2 ITSIAC Accumulator register, ACC, for arithmetic operations. Instruction has Operation code and storage address, A.(A) means "the contents of location A"The CPU contains an Arithmetic and Logic Unit, ALU
3 Machine Language instruction set Instruction ExplanationADD ACC ACC + (A)SUB ACC ACC - (A)LOAD ACC (A)STORE (A) (ACC)BRANCH BRANCH to ACOND BRANCH if ACC = 0 BRANCH to A
4 RegistersCSIAR(Control Storage Instruction Address Register) points to the next microinstruction to be executed.MIR(Microinstruction Register): contains the current microinstruction being executed.PSIAR(Primary Storage Instruction Address Register) primary storage address of the next machine language instruction to be interpreted.SAR(Storage Address Register) the address of the location in primary storage being accessed.SDR(Storage Data Register) holds the dataTMPR(Temporary Register) the address portion of the machine instruction in the SDR so that it can be placed in the SAR
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