1.1.1 Structure and Function of the Processor Flashcards
Performance of the CPU
What three ways can the performance of the CPU be improved?
- Increasing clock speed
- Larger cache size
- Having multiple cores
Performance of the CPU
How does increasing clock speed improve the performance of the CPU?
Control Unit uses a clock
Higher clock speed means more fetch-execute cycles per second, so more instructions can be carried out per second
More heat is produced, though therefore a cooling system is needed
Performance of the CPU
How does having a larger cache improve the performance of the CPU?
The MDR stores data in cache
Cache is a small piece of memory in the processor, which stores frequently used data, thus decreasing fetch time
Increasing cache size means more data can be stored closer than main memory
Performance of the CPU
How does having more cores improve the performance of the CPU?
Each core performs a fetch-execute cycle
Having more cores allows more instructions and cycles to be carried per second, allowing a greater processor speed
This would, however, require more complicated circuitry
Pipelining
Explain the process of pipelining
Multiple instructions are passed through the fetch-execute cycle at one time
As one instruction is being executed, the next one is being decoded
A third instruction is being fetched at the same time
All instructions more through the cycle, having multiple being processed at the same time
Pipelining
What are the limitations of pipelining?
Requires multiple cores to be a viable option
It will only work if the subsequent instruction can be predicted
If the wrong one is fetched, ‘flushing the pipe’ occurs, which when done too often can decrease the benefits of pipelining
‘Flushing the pipe’ is when the instructions are thrown away and the right one is fetched
Structure and function of the processor
What is the name and function of the CPU?
Central Processing Unit
Processes data and executes intructions
Structure and function of the processor
What general components are found inside the CPU?
ALU
CU
Registers (PC, MAR, MDR, CIR, ACC)
Buses (Address, Data, Control)
Structure and function of the processor
Which registers are found within the CPU?
PC (Program Counter)
MAR (Memory Address Register)
MDR (Memory Data Register)
CIR (Current Instruction Register)
ACC (Accumulator)
Structure and function of the processor
What is the name and function of the ALU?
Arithmetic and Logic Unit
Performs arithmetic and logical calculations
Structure and function of the processor
What is the name and function of the CU?
Control Unit
Sends signals to coordinate how the processor works
Controls the flow of data through the CPU, and to Main Memory
Decodes instructions fetched from memory
Structure and function of the processor
What are the roles of registers in the CPU?
Run at fast speeds to perform and control the fetch-decode-execute cycle
Structure and function of the processor
What is the name and function of the PC?
Program Counter
Stores the memory address of the next instruction
Structure and function of the processor
What is the name and function of the MAR?
Memory Address Register
Stores the memory address of the data or instruction that is to fetched or sent
The MAR will equal the PC if it is the location of an instruction, and the MDR will not equal the PC if it is the location of data
Structure and function of the processor
What is the name and function of the MDR?
Memory Data Register
Stores the data that is to be fetched or sent
