Abstract: In a data processing or transmission system which includes at least two synchronized clocks, for example--T-rings A and B which generate timing pulses Tai and Tbi for microinstruction execution, synchronism is checked by logic circuitry which receives pulses from the clocks. At least one of the pulses is delayed by one or more pulse period durations ti. The logic circuit output signal is used as an input to an indicator latch which is periodically set by an independent check oscillator or clock. In a preferred embodiment, the delays are introduced by master-slave flip-flops, which receive predetermined combinations of the T-signals and set by the independent check clock.Several delay latches and associated AND gates may be used for different logical combinations of delayed and undelayed T-signals. This scheme can easily be expanded to accommodate more than two synchronously operating clocks.

Abstract: In a micro-controlled data handling system the number of lines and pins required to transfer control signals from the microprogram controls to be integrated circuit modules controlled by such signals is conserved by using two bussing paths for distributing the control signals to the modules. A first path is dedicated exclusively to pre-decoded control signal functions and a second path is shared for transferring both data and control signal functions. Each controlled module contains an additional decoding circuit for combinationally decoding control signal functions received through both paths.