Sanyo MBC-550 series

The MBC-550 series, also known as the MBC-550/555, is a series of personal computers sold by Sanyo. It was unveiled at the COMDEX/Spring '83 in April 1983 and first released to market in March 1984. All models in the MBC-550 series featured pizza-box-style cases and Intel 8088 microprocessors and run versions of MS-DOS. On its release in 1984, the MBC-550 was the least expensive IBM PC compatible released to date, at a price of $US$995 1984. The MBC-550 series followed Sanyo's MBC-1000 line of CP/M computers.

Specifications
The MBC-550 has much better video display possibilities than the CGA card (8 colors at 640x200 resolution, vs CGA's 4 colors at 320x200 or 2 colors at 640x200). Still, it is not completely compatible with the IBM PC.

The computer lacks a standard BIOS, having only a minimal bootloader in ROM that accesses hardware directly to load a RAM-based BIOS. The diskette format (FM rather than MFM) used is not completely compatible with the IBM PC, but special software on an original PC or PC/XT (but not PC/AT) can read and write the diskettes, and software expecting a standard 18.2 Hz clock interrupt has to be rewritten.

The MBC-550 was also the computer for NRI training. Starting by building the computer, the NRI promised you would be "qualified to service and repair virtually every major brand of computer". NRI was advertised in Popular Mechanics and Popular Science throughout 1985.

The MBC-550 is less PC compatible than the IBM PCjr. Its inability to use much PC software was a significant disadvantage; InfoWorld reported in August 1985 that Sanyo "has initiated a campaign to sell off" MBC-550 inventory. The company's newer computers were, an executive claimed, 99% PC compatible.

Early MBC-500 machines used true Intel 8088 microprocessors. In late March 1984, Sanyo reached an agreement with Intel to manufacture the 8088 in Japan as a second source, prompted by a widespread chip shortage at the time. As part of the agreement with Intel, Sanyo was not to sell their 8088 chips except as part of their Sanyo MBC-550 series computers.

Dedicated magazine
Soft Sector was a magazine for people who owned Sanyo MBC-550 and 555 DOS computers. (But much of the content equally applied to most IBM clones at the time.) A typical issue includes news, reviews, how-to's, technical advice and education, tips and tricks, as well as BASIC language programs that one could type in and adapt to suit one's needs.

Models

 * MBC-550 – 1 × 5.25-inch disk drive (160 KB)
 * MBC-555 – 2 × 5.25-inch disk drives (160 KB)
 * MBC-550-2 – 1 × 5.25-inch disk drive (360 KB)
 * MBC-555-2 – 2 × 5.25-inch disk drives (360 KB)
 * MBC-555-3 – 2 × 5.25-inch disk drives (1.2 MB)