APC III

The APC III (Advanced Personal Computer) was released by NEC in 1983. An English-speaking market rebrand of the Japanese NEC PC-9801, the APC III was based upon the Intel 8086 processor, with superior specifications to the IBM PC. The computer was well designed from the ground up, and boasted exceptional reliability. It was advertised to business users.

Specification

Overview

The unit had an attractive look, and was physically smaller than an IBM-PC. The compact case included two 5¹⁄₄" half-height disks (two floppies or one floppy and one hard disk), and ample space for standard options (hard disk controller, additional video memory). Special options (including additional system memory) required using expansion slots, of which four were available.

Comparing the IBM PC to the APC III reveals how the two different architectures were derived. The IBM PC had been fast-tracked in an attempt to crack into the home computer market (reference Project Chess), resulting in a machine that actually looked cobbled together, especially internally. Conversely, the APC was truly engineered and showed NEC's considerable experience in the field of consumer electronics.

Expansion cards (PCBs) could be inserted without removal of the exterior case, as was required for the IBM PC. Even modern (IBM clone) designs still require removal of the case to add expansion cards.

The entire computer could be disassembled to functional blocks (e.g.: expansion card cage, power supply, disk drive cage) 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 easily further disassembled if required. Despite the easy disassembly, all components of the system were arranged and secured to reduce or eliminate mechanical stress on the electronics.

As with the IBM PC, the maximum usable memory was 640 KB (the address range of the Intel 8088 and 8086 is 1 MB). The APC came with 128 KB standard, as did the IBM PC.

Interfaces

RS-232 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. One significant reason behind IBM's separation of functions was reliability - faulty cards, particularly those at high risk of physical or electrical user damage (i.e. serial, parallel, and video) could be easily and individually replaced, at much lower cost than replacing or servicing the whole system board. In addition, this meant that existing, off-the-shelf hardware could be used, reducing costs and contributing to the fast-tracking of the project. Many years later, when manufacturers were producing reliable hardware, serial, parallel, then video and other interfaces migrated back to PC clone motherboards.

Display

Display resolution was exceptional for such a 'low' price computer. Maximum display capabilities were a text mode of 80×25 characters (with four planes) and/or graphics at 640×400 pixels (with two planes).^[1] 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 (taking the graphics mode from monochrome to either eight colours or eight shades of grey). The computer was capable of running monochrome (or grey) through an NTSC TV monitor, although this was not recommended (text reduced to 40×20, graphics to 640×200). Monochrome (usually green) or colour screens were usually included in the price. The colour screen was exceptionally clear, and gave the impression the resolution was higher than it actually was. The APC III's 'on-board' video controller meant that upgrades (other than internally mounted video memory) could not be achieved, and the display was stuck at 640×400×3.

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 (80 track, double density), although specifications imply the drives were only 360 KB^[2] (40 track, DD). 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-506 hard disks. This capacity could be increased to 20 MB (but no higher) after upgrading to MS-DOS 3.1.^[3]

Since it was deemed that no user would ever want to operate a computer without at least one floppy disk drive, the hard disk controller was only configured to operate a single internal hard disk. An external hard disk expansion port was available, but compatible external hard disks were never produced.

Operating systems

Shipped standard with MS-DOS 2.11, other operating systems were available, such as the Unix derivative, PC-UX. Later, MS DOS 3.1 was released for the APC.

Compatibility

The APC III was not compatible with the IBM-PC, either on a hardware level (although some parts were compatible), or a software level (although again, some software was compatible). At the time of introduction, NEC stood a high likelihood of 'winning the war for domination of the home PC market' against IBM. The 'fast-track' strategy that IBM had adopted to get their computer to market first paid off. NEC pursued a formal design process, but even with the efficiency of a company that produced a wealth of consumer products quickly, the launch of the IBM PC was a year ahead of the APC III.

Although technically superior to IBM PCs, and substantially more reliable than clones, it entered the market a little cheaper than a genuine IBM, but substantially more expensive than a PC clone.

The earlier penetration of the market saw PC clones adopt the IBM PC architecture. Both companies were eventually beaten by the rise of the PC clone. In the export markets, NEC fell into line with the 16-bit IBM-AT architecture (aiming again for reliability with the APC-IV), and did not pursue the APC-III architecture any further.

External links

• The APC at Old Computers Net (first APC, not APC III)
• NEC APC. Bryan Skinner checks out NEC's long overdue comeback in the big business micro field Personal Computer News, September 29 1983, pp. 34-41
• The APC-III at the On-line Computer Museum
• NEC APCIII; NEC's PC with style. Product review in Creative Computing, Volume 11 Number 02 (February 1985), pp. 60-64; article also available (minus photos) as a web page
• NEC APC III. MS-DOS Machine with a display that overcomes IBM PC incompatibility; review in InfoWorld, February 25, 1985, pp. 42-43
• The NEC APC III. A business computer with high-resolution color graphics Byte Magazine Volume 10 Number 03: Bargain Computing (March 1985), pp. 256-265
• IBM Compatibility for the NEC APC III. An operating-system patch and a few other alterations give the NEC APC III clone status., BYTE Vol 10-09: 10th Anniversary Issue, September 1985, pp. 171-179
• NEC APC III. Trappings of a Winner, Bits and Bytes (NZ), May 1985 pp. 13-16
• NEC APC IV review in PC Magazine, January 27, 1987, pp. 194-195

References