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the microprocessor, a circuit board, a very small amount of memory, toggle
switches, and a row of display lights. Purchasers had to solder and assemble it,
then program it in machine language through the toggle switches. It was not a
big hit.
The first big hit was the Apple II. It was a real computer with a keyboard, a
monitor, and a floppy disk drive. When it was first released, users had a $3000
machine that could play Space Invaders, run a primitive bookkeeping program,
or let users program it in BASIC. The original Apple II did not even support
lowercase letters, making it worthless for word processing. The breakthrough
came in 1979 with a new spreadsheet program, VisiCalc. In a spreadsheet, you
enter financial data and their relationships into a grid of rows and columns (see
The VisiCalc Spreadsheet Running on an Apple II). Then you modify some of
the data and watch in real time how the others change. For example, you can see
how changing the mix of widgets in a manufacturing plant might affect
estimated costs and profits. Middle managers in companies, who understood
computers and were fed up with having to wait for hours or days to get their data
runs back from the computing center, snapped up VisiCalc and the computer that
was needed to run it. For them, the computer was a spreadsheet machine.
The next big hit was the IBM Personal Computer, ever after known as the PC. It
was the first widely available personal computer that used Intel's 16-bit
processor, the 8086, whose successors are still being used in personal computers
today. The success of the PC was based not on any engineering breakthroughs
but on the fact that it was easy to clone. IBM published specifications for plug-in
cards, and it went one step further. It published the exact source code of the
so-called BIOS (Basic Input/Output System), which controls the keyboard,
monitor, ports, and disk drives and must be installed in ROM form in every PC.
This allowed third-party vendors of plug-in cards to ensure that the BIOS code,
and third-party extensions of it, interacted correctly with the equipment. Of
course, the code itself was the property of IBM and could not be copied legally.
Perhaps IBM did not foresee that functionally equivalent versions of the BIOS
nevertheless could be recreated by others. Compaq, one of the first clone
vendors, had fifteen engineers, who certified that they had never seen the
original IBM code, write a new version that conformed precisely to the IBM
specifications. Other companies did the same, and soon a variety of vendors
were selling computers that ran the same software as IBM's PC but distinguished
