IBM enters the fray, clone wars, when 640K is not enough

The personal computer market really started as something for hobbyists in the mid-1970s with the introduction of computers like the MITS Altair 8800. These early computers were in kit form and had to be assembled, putting them out of reach of mere mortals. That all changed in 1977 with the introduction of the Apple II, Commodore Pet, and TRS-80 Model I. All three of these computers were pre assembled and ready to use. This opened the door to a much wider audience and the popularity only grew from there. 1980 rolled around and there was a major player absent from this market, IBM. They had been keeping an eye on the personal computer industry and now wanted a piece of it. The biggest problem was that development cycles for any new IBM computer was on the order of 5 years. They designed almost everything in house from the ground up. They did not have that kind of time, so they did something totally out of character. They gave a group total control without having to get management approval. This group was based in Boca Raton, FL and used all off the shelf parts. They used a product from IBM called the System 23/Datamaster as a template to speed up production. They selected Microsoft to develop the Operating System, PC-DOS, and a set of development tools. The IBM PC model 5150 was ready in only 9 months being release on August 12, 1981.

IBM made the specifications to their new computer completely open to aid in getting 3rd parties to develop hardware and software for the new computer. It worked and sold like gangbusters. This unfortunately had a very undesirable side effect for IBM. Since the computer was built using off the shelf parts, anyone could be create exactly the same system and sell it under their own brand. The thing that kept this happening initially was the ROM BIOS code on the IBM PC motherboard. This was the intellectual property of IBM and could not be copied. Many found out the hard way getting taken to court over trying to do this. This was circumvented by companies like Compaq by doing a clean room design. They had a group of developers who had never seen the IBM source code design a workalike BIOS using only the specifications. This held up in court and now the floodgates were open for anyone using a workalike BIOS to sell their own IBM PC like system. The clone wars had begun. Companies like Phoenix Technologies created their own IBM PC compatible BIOS and then licensed it to computer makes to use in their clone systems. By the middle 1980s there were hundreds of IBM PC clone manufacturers. IBM would try to stuff the genie back in the bottle in 1987 with their PS/2 computer line. Long story short it did not work. This started a long slow decline for IBM in the PC business, finally getting out in 2005 selling that division to Lenovo.

The IBM PC was designed around the Intel 8088 CPU which could use up to 1MB of memory. That memory was divided into two areas in the IBM design. The first 640K was set aside for the Operating System and user programs. The last 384K was reserved for adapter cards and the computer ROM BIOS. Now 640K in 1981 was a lot of memory. A serious computer at that time had 64K, so having 10 times that would appear to have been enough, except that it quickly was not. The IBM PC was targeting at business, not home users. The first popular application for the IBM PC was Lotus 1-2-3, a spreadsheet program. People were now doing their financials on a microcomputer instead of a big mainframe. Those spreadsheets soon did not fit into a 640K memory space. Something had to be done. Lotus, Intel and Microsoft together came out with a memory expansion system called LIM EMS (Expanded Memory Specification) version 3.2. Their design took a 64K area of memory in the upper 384K space and with a combination of hardware and software created a window into a much larger memory space up to 8MB. A program written to take advantage of this would greatly increase its memory capacity. Lotus 1-2-3 users with an EMS board could now use much larger spreadsheets.

Today there are modern versions of these EMS boards that are sold for retro computer enthusiasts. I have a few in some of my PC builds. The one I use is a design from a company called Lo-Tech and the board is built by a company called TexElec, a Lo-Tech partner. In my next blog post I will cover one my computers in which I have an Lo-Tech EMS board installed. It is an interesting retro computer with a twist. It is retro, but brand new!

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