Microprocessor and method for setting up its peripheral functions

Abstract

A single chip microprocessor 1 includes a CPU 2 and a sub-processor 5 for software implementation of peripheral functions of the microprocessor 1. Sub-processor 5 includes electrically writable internal storage devices microprogram memory unit 13 and sequence control memory unit 62 for storing the software. Peripheral functions are defined and/or modified by writing software into the memory units 13 and 62. Accordingly, the time it takes to define and/or modify the peripheral functions is the time it takes to program the memory units 13 and 62. The sub-processor 5 also includes an execution unit 16 for executing a plurality of tasks and an address control circuit 14 for providing addresses to the microprogram memory unit 13. Additionally, the microprogram memory unit 13 provides microinstructions to the execution unit 16. The sequence control memory unit 62 is part of the address control circuit 14 which also includes a plurality of address registers MAR0 to MAR11. The sequence control memory unit 62 is used for storing information regarding the order of selection of the multiple address registers MAR0 to MAR11. One of the address registers MAR0 to MAR11 is selected each time the sequence control memory unit 62 is read. A microaddress stored in the selected address register is then supplied to the microprogram memory unit 13.