The birth of personal computers

The IBM Personal Computer arrived in 1981 and became the leading platform in the revolution that brought computing out of the glass house and into daily life.

When the IBM Personal Computer (IBM 5150) was introduced to the world 39 years ago, it was dramatically clear to most observers that IBM had done something very new and different.

Let’s take an in-depth review of the IBM PC, which brought a revolution in the technology.

What is PC?

A personal computer (PC) is a multi-purpose computer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end-user. The term “PC” has been traditionally used to describe an “IBM-compatible” personal computer in contradistinction to an Apple Macintosh computer.

History of PC

When the PC was introduced in 1981, it was originally designated as the IBM 5150, putting it in the “5100” series, though its architecture wasn’t directly descended from the IBM 5100.

The IBM PC was created in about a year by a team of 12 IBM engineers and designers under the direction of Don Estridge of the IBM Entry Systems Division in Florida.

The 12-member team decided to use the Intel 8088 (8/16 bit) processor in the PC. Then they asked Digital Research (DR) to create an operating system for their new computer, but as DR was not interested, they then asked a small company (known for its BASIC Programming Language, first used in Altair 8800) to write the operating system: Microsoft.

The original IBM PC wasn’t very powerful. The very first PC’s had only 16 KB RAM and no floppy disk units, they used cassettes to load and store programs. In fact, units could also be purchased from IBM with drives and more RAM.

After updating

The model 5150 was later updated in the same year [1981] in order to achieve stability. The system unit was a box with size 50.8 (W) x 40.6 (D) x 14 (H) cm, with a built-in 63.5W switching power supply unit.

It featured Intel 8008 CPU, working at speed 4.77 MHz, and an optional math co-coprocessor 8087. The RAM was 64 KB (the very first ones had only 16 KB), 256 KB max (then later 640 KB max).

The ROM was 64 KB, included built-in language IBM BASIC. The keyboard was a full stroke ‘clicky’ 83 keys with 10 function keys and numeric keypad.

The display was monochrome, working in text mode: (40 or 80 char x 25 lines) or 2 CGA graphic modes: (320 x 200 and 640 x 200). The sound was a tone generator with a built-in speaker.

The I/O ports were five internal 8 bit ISA slots, monitor, parallel (Centronics), cassette. The built-in media was one or two 160 KB 5.25” disk-drives. Three OS are provided—MS-DOS, CP/M-86, USCD Pascal.

Next PC models

IBM PC XT was launched in 1983 (first IBM PC to come with an internal hard drive as standard), and IBM AT was launched in 1984 (with the new Intel 80286 CPU).

IBM continued production of the original PC in various configurations, for several years. The model types were followed by an xx version number, i.e. 5150-xx, where the xx represented the included options (amount of RAM, single or dual floppy disk drive, etc.)

Success

IBM PC 5150 became actually a success due to the name and fame of IBM, high-quality construction (especially the keyboard and monitor), great expandability, and IBM’s decision to publish complete technical specs.

Time Magazine, for its famous “Man of the Year” edition for 1982, and put the personal computer on its January 3, 1983, cover as “Machine of the Year.”