IBM Personal Computer
From Retrocomputing Wiki
| IBM Personal Computer | |
|---|---|
| Manufacturer | IBM |
| Type | Personal computer |
| Released | 12 August 1981 |
| Introductory price | US$1,565 (16 KB, no disk drives) |
| Discontinued | April 1987 |
| CPU | Intel 8088 at 4.77 MHz |
| Memory | 16 KB to 256 KB on the motherboard (640 KB with cards) |
| Storage | Cassette interface; one or two 5.25-inch floppy drives (160 KB) |
| Display | MDA or CGA card |
| Sound | PC speaker |
| Operating system | Cassette BASIC in ROM; PC DOS 1.0, CP/M-86, UCSD p-System |
The IBM Personal Computer, model number 5150 and usually called the IBM PC, is a personal computer announced by IBM on 12 August 1981. It was IBM's first successful microcomputer. Because IBM built it from standard parts and published its technical details, other companies were able to build compatible machines, and the "IBM compatible" PC went on to become the standard business computer and, in time, the most common personal computer of any kind.
Contents |
[edit] Development
By 1980 IBM was worried that it was missing out on the fast-growing personal computer market, where the Apple II and the TRS-80 were selling in large numbers. A small team at IBM's Entry Systems division in Boca Raton, Florida, first under William Lowe and then under Don Estridge, was given about a year to produce a machine. To work this quickly the team broke with IBM tradition and used parts from outside suppliers, including the Intel 8088 processor, and bought in software rather than writing it.
The operating system came from Microsoft, which had bought an existing system called 86-DOS from Seattle Computer Products and adapted it for IBM. IBM sold it as PC DOS, while Microsoft kept the right to license it to other manufacturers as MS-DOS.
[edit] Hardware
The Intel 8088 is a version of the 16-bit 8086 with an 8-bit external data bus, which allowed IBM to use cheaper 8-bit support chips. The base model had only 16 KB of RAM and a cassette port, but most were sold with 64 KB and one or two floppy disk drives. The motherboard has five expansion slots, and display adapters were sold as separate cards: the Monochrome Display Adapter for sharp text on IBM's green screen monitor, and the Color Graphics Adapter for colour graphics at up to 320 × 200 in four colours.
The keyboard was large and heavy, with a solid key feel that many users still prefer, although its unusual layout of the Shift and Return keys was criticised.
[edit] Clones
The only part of the PC that IBM did not publish openly was the BIOS ROM. In 1982 Compaq produced a compatible BIOS using engineers who had never seen IBM's code, and the Compaq Portable went on sale in 1983. Phoenix Technologies began licensing its own compatible BIOS to any manufacturer in 1984, and from then on dozens of companies built PC clones. By the late 1980s IBM's own share of the market it had created was falling steadily.
[edit] Successors
- IBM PC XT (1983): a 10 MB hard disk and eight expansion slots.
- IBM PCjr (1983): a cheaper home version that sold poorly.
- IBM PC AT (1984): the Intel 80286 processor and a 16-bit expansion bus.
- IBM Personal System/2 (1987): replaced the original PC range.
The 5150 itself was discontinued in April 1987 when the PS/2 was announced.
