1.1 - Systems architecture Flashcards
What is the purpose of the Program Counter?
The PC holds the address of the next line of the program. It counts through the program line by line.
What is the purpose of the MDR?
The MDR holds the data that has been fetched from memory.
What is the purpose of the MAR?
The MAR stores the memory address from which data will be fetched.
What is the purpose of the ACC?
To store the result of the calculations carried out by the ALU.
What is the role of the CU?
The control unit controls all the other parts of the computer. It sens out signals telling the other parts what to do.
What is the role of the ALU?
To process data using binary maths and logic.
It uses processes such as binary addition and binary shift.
What are clock signals?
Regualr pulses of electricity sent out by the CU. They help coordinate the different parts of the processor.
One clock signal (tick) equals one fetch-decode-execute cycle.
What is the memory unit (RAM)?
The RAM holds the data and instructions that the computer needs while it is working.
What is von Neumann Architecture?
Von Neumann architecture is where both the data and the software that are currently being used are stored in computer memory (RAM).
With this architecture, the task a computer is working on can be changed by simply loading a different program into memory.
What happens during the fetch stage?
Instructions and data are transferred from the memory unit to the CPU.
What happens during the decode stage?
The CU converts a binary number from the RAM into an instruction.
What happens during the execute stage?
The processor carries out the required action.
List the 4 factors which affect performance.
- Clock speed
- Cache size
- RAM size
- Number of cores
What is cache memory?
Memory that is faster than the RAM but it cannot hold as much data.
It is either in the CPU or nearby. If it is outside it is called the external cache.
What is the fetch-decode-execute cycle?
It describes how instructions and data are passed around the processor. It is carried out millions of times per second.
