NEC µPD768

Lore & Background

The μPD768 is the single-chip implementation of the μCOM-1600 series, following the earlier two-chip μCOM-16 (μPD755/μPD756) from 1974. It has 93 basic instructions, each consisting of 1 to 3 16-bit words. The memory space of 1 Mbyte (512K words) is byte-addressable, and the I/O address space is 2048 bytes. The processor includes 14 general-purpose registers.

Reader's Guide

The μPD768 features a 2-input vector interrupt, DMA control, refresh control for DRAM, and a master/slave mode to enable multiprocessor operation. As an original NEC design, it represents NEC's independent 16-bit development before the company shifted to Intel 8086/8088 compatible microprocessors in the μCOM-86 and μCOM-88 series, which were later superseded by the V series. The μCOM-1600 series did not see the same widespread adoption as the Intel-compatible μCOM-8 series, but it demonstrates NEC's capability in designing proprietary high-end processors.

Did You Know?

• The μPD768 is a single-chip 16-bit microprocessor announced in 1978.
• It has 93 basic instructions, each 1 to 3 16-bit words long.
• The processor supports a master/slave mode for multiprocessor operation.
• It includes DMA control and refresh control for DRAM.