1. Systems Architecture Flashcards
What is the purpose of the CPU
To process data and instructions by constantly repeating the fetch - execute cycle
What does the control unit do
It sends control signals to direct the operations of the CPU, these are sent to the ALU/RAM
What does the ALU do
It performs simple calculations and logical operations
What is cache memory
It is used to temporarily store data that is frequently accessed. Much faster than RAM but slower access speed
What is Von Neumann Architecture
A computer that stores both program instructions and data in the same memory (RAM)
Program Counter
A register that tracks the RAM address of the next instruction to be fetched.
MAR
A register that tracks the RAM address of the instruction that is to be fetched.
MDR
The MDR stores the instruction that has been transferred from RAM to the CPU.
What is the Fetch - Execute Cycle
1) The PC register displays the address in RAM of the next instruction to be processed
2) PC register increases by 1 to prepare CPU for next instruction to be fetched
3) CPU checks the address in RAM matching address held in MAR
4) Instruction in RAM is transferred to the MDR
5) Instruction in MDR is copied into the CIR
6) The instruction in the CIR is decoded and executed and result stored in the ACC
7) Cycle repeats by returning to the first step and checking the program counter for address of the next instruction
CIR
A register that stores the instruction that has been fetched from RAM and is about to be decoded or executed
What are the 3 factors affecting computer performancce
Cache Memory
Clock Speed
Number of Cores
What is cache memory
Temporary storage for frequently accessed data
How does Cache Memory improve performance
Closer to the CPU than RAM therefore it has a faster access speed
More cache memory means higher performance because repeatedly used instructions can be stored and accessed faster
What are the limitations of Cache Memory
Very costly so computers only have a small amount
