COMMAND CHECK SYSTEM

PURPOSE:To prevent the transmission of an erroneous command and to improve the reliability in the internal processing by counting the pulse of a pulse output program to check whether or not the counted value is identical to the value of a given command. CONSTITUTION:When a register 3 receives a command bus signal, a command processing program is read in the unit of small modules from an ROM5, transferred to a microprocessor 4, executed and a check pulse is generated. When the processing is advanced normally up to the last module, a decoder 17 sets an output 18 by an overflow output of a pulse counter 15. A write signal 19 is generated from the processor 4 by executing a program of a write signal generating module succeedingly and the signal is outputted to an AND gate via an output port 20. This write signal 19 and a signal 18 are ANDed and a normal low-order device write signal 13 is generated.