OPD Mini Processor

The OPD Mini Processor was an IBM single-chip FET microprocessor designed by Richard Vrba and used in the OS/6 word processors during the 1970s. It had a 16-bit little-endian instruction set built on an 8-bit internal architecture. Sixteen general purpose registers, implemented as a 32-byte window in memory that operated as a stack, could be used as instruction operands or for indirect references to operands in memory.