Instruction Register (IR). More...
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IR | Entity |
behave | Architecture |
Instruction Register (IR).
It is a part of the control unit.
The output of the IR is 8-bit word. It is divided into two nibbles.
Upper Nibble Lower Nibble
2-state 3-state
CU W-bus
The provided instruction set is:
LDA 0000 Load Accumulator with corresponding memory content
ADD 0001 Add the content of the AC to the content of the memory adder
SUB 0010 Subtract the content of the memory location from the AC
OUT 1110 Transfer the AC content to the output port
HLT 1111 Stop processing data
Fetch = 3 cycles Execute = 3 cycles