PC-UX was a NEC port of UNIX System III

UNIX System III

UNIX System III was a version of the Unix operating system released by AT&T's Unix Support Group . It was first released outside of Bell Labs in 1982. UNIX System III was a mix of various AT&T Unixes: PWB/UNIX 2.0, CB UNIX 3.0, UNIX/TS 3.0.1 and UNIX/32V...

 for their APC III

APC III

The APC III was released by NEC in 1983. The APC III was based upon the Intel 8086 processor, with superior specifications to the IBM PC....

 and PC-9801

PC-9801

The NEC PC-9801, part of the PC-98 series, is a Japanese 16-bit microcomputer manufactured by NEC.- History :It first appeared in 1982, and employed an 8086 CPU. It ran at a clock speed of 5 MHz, with two µPD7220 display controllers , and shipped with 128 KB of RAM, expandable to 640 KB...

 personal computer. It had extensive graphics capability. PC-UX and MS-DOS

MS-DOS

MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...

 could reside on the same hard drive. It also had file transfer utilities that allowed files between PC-UX and MS-DOS. There was the PC-UX Softcard which allowed extremely high performance, reliability and memory utilization.