A Short History of Microcomputers

The first commercial "home computer" was extremely primitive. The owner was required to enter programs into it by setting panel switches for each "character" ("byte" came later), toggle the "enter" switch, then dial in the next address, set its character switches (one for each bit), enter it, and so on. There was no way to save a program thus entered, so it would be lost when the machine was turned off.

When IBM decided to enter the microcomputer market, the microcomputer was already becoming fairly popular. Apple was the leader in the field, but there were quite a few other players including Tandy (Radio Shack). One of the hottest chips on the market was the Z80 by a company called Zylog. Apple was using Motorola chips. Tandy used chips from a variety of manufacturers depending upon the machine they were manufacturing.

Microsoft was a struggling software company in the Seattle area which made some of the best BASIC interpreters on the market. With their product, you could enter BASIC commands directly onto the computer and execute them immediately without a compiler.

IBM went with Intel's 8080 for their CPU chip which was actually substandard compared to the latest chips on the market. Microsoft purchased a small disk operating system called Seattle DOS, renamed it, and sold it to IBM. Since IBM was a hardware company that generally gave away software as part of a hardware sale, they allowed Microsoft to retain rights to the operating system.

So, two versions of the operating system ended up on the market, PCDOS and MSDOS.

The IBM PC hit the market in 1980.

Since IBM made the mistake of creating its machine out of standard parts, anyone could make a PC just like IBM's. The only thing missing was a BIOS, the micro coded program that provides the interface between the operating system and the actual hardware (chipset) in the computer. Third parties, such as Phoenix Technologies were only too happy to step to the plate. Then AMD and VIA Cyrix started cloning Intel's chips. So competition rapidly brought the price of PC's down.

This created an interesting situation. An office manager might have 100 people clamoring for a desktop computer. With his limited budget, he could purchase perhaps 30 superior Apple computers, but only from Apple since they had patent rights on their machine. Or he could purchase around 50 - 60 PC clones and satisfy more of his people.

As a result, the PC itself won the war, but IBM and Apple lost.

Xerox created a wonderful new windows operating system for its machine. It was a giant step forward for the time. Microsoft recognized it's value and copied (some say "stole") the technique and created the first Microsoft Windows operating system. It actually rode on top of DOS which had gone through a couple of generations by that time (the last DOS was version 6) and therefor suffered from the limitations of DOS including a memory addressing limit of 1000K. Since some areas were reserved for hardware input/output (I/O), only the lower 640K was available for RAM. To go beyond that barrier, extra memory had to be paged in and out of unused slots in the hardware I/O section in 4K pages.

Microsoft Windows has gone through several versions since then (1, 2, 3, 3.11, NT, 95, 98, ME, 2000, and XP). The most important change was to free it from DOS and make it into an operating system of its own, able to use 32 and 64-bit addressing and thus directly address more internal memory. Today's Windows along with improvements in hardware has created a computer that can run rings around the mainframes that IBM was selling when it created the first PC.

Other operating systems are available for the modern PC including Unix and Linux, both of which are preferred for local area network and Internet servers because they are more robust and have liberal policies that allow more clients to connect to the server for the basic purchase price.

Apple is still around with its Macintosh line, but most of the other desktop computers have gone the way of the dodo. However, Sun and others are still going strong in the so-called "mid-frame" market.

AMD, Apple, Apple Macintosh, IBM, IBM PC, Intel, Microsoft, Microsoft Windows, Phoenix Technologies, Tandy, Radio Shack, VIA Cyrix, Xerox, and Zylog are the registered trademarks of their respective companies