System Integration and Testing with Microprocessors-- I. Hardware Aspects

In the development of a microprocessor-based system, component and system checkout become a real problem. The microprocessor might be in one integrated circuit package while the random access and read-only memories occupy several different circuit packages. The data bits encoded into processor instructions, the data stored in random access memories, and the data from input/output devices all time share the same hardware circuitry. Under these conditions it is nearly impossible to locate a fault or series of faults using conventional engineering aides, such as oscilloscopes, meters, digital probes, etc. Our solution to the hardware checking out problem is to use a minicomputer for most of the checking out chores. From the hardware point of view it is a great advantage to start with a known proven hardware component such as a well-built minicomputer should be. The hardware system integration between the minicomputer and the microprocessor can be made on a variety of system levels.