Systems Architecture Flashcards
(15 cards)
What is the purpose of the CPU?
Processes data and instructions (and controls the computer)
What is the CPU?
Central Processing Unit
What are the components of the CPU?
CU
ALU
Registers
Cache
Buses
Clock
What are the registers in the CPU?
Section of temporary, high speed memory that stores data (and instructions) to be processed.
Name the registers of the CPU
Program Counter (PC)
Memory Address Register (MAR)
Memory Data Register (MDR)
Current Instruction Register (CIR)
Accumulator (ACC)
What does the PC do?
Increments by 1 to store/hold the memory address of the next instruction to be fetched, decoded, and executed
What does the MAR do?
Stores/Holds memory address of the instruction be fetched (to be read from or written to)
What does the MDR do?
Stores/Holds the data (data value or instructions) that has been fetched (or will be written)
What does the CIR do?
Stores/Holds current instruction (to be decoded and executed)
What does the ACC do?
Stores result of calculations processed by ALU
What does the CU do?
Control Unit
Sends/receives control signals which controls the flow of data in the CPU (moves data around the CPU)
Manages Fetch-Execute cycle for program instructions
What does the ALU do?
Arithmetic Logic Unit
Performs arithmetic calculations and logical operations
(Contains the ACC too)
What is the cache?
Low capacity of high speed memory which stores frequently used data (instructions)
What happens in the fetch part during fetch-decode-execute cycle?
PC displays address in RAM of next instruction
The memory address is copied from the PC into the MAR
PC increments by 1 (to store the memory address of next instruction)
The address is sent across the address bus memory
The instruction/data stored in the memory address is sent along the data bus to the MDR
What happens in the decode part during fetch-decode-execute cycle?
Instructions(/data) from the MDR is accessed by the CU
Opcode(instructions) and Operand (data)
CIR stores the current instruction
