A microinstruction executing system includes a sequencer for
controlling sequential readout of microinstructions from a ROM for
storage in a microinstruction register and for subsequent decoding
by a decoder.
A microinstruction executing system includes a sequencer for
controlling sequential readout of microinstructions from a ROM for
storage in a microinstruction register and for subsequent decoding
by a decoder.
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It is a memory register inside the CPU. The function is to hold
the current microinstruction. The microinstruction is the bits that
drive the control signal and drive the data path.
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difference between micro operation and microinstruction
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In computer architecture and engineering, a sequencer or microsequencer is a part of the control unit of a CPU. It generates the addresses used to step through themicroprogram of a control store.
Usually the addresses are generated by some combination of a counter, a field from a microinstruction, and some subset of the instruction register. A counter is used for the typical case, that the next microinstruction is the one to execute. A field from the microinstruction is used for jumps, or other logic.
Since CPUs implement an instruction set, it's very useful to be able to decode the instruction's bits directly into the sequencer, to select a set of microinstructions to perform a CPU's instructions.
Most modern CPUs are considerably more complex than this description suggests. They tend to have multiple cooperating micromachines with specialized logic to detect and handle interference between the micromachines.
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In a microprogrammed processor, the hardware
doesn't directly execute the instructions in the
ISA
The hardware executes very simple micro-operations that
are used to implement the instructions
Each instruction specifies a sequence of micro-operations