Printer hammer resetting control system

Abstract

A microprocessor provides to a main instruction source, A FIFO memory, various instructions (paper feed, hammer settings, . . . ) for a printer represented by instruction register thereof. For each instruction of the (A,C) type representing an operation code (C) for instance, a set command) for the hammer with address (A), address (A) is inputted into a secondary instruction source, a FIFO memory, simultaneously with a time information (Y) issued from a cyclic type binary counter. A so called mask bit (Z) which changes of value on every cycle, is also inputted, after complementation with time information (Y). When the contents (Y,Z) of counter and the contents (Y',Z) available from the output of source, are identical, comparator indicates to control unit that address (A') available from the output of source corresponds to the address of an hammer to be reset. Control unit adds code (C=RESET) and provides instruction (A', RESET) to register. Control unit is also provided with various means for controlling the status of instruction sources and manages the priorities when contradictory instruction are received. The system allows the reset commands to be removed from microprocessor and the input/output devices thereof, which saves machine time. In addition, the number of instructions to be stored into source is almost halved.