vertical encoding
<processor> An instruction set where a field (a bit or group of bits) of
the instruction word is decoded (either by hard-wired logic or microcode) to
generate signals to control the functional units, as opposed to horizontal
encoding where the instruction word bits are used as the control signals
directly.
With vertical encoding, which combinations of signals and operations are
possible is dictated by the decoding logic; the instruction field can only
select one of these preprogrammed combinations. This has the advantage that many
control signals can be generated based on only a few instruction word bits and
only valid combinations of control signals can be generated, e.g. only one
source driving a bus at once. An instruction set may use a mixture of horizontal
and vertical encoding within each instruction.
(1995-04-23)
Nearby terms:
Version 7 « vertical application « vertical bar «
vertical encoding » vertical loop combination »
vertical microcode » Vertical Redundancy Check
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