Can Anyone Explain The Functions Of Commonly Used Registers In A Computer System?


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Amen Bukhari Profile
Amen Bukhari answered
Different types of registers are used in computers. Some of them are address registers, instruction registers, accumulator registers, status registers, buffer registers, program, control registers, input and output registers, stack pointer register etc.

Address register is also called memory address registers is used to hold the address of the memory location. A 24 bit register can hold about 10 million addresses of an active memory at time. Address register is part of control unit (CU). Instruction register is used to hold the instruction which currently being executed by Control Unit (CU). Program counter register is used to keep the track of program instructions. It holds the address of next instruction to be executed by processor. Buffer register is used to store the contents of data or instructions being read from or written to the memory.

Accumulator is used to store data values so that logical, arithmetic or data transfer operations can be carried out. Status register is used to check the operation of arithmetic logic unit (ALU). If data overflow during operation then output result becomes zero or negative. Stack pointer register is used to store the data which is on the top of stack.
valcano blast Profile
valcano blast answered
Control Unit

The control unit is the circuitry that controls the flow of information through the processor, and coordinates the activities of the other units within it. In a way, it is the "brain within the brain", as it controls what happens inside the processor, which in turn controls the rest of the PC.

The functions performed by the control unit vary greatly by the internal architecture of the CPU, since the control unit really implements this architecture. On a regular processor that executes x86 instructions natively, the control unit performs the tasks of fetching, decoding, managing execution and then storing results. On a processor with a RISC core the control unit has significantly more work to do. It manages the translation of x86 instructions to RISC micro-instructions, manages scheduling the micro-instructions between the various execution units, and juggles the output from these units to make sure they end up where they are supposed to go. On one of these processors the control unit may be broken into other units (such as a scheduling unit to handle scheduling and a retirement unit to deal with results coming from the pipeline) due to the complexity of the job it must perform.

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