1.1.1 - CPU Architecture Flashcards
What is a general purpose computer? (With examples.)
A computer that is able to carry out a wide range of tasks
Examples of general purpose computers include tablets, smartphones or game consoles
Tasks that a general purpose computer can be used for (4)
- Accessing the internet
- Playing music or videos
- Communication via email or social media
- Play video games
What does the CPU do
The CPU receives and processes data and instructions
It also controls the rest of the computer system
Describe what a register is
A register is a small amount of high speed memory in the CPU that holds data
Examples of registers
PC, MAR, MDR, CIR, Accumulator
What is the function of the CU?
The CU It controls the cycle of the CPU and decodes instructions
What is the function of the PC?
It stores the address of the next instruction and increases by 1 at the end of the fetch stage
What is the function of the MAR?
Copies the address from the PC and stores the address of the current instruction
What is the function of the MDR?
The MDR holds the data from memory. It gets the address from the MAR.
What is the function of the CIR?
It stores the instruction e.g. “+”
What is the function of the Accumulator?
It stores the current value ready for output
What is the function of the ALU?
It performs any calculations or data comparisons (arithmetic and logic)
What is the purpose of cache?
Cache is a small amount of high speed memory in the processor and holds very frequently used data and instructions
Steps in the fetch decode execute cycle
- The memory address held in the PC is copied to the MAR
- The data from that address is copied to the MDR
- The PC is increased by 1
- The data is copied from the MDR to the CU where it is then decoded and executed
- IF any calculations or comparisons are done, the data is copied to the ALU
- The Accumulator stores the result from the ALU ready for output
- The cycle restarts with the new address in the PC
