You've gotta love it when your birthday falls on the weekend - well, it did last Saturday for one of the most august of our members - the IBM Personal Computer.

The IBM PC, born 25 years ago, used a 4.77-MHz Intel 8088 processor and offered 16KB of memory. While it was preceded by the Radio Shack TRS-80s, the Commodore Pet and Apple II microcomputers, the IBM product created the market of today for PCs and servers.

The IBM PC was one of the first to use standard components, allowing many manufacturers to 'clone' them. One of the first clones was the Compaq luggable computer - called the Compaq Portable (I remember using one in the early 1980s to give sales demonstrations to customers). The Compaq Portable wasn't the most portable of machines, weighing in at 28 pounds.

IBM's machine was innovative in another area: it used an operating system - MS-DOS - from a start-up (we even had start-ups in those days) called Microsoft.

IBM renamed Microsoft's MS-DOS to PC-DOS and installed it with each PC that went out the door. When the PC was originally introduced in 1981, it didn't run much - WordStar for a word processor (ALT FS to save a file to disk, CTRL KD to exit) and VisiCalc or Lotus 1-2-3 spreadsheets - I still don't know the Excel macro commands that replaced Visicalc – to me it's @sum(C4..C12)*1.0825.

There was no multi-tasking with the IBM PC - the original PC had two 5.25-inch floppy drives and you could only run one program at the time. You had to boot from a floppy disk, take out the disk and then insert your word processing or spreadsheet disk.

Intel followed the introduction of the 8088 with the 80286, then the 80386 and 80486 processor. After that the company introduced the Pentium processor and the rest is history.

However, sales of IBM's PCs were eclipsed by Compaq in 1994. IBM ended its heritage with PCs by selling its PC division to Lenovo in 2004.

For more about IBM's PC, read this story "After 25 years, PC struggles with new challenges".

Happy birthday, IBM PC.