Silicon-on-sapphire (SOS) technology has been applied to the RCA COSMAC microprocessor to obtain a high-speed single-chip CPU. The chip has 4827 transistors and measures 5.3 mm square. The low device count is obtained through use of bit-serial arithmetic logic, a byte-serial incrementer, and a 5-transistor static storage cell. The low parasitic capacitance of the SOS structure permits a 40-MHz clock rate at 14 V.