| I count
about nine “dominos” in this picture. Some are fours, some are twos,
although a few are not quite regulation. It would seem that this
microprocessor is playing its own games (I’m sure we all have felt that way
about our own computer at one time or another). While these perceived images
have nothing to do with the computer chip’s function, it is interesting to
find these allegories of the chip’s capabilities embedded in the chip’s
logic.
Of course these are not actually dominos; they are the connecting points
in a very complex grid of interconnections in the arithmetic and logic
section of a Motorola 6800 microprocessor. This interconnection scheme was
much more organized and well thought out than those found in many of the
other early microprocessors. When microprocessors were introduced, they were
referred to as “random logic” devices. While looking at the microprocessor’s
ivy-like traces wandering back and forth, you might believe you have
discovered the origin of this naming. However tempting, the name “stems”
from the fact that, even though the logic circuits in the microprocessor are
fixed in silicon, the microprocessor’s logic is reconfigurable through
programming and hence the randomness of the logic. As microprocessors have
become more complex, the need for structured logic design has become a
necessity for the designer’s productivity… and sanity.
The 6800 was Motorola’s first microprocessor and was introduced in 1974. |
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