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# Synchronizing Randomly Occurring Signals

IP.com Disclosure Number: IPCOM000076128D
Original Publication Date: 1972-Jan-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 42K

IBM

Owen, CE: AUTHOR

## Abstract

Four-phase logic, in which modular circuit elements are activated cyclically and sequentially in four distinct phases A, B, C, and D, provides a useful approach to the construction of complex logical units using integrated circuits.

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Synchronizing Randomly Occurring Signals

Four-phase logic, in which modular circuit elements are activated cyclically and sequentially in four distinct phases A, B, C, and D, provides a useful approach to the construction of complex logical units using integrated circuits.

It may be convenient to communicate between units employing four-phase logic circuits when these units are some distance apart and use different clock sources. This can be done using the well-known start pulse technique, the allowable length of the burst of information being dependent on the stability of the oscillators employed. The figure shows a technique for correctly strobing the incoming information and getting it into a shift register operating on standard local phasing. In the figure, a box containing the letter A, B, C or D denotes a logic circuit which is arranged to strobe its input at the phase denoted by the letter, and to maintain its output for the two subsequent phases. Each stage of logic inverts its input signal, the figure indicating by a bar across two or more inputs that the circuit has an AND gate for those inputs. The absence of a bar indicates an OR input.

The normal interlogic unit four-phase logic signal has good information for only two consecutive phases. For transmission over a distance, a special output circuit is used which gives a signal that is good for three phase times. The `Start' pulse is merely an extra `one' inserted at the beginning of the message.

The in...