TRACER CIRCUIT

PURPOSE:To utilize a storage for saving as a tracer, by turning on a flip-flop and inhibiting the resetting of a counter by BOP when the storage for saving is used as the tracer. CONSTITUTION:When the flip-flop FF is turned off to use an NAND gate G, the counter CNT is reset; the address of the storage SS is updated successively from an initial value during saving, and saved instructions are returned to the side of a main storage MS during retry operation. When the flip-flop FF is turned on to close the gate G, the resetting of the counter by BOP is inhibited and its counted value is increased up to its upper limit. Consequently, up-to- date data are stored in read order in the entire area of the storage SS.