Hardware Reference
In-Depth Information
installed base for these applications—much to the dismay of companies who produce competing
versions. Microsoft also leverages its control of the OS to integrate its own networking software and
applications suites more seamlessly into the OS than others. That's why it dominates most of the PC
software universe—from OSs to networking software to utilities, from word processors to database
programs to spreadsheets.
In the early days of the PC, IBM hired Microsoft to provide most of the core software for the PC.
IBM developed the hardware, wrote the basic input/output system (BIOS), and hired Microsoft to
develop the disk operating system (DOS) as well as several other programs and utilities for the PC.
In what was later viewed as perhaps the most costly business mistake in history, IBM failed to secure
exclusive rights to the DOS it had contracted from Microsoft, either by purchasing it outright or by an
exclusive license agreement. Instead, IBM licensed it nonexclusively, which subsequently allowed
Microsoft to sell the same MS-DOS code it developed for IBM to any other company that was
interested. Early PC cloners such as Compaq eagerly licensed this OS code, and suddenly consumers
could purchase the same basic MS-DOS OS with several different company names on the box. In
retrospect, that single contractual error made Microsoft the dominant software company it is today
and subsequently caused IBM to lose control of the very PC standard it had created.
As a writer (of words, not software), I can appreciate what an incredible oversight this was. Imagine
that a book publisher comes up with a great idea for a popular book and then contracts with an author
to write it. Then, by virtue of a poorly written contract, the author discovers that he can legally sell
the same book (perhaps with a different title) to all the competitors of the original publisher. Of
course, no publisher I know would allow this to happen; yet that is exactly what IBM allowed
Microsoft to do back in 1981. By virtue of its deal with Microsoft, IBM lost control of the software it
commissioned for its new PC.
In the PC business, software enjoys copyright protection, whereas hardware can be protected only by
patents, which are much more difficult, time-consuming, and expensive to obtain. And in the case of
U.S. patents, they also expire 20 years after filing. According to the U.S. patent office, “any new and
useful process, machine, manufacture, or composition of matter, or any new and useful improvement
thereof” can be patented. This definition made it difficult to patent most aspects of the IBM PC
because it was designed using previously existing parts that anybody could purchase off the shelf. In
fact, most of the important parts for the original PC came from Intel, such as the 8088 processor, 8284
clock generator, 8253/54 timer, 8259 interrupt controller, 8237 DMA (direct memory access)
controller, 8255 peripheral interface, and 8288 bus controller. These chips made up the heart and
soul of the original PC motherboard.
Because the design of the original PC was not wholly patented and virtually all the parts were readily
available, almost anybody could duplicate the hardware of the IBM PC. All one had to do was
purchase the same chips from the same manufacturers and suppliers IBM used and design a new
motherboard with a similar circuit. IBM made it even easier by publishing complete schematic
diagrams of its motherboards and adapter cards in detailed and easily available technical reference
manuals. These manuals even included fully commented source code listings for the ROM BIOS
code. I have several of these early IBM manuals and still refer to them for specific component-level
PC design information. In fact, I highly recommend these original manuals to anybody who wants to
delve deeply into PC hardware design. Although they are long out of print, they do turn up in the used
book market and online auction sites such as eBay.
The difficult part of copying the IBM PC was the software, which is protected by copyright law. Both
 
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