NEC μCOM-4
Developer	NEC
Manufacturer	NEC
Production	October, 1977
Architecture	4-bit
Technology	nMOC "nMOC" is not in the list (BiCMOS, CMOS, Static CMOS, Dynamic CMOS, nMOS, pMOS, Bipolar, ECL, Schottky TTL, Schottky transistor, ...) of allowed values for the "technology" property.
Clock	150 kHz-440 kHz
Package	DIP28, DIP42

The μCOM-4 line is a family of 4-bit microcontrollers developed by NEC in the late 1970s. This family was designed to be low-cost, mass-produced, microcontrollers for ECRs, industrial controllers, appliance controllers, games, toys, scientific calculators, and other consumer electronics. The μCOM-4 line is based on the μPD751, the first Japanese single-chip microprocessor.

Introduction Date

1977				1980
Q1	Q2	Q3	Q4	Q1	Q2	Q3	Q4
μCOM-42	μCOM-43	μCOM-44	μCOM-45			μCOM-75

Members

Product	Part Number	ROM	RAM	I/O	Interrupts	Instructions	Pins
μCOM-42	μPD548	1920x10 bits	96x4 bits	35	2	72	42
μCOM-43	μPD546	2000x8 bits	96x4 bits	35	1	80	42
μCOM-44	μPD547	1000x8 bits	64x4 bits	35	1	58	42
μCOM-45	μPD550	640x8 bits	32x4 bits	21	1	58	28
μCOM-42 Evachip	μPD555	external	96x4 bits	36	2	72	64
μCOM-43 Evachip	μPD556	external	96x4 bits	36	1	80	64

Design

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Instruction set

Main article: μCOM-4 ISA

The family was originally split into two sets of ISAs. The μCOM-42 had an instruction set specifically designed to facilitate its use in Electronic Cash Register (ECR) and Scale products. The μCOM-43/4/5 were designed to be general purpose microcontrollers.

See also

• μCOM-8

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