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The Atanasoff Berry Computer, or ABC,
was a remarkable innovation for a number of reasons. Characteristics
of modern computers trace their roots directly to the ABC, which
sits at the top of the family tree of computing.
Particular breakthroughs first found
in the ABC include:
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Electronic regenerative memory -
Today's RAM memory chips employ the same
concepts first employed by the ABC. While the computer is on,
the memory is refreshed. Atanasoff called this "jogging"
the memory. The use of the word "memory" itself in relation
to computers is also credited to Atanasoff.
Base 2, or binary, storage -
In other computing devices, it was customary
to use the base-10 system that humans use for working with numbers.
Using a base-2 system was ingenious because it took advantage
of the "on-off" nature of vacuum-tube electronics and
punched cards.
Boolean Logic -
Today, using the "ANDs" and "ORs"
of Boolean logic
for computing seems natural. In the 1930s, however, primitive mechanical
calculators were using decimal gears to manually crank out results.
By going with base-2 arithmetic, Atanasoff made use of Boolean logic
for computing possible.
Separation of memory and computing functions -
In essence, all of the primary components
found in today's computers -- CPU, storage devices, and memory
-- were present in the ABC for the first time. The add-subtract
circuits found in the ABC were modular and could be popped out
and replaced much in the same way a CPU chip can be today. The
memory storage in the ABC -- a total of 3.2 kilobits -- was completely
separate from the add-subtract units.
Global system clock-
Today's computers are often measured in
terms of their "gigahertz" clock speeds. That feature
of a system clock for the computer to time its operations was
first introduced in the ABC, allowing more reliable and repeatable
operations.
Parallel processing-
Some people think that parallel processing
-- the ability for a computer to do more than one thing at the
same time -- is a fairly recent idea. But the ABC was far ahead
of its time in this respect. It did 30 operations at once, using
a technology that today we call SIMD (pronounced "sim-dee"),
for Single-Instruction Multiple-Data parallel computing. Parallel
processing is now universal in the design of computers from PCs
to the largest mainframes.
Any one of these innovations would have been
remarkable for the late 1930s. Atanasoff's breakthrough in Rock Island
was to decide upon all four of these concepts in one evening - essentially
the conception of the modern family of computers that we enjoy today.
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