NEC μCOM series


The NEC μCOM series is a series of microprocessors and microcontrollers manufactured by NEC in the 1970s and 1980s.

Overview

The μCOM series has its roots in one of the world's earliest microprocessor chipsets, the two-chip processor µPD707 / µPD708. Early in 1970, Coca Cola Japan set out to increase the efficiency of their sales outlets by introducing new POS terminals. Sharp was contracted to build these terminals, and NEC in turn to develop a chipset. The chipset development was complete in December 1971, at about the same time as other early microprocessors in the USA.
Since then, NEC has developed and manufactured various microprocessors and microcontrollers. General-purpose products among them were given series names starting with μCOM. The μCOM-4 series and μCOM-16 series were original developments, while the μCOM-8 series consisted mostly of Intel- and Zilog-compatible microprocessors.
The μCOM name disappeared when the V series and 78K series appeared in the 1980s, and the μCOM-87AD series, for example, came to be described simply as the 87AD series.

μCOM-4 series

μCOM-4

The μCOM-4 is NEC's original single-chip 4-bit microprocessor, announced in 1973. Unlike the Intel 4040, the μPD751 has separate data and address buses. A number of peripheral integrated circiuts were provided for the μPD751:
The μCOM-41 is a PMOS microprocessor in a 42-pin package. The following peripheral intergrated circuits were available:
The μCOM-42 is a 4-bit PMOS microcontroller in a 42-pin package. It has built-in ROM and RAM as well as keyboard, display, and printer controllers. The μPD548 requires a power supply of -10V and the outputs can switch up to -35V. A ROM-less chip in a 64-pin quad-in-line package was available for hardware and software development.

μCOM-43 through μCOM-46

The μCOM-43 series consists of more than 10 different 4-bit microcontrollers. Broadly speaking, there are PMOS devices, NMOS devices, and CMOS devices. The μCOM-43, μCOM-44, μCOM-45, and μCOM-46 have the same basic instruction set. They differ in the amount of ROM and RAM, the number of I/O pins, and the package. A ROM-less chip in a 64-pin quad-in-line package was available for hardware and software development. Beginning in 1980, they there were gradually replaced by the μCOM-75 series.

μCOM-47

The μCOM-47 is a 4-bit NMOS microcontroller in a 64-pin package. It has built-in ROM and RAM as well as keyboard, display, and printer controllers.

μCOM-75

The μCOM-75 series consists of 4-bit microcontrollers. Only the first device in the series, the μPD7520, was still developed in PMOS technology. All subsequent microcontrollers in the series used CMOS. A ROM-less chip in a 64-pin quad-in-line package was available for hardware and software development. By 1982 the μCOM-75 series was referred to as the μPD7500 series and later replaced by the 75X and 75XL series.

μCOM-8 series

μCOM-8

The μCOM-8 is an 8-bit microprocessor that is software-compatible with the Intel 8080, but differs in its 42-pin package and its completely different pin-out. There are minor software differences as well, e.g. the setting of flags for the SUB instruction.

μCOM-80

The μCOM-80 is an 8-bit microprocessor that is pin-compatible with the Intel 8080 and software-compatible with the μCOM-8. That is, the μPD8080A has some improvements compared to the Intel 8080:
Unfortunately, these improvements cause some programs written for the Intel 8080 not to run correctly. To overcome this problem, NEC introduced the μCOM-80F which is completely compatible with the Intel 8080 in all details. The 1979 catalog no longer listed the improved μPD8080A. With the TK-80, NEC offered a development board for μCOM-80, which due to its low price became popular with hobbyists.

μCOM-82

The μCOM-82 is an 8-bit microprocessor compatible with the Zilog Z80. The μPD780C corresponds to the original Z80 while the μPD780C-1 corresponds to the Z80A. The µPD780C-1 was used in Sinclair's ZX80, ZX81 and early versions of the ZX Spectrum, in several MSX computers, in musical synthesizers such as Oberheim OB-8, and in Sega's SG-1000 game console.
A CMOS version followed later.

μCOM-84

The µCOM-84 is compatible with Intel's 8-bit microcontroller 8048. CMOS microcontrollers up to μPD80C50 followed, but an Intel 8051 compatible product, which is the 8-bit industry standard, was never offered.

μCOM-85

The µCOM-85 is an Intel 8085 compatible 8-bit microprocessor.

μCOM-86, μCOM-88

The µCOM-86 and µCOM-88 are Intel 8086 and Intel 8088 compatible 16-bit microprocessors. They were superseded by the V series.

μCOM-87, μCOM-87AD

The µCOM-87 and µCOM-87AD are NEC original 8-bit microcontrollers. The μCOM-87AD adds an A/D converter to the μCOM-87. The register configuration consists of two sets of 8 registers each. The V register is a vector register that stores the upper 8 bits of the address of the working memory area, and the short address space which is fixed in the current 78K series can be freely arranged. The μPD7805 and μPD7806 have only one set of 7 registers. In the µPD7807 and later, the ALU is expanded to 16 bit and an EA register is added for 16-bit operation.
The series came in 64-pin quad in-line package. This series was superseded by the 78K series.

μCOM-16 series

μCOM-16

The μCOM-16 is a NEC original 16-bit microprocessor, implemented in two chips, the μPD755 and μPD756, in 1974.

μCOM-1600

The μCOM-1600 is a NEC original single-chip 16-bit microprocessor that was announced in 1978.
The processor has 93 basic instructions, consisting of 1 to 3 16-bit words. The memory space of 1 Mbyte is byte-addressable. The I/O address space is 2048 bytes. There are 14 general-purpose registers. The processor has a 2-input vector interrupt, DMA control, refresh control for DRAM, and a master/slave mode to enable multiprocessor operation.