Systems Architecture Flashcards
What does ‘CPU’ stand for
Central Processing Unit
What is the purpose of the CPU
To process data and instructions by constantly repeating the fetch-execute cycle
What are the 4 main components of the CPU
CU, ALU, Registers and cache
Describe the purpose of the CU
The Control Unit sends control signals to direct the operation of the CPU (in the ALU and RAM). It also decodes instructions as part of the fetch-execute cycle
Describe the purpose of the ALU
The Arithmetic Logic Unit performs simple calculations and logical operations
Describe the purpose of the Registers
The registers are temporary storage space for one instruction or address which are used during the fetch-execute cycle
Describe the purpose of Cache
Cache memory is used to store data that is frequently accessed
What is the key feature of Von Neumann Architecture
A computer stores both program instructions and data in the same memory (RAM)
Describe the purpose of the PC
The program counter tracks the RAM address of the next instruction to be fetched
Describe the purpose of the ACC
The accumulator stores the result of mathematical or logical calculations
Describe the purpose of MAR
The memory address register tracks the RAM address of the instruction that is to be fetched.
Describe the purpose of MDR
The memory data register stores the instruction that has been transferred from RAM to the CPU
What happens during the fetch-execute cycle
The PC displays the address of the next instruction to be fetched into RAM which is then copied to the MAR. The PC is incremented where is prepares the CPU for the next instruction to be fetched. The CPU checks the address in RAM matches the MAR. Instruction in MAR is then copied to the MDR and then ALU. It is then decoded and executed where the results are stored in the ACC
What is Cache Memory
Temporary storage for frequently accessed data
How does Cache improve the performance of the CPU
Cache is closer to the CPU than RAM so it provides data and instructions at a faster rate. More cache means computers can store instructions faster
Why do most computers have little Cache
Cache can be costly
What is Clock speed and what is it measured in
Clock speed is a measure of how quickly a CPU can process instructions and it is measured in gHz (3.5gHz is equal to 3.5billion cycles per second)
How does higher clock speed improve the CPU performance
More quick to perform the fetch-execute cycle resulting in better performance as more instructions are processed each second
How does ‘overclocking’ and ‘underclocking’ affect the performance of the CPU
Overclocking: Higher than the recommended rate, which can lead to overheating
Underclocking: Lower than the recommended rate, making it slower but increase the lifespan
What is a Core
A complete set of CPU components where each component can perform its own fetch-execute cycle.
Why would a quad core processor have a higher performance than a dual core processor
A dual: 2 instructions simultaneously
A quad: 4 instructions simultaneously
Why might having multiple cores doesn’t necessarily mean the CPU performance will be better
If one core is waiting for another to finish, performance may not increase at all.
What is an embedded system
A computer built into a larger machine to provide a means of control because a specific pre-programmed task is stored in the ROM
List some examples of embedded systems
Microwave, washing machine, traffic lights
