The APC III was released by NEC in 1984. An update on the NEC APC II, which replaced the original NEC APC from the early 1980s, all the NEC APC models utilized the Intel 8086 processor with a 16-bit memory bus, unlike the IBM-PC and clones, which relied on the 8-bit bus of the Intel 8088 processor. It was advertised to business users.
Specification
Overview
The unit was physically smaller than an IBM-PC. The compact case included two 5" half-height disks, and space for standard options. Special options required using expansion slots, of which four were available. C-bus expansion cards could be inserted without removal of the exterior case, as was required for the IBM PC. The entire computer could be disassembled to functional blocks with removal of a few easy access screws. Other components didn't even need a screwdriver, except for the outer case, by using robust plastic clips. The disk cage could be further disassembled if required. As with the IBM PC, the maximum usable memory was 640 KB. The APC came with 128 KB standard.
Interfaces
serial, 'Centronics' parallel and video interfaces were built onto the motherboard, whereas expansion cards were required for almost every function of an IBM PC except for the CPU, BIOS and built-in RAM.
Display
Maximum display capabilities were a text mode of 80×25 characters and/or graphics at 640×400 pixels. Either text, graphics, or graphics with text overlay were software selectable. The base one bit-per-pixel was easily upgradeable to three bits per pixel. The computer was capable of running monochrome through an NTSC TV monitor, although this was not recommended. Monochrome or color screens were usually included in the price. The APC III's 'on-board' video controller meant that upgrades could not be achieved, and the display was stuck at 640×400×3. The NEC APC series supported a proprietary NEC APC character set and user-definable fonts in text mode.
Expansion bus
The expansion bus supported 16-bit-wide data and 20-bit-wide address capability. The original IBM supported an 8-bit data bus with 20-bit address, which was later revised to 16 data bits and 24 address bits in the PC AT. The motherboard was designed to allow easy addition of an 8087 math co-processor.
Disk drives
Most Australian units were shipped with 720 KB floppy disk drives, although specifications imply the drives were only 360 KB. 360 KB disks were readable and writeable by 'double-stepping' the 720 KB drives. Users could also purchase a hard disk expansion option. This was initially limited to the 10 MB ST-506hard disks. This capacity could be increased to 20 MB after upgrading to MS-DOS 3.1. The hard disk controller was only configured to operate a single internal hard disk. An external hard diskexpansion port was available, but compatible external hard disks were never produced.
The APC III was not fully compatible with the IBM-PC, either on a hardware level, or a software level. The earlier penetration of the market saw PC clones adopt the IBM PC architecture. In the export markets, NEC fell into line with the 16-bit IBM-AT architecture and did not pursue the APC-III architecture any further.
