6.1.1+Accumulator,+IR,+PC

=Accumulator, Instruction Register and Program Counter=


 * For the role the accumulator, instruction register and program counter play in the fetch-decode-execute-store cycle visit page 6.1.2 Acc., IR, PC in machine instr. cycle **


 * [|Accumulator]**
 * The Accumulator is the calculating unit of the ALU, it holds a temporary data within the ALU. It holds the ongoing total of the calculations being performed.


 * [|Instruction Register]**
 * The Instruction Register (IR) holds the actual instruction (opcode) which is being executed by the Processor. (it //only// holds the current instruction)
 * The Opcode (Operation Code) is a part of the instruction that specifies the current operation.


 * [|Program Counter]**
 * The Program Counter holds the Address of the next instruction. When the previous instruction is completed the instruction given in the PC linked instruction is executed.



Written by Jocbe Last Update: 24. September 2010


 * "Opcode." Wikipedia. 10 September 2010. Wikimedia.org. 15 September 2010. https://secure.wikimedia.org/wikipedia/en/wiki/Opcode