 state, the first pulse passes through gates 3 and 5, but not gates 4 and 6. However, the flip flops are complemented by the passage of the first pulse through delay lines 7 and 8 to the complement inputs of those flip flops, so that both flip flops are placed in 0 state.

The second pulse then is blocked at gates 3 and 5. The absence of a pulse at the matrix output indicates a successful compare. Should either the first or second pulse get through to sample gate 12, a pulse on conductor P3 may get through to strobe gate 12 for an error indication. For a no compare situation, the aforementioned first pulse strobes either gates 3 and 5 or gates 4 and 6, complements flip flop 1 once and flip flop 2 twice in order to set up a compare condition between flip flops. The aforementioned second pulse should not get through. However, if it does, it strobes gate 12 for an error indication.

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