In 1971, Marcian E. “Ted” Hoff, an engineer at Intel Corporation was working on a chip for
a manufacturer of electronic calculators. He realized that it would be a better idea to develop
a general-purpose chip that could be programmed to interface with the keys and display of a
calculator, rather than to do yet another custom design. Thus, the microprocessor was born.
At the time, its primary application was as a controller for calculators, washing machines,
and the like. It took years for the computer industry to notice that a genuine central processing
unit was now available as a single chip.
Hobbyists were the first to catch on. In 1974 the first computer kit, the Altair 8800, was
available from MITS Electronics for about $350. The kit consisted of 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 $3,000 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 (see
Figure 8). In a spreadsheet, you enter financial data and their relationships into a grid of rows
and columns. 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 retrieve their data runs
from the computing center, snapped up VisiCalc and the computer that was needed to run it.
For them, the computer was a spreadsheet machine.
Figure 8 The Visicalc Spreadsheet Running on an Apple II
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 function-
