(μPD500 series), NMOS devices (μPD1500 series, μCOM-43N ), and CMOS devices (μPD650 series, μCOM-43C ). 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 (28-pin or 42-pin). A ROM-less chip (μPD556) 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 (see below). μCOM-47 The μCOM-47 (μPD766) 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 (μPD7502 etc.) used CMOS. A ROM-less chip (μPD7500) 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 (μPD753) 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 (μPD8080A) 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: BCD arithmetic is supported for both addition and subtraction (Intel 8080: addition only). Similar to the N flag in the Zilog Z80, the μPD8080A has a SUB flag (bit 5 of the flag register) to indicate that a subtraction was performed. The instruction requires 4 clock cycles (Intel 8080: 5 clock cycles). 3-byte instructions are allowed in an interrupt acknowledge cycle, so a instruction to any memory address can be used (Intel 8080: only 1-byte instructions are allowed). Unfortunately, these improvements cause some programs written for the Intel 8080 not to run correctly. To overcome this problem, NEC introduced the μCOM-80F (μPD8080AF) 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 (μPD780) is an 8-bit microprocessor