MICROPROGRAMMED PROGRAMMABLE CONTROLLER

摘要

A programmable controller includes a processor formed around a pair of four-bit bipolar microprocessors. A control program formed by selected macroinstructions is stored in a random access memory and it is executed by sequentially mapping each macroinstruction operation codes into a corresponding microroutine which is stored in a read-only memory. Some macroinstructions include operand addresses of a line in an I/O image and data table portion of the random access memory and one macroinstruction (ADX) expands this operand address to enable the I/O image and data table to be expanded in size. A timer macroinstruction is executed in part by reading the state of a counter which is driven by a real time clock, and arithmetic functions are performed more effectively with the use of a decimal adjust accumulator.