Control unit, Arithmetic logic unit and special purpose registers
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What does the control unit do in the CPU?
It coordinates all the activities taking place in the CPU
Summarise the control units functions.
[]it controls the execution of instructions in the correct sequence []it decodes instruction []it regulates and controls processor timing using regular pulses from the system clock []it send and receives control signals to and from other devices within the computer
What functions does the ALU carry out ?
[]logical operations - these include AND, OR and NOT []Shift operations - The bits in a computer word can be shifted left or right by a certain number of places []Arithmetic operations - These include additions, subtraction, multiplication and division.
What is a register?
A register is a special very fast memory location within the CPU used in the execution of instructions.
Name and explain each special register in a register?
The memory address register (MAR) holds the address of the instruction or piece of data to be fetched or stored. The memory data register (MDR) holds data or a program instruction temporarily when it is fetched from memory or it is sent to memory. The program counter (PC) holds the memory address of the next instruction to be processed. The accumulator (ACC) is a special-purpose, memory location in which results of operations carried out in the ALU are temporarily stored.
What does MAR stand for?
Memory Address Register
What does MDR stand for?
Memory Data Register
What does PC stand for?
Program counter
What does ACC stand for?
The Accumulator
What does the MAR do?
It holds the address of the instruction of piece of data to be fetched or stored
What does the MDR do?
It holds data or a program instruction temporarily when it is fetched from memory or be sent to memory.
What does the program counter do?
It holds the memory address of the next instruction to be processed
What does the Accumulator do?
It is a special-purpose memory location in which results of operations carried out in the ALU are temporarily stored
What is the address in a computer?
Location in the memory?