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

Lines

μCOM-42

The μCOM-42 (also referred to as μPD548) was specifically marketed for electronic cash registers (ECRs), Point of Sale (POS), and electronic scale applications. The μCOM-42 chips were specifically designed for controlling 8x4 keyboards, 8-digit displays, and various ECR-type printers.

The single-chip had single-byte 72 instructions with a 10µsec instruction cycle. The chip included 1920x10-bit program memory, 96x4-bit data memory, 4-level stack, 2 interrupt request lines, and various I/O ports.

μCOM-43

The μCOM-43 (also referred to as μPD546) was marketed as a general-purpose microcontroller suited for a large array of low-cost consumer and industrial applications.

The single-chip had 80 general instructions with a 10µsec instruction cycle. The chip included 2000x8-bit program memory, 96x4-bit data memory, 3-level stack, various interrupt request lines and 35 I/O ports.

μCOM-44

The μCOM-44 (also referred to as μPD547) was marketed as a low cost general-purpose microcontroller suited specifically well for various controllers due to its large amount of I/O ports, similar to the μCOM-43.

The single-chip had a reduced 58 general instructions with a 10µsec instruction cycle. The chip included a reduced program memory of 1000x8-bit, reduced data memory of 64x4-bit, a single-level stack, but a large set of 35 I/O ports.

μCOM-45

The μCOM-45 (also referred to as μPD550) was the low-end, ultra low cost general-purpose microcontroller suitable for mass-produced extremely low cost consumer products.

Like the μCOM-44, the μCOM-45 had a reduced instruction set of 58 instructions with a 10µsec instruction cycle. The chip included a reduced program memory of 640x8-bit, reduced data memory of 32x4-bit, a single-level stack, and only 21 I/O ports.

μCOM-75

The μCOM-75 series were introduced in early 1980 made in CMOS technology and had comparable features to the previous μCOM-4 product line.

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