1.1 System Architecture Flashcards
What happens in the fetch stage?
- PC value of the address of the next instruction to MAR
- MAR value fetched from Memory and delivered to MDR
- MDR value copied to CIR
- CIR value sent to CU
- CU increments the PC by 1
What happens in the decode stage?
The CU decodes the instruction
What happens in the execute stage?
- CU updates the MAR with value
- MAR value fetched from Memory and delivered to MDR
- MDR value sent to Accumulator or ALU for calculation
- ALU calculation sent to Accumulator
ALU
Performs arithmetic calculations and logical operations
CU
Directs timing and controls the other the other components in the CPU, decodes and executes instructions
Cache
Stores frequently used instructions/data
MAR
Holds the memory address of the current instruction/data to be processed
MDR
Holds the instruction/data to be processed
PC
Holds the address of the next instruction to be executed
Accumulator
Holds the result of an instruction/calculation before transferring it to memory
How does increasing the clock speed affect CPU performance?
More instructions can be executed per second
How does increasing the number of cores affect CPU performance?
More instructions/data can be processed at once, though a program may not always be able to take advantages of multiple cores
How does increasing cache size affect CPU performance?
More frequently used instructions/data can be stored at once. Transferring data to and from it is faster than to and from RAM for it has a faster read/write speed yet is more expensive
Embedded system
A computer system that has a dedicated function as part of a larger device
What does an embedded system use?
A single microprocessor including RAM, ROM and a CPU on a single circuit board
