>... PICs were relatively late > comers, but General Instruments had them around by the early 1990s. Minor correction. GI had the PIC by 1976. It was a PMOS device. Microchip then got it and by the mid 80s had the CMOS 16C54/55/56/57 series available. I did some design work with the Microchip version around 1986 or 87. -Lyle KK7P