1.1 Systems Architecture Flashcards
What is a Computer?
An electronic device which:
- takes input;
- processes data;
- delivers output.
What is the Purpose of the CPU?
to fetch, decode and execute instructions
Explain what is meant by Fetching
Fetching the next instruction from main memory (RAM).
Bringing the instruction back into the CPU
Explain what is meant by Decoding
Inspects the instruction and works out what it is that needs doing.
Explain what is meant by Executing
Carries out the instruction
What does the CPU consist of
Arithmetic Logic Unit (ALU)
Control Unit (CU)
Cache
Registers
What does The Von Neumann architecture consist of
Arithmetic Logic Unit (ALU)
Control Unit (CU)
Memory Unit (typically RAM)
Inputs and Outputs
Registers:
Program Counter (PC)
Memory Address Register (MAR)
Memory Data Register (MDR)
Accumulator
What does the PC do
holds address of the next instruction in memory
What does the MAR do
holds the address of where data is to be fetched or stored
What does the MDR do
holds the data fetched from, or to be written to memory
What does the Accumulator do
Holds the results of calculations
What can the CPU’s performance be affected by
- Clock speed
- Cache size
- Number of cores
What is Clock speed
- Measured in Hertz (Hz).
- Number of cycles per second.
- 3.2 GHz clock speed = 3.2 billion instructions can be fetched per second
What is Cache Size
Temporary storage of data and instructions being read to and written from the RAM.
- Stores copies of recent data and instructions.
- Much quicker getting items from the cache than from main memory (RAM).
What is a Core
A core is a complete copy of a CPU.
