Systems Architecture Finished Flashcards
Where do inputted actions go while they are being processed
Primary storage
What are the purposes of the CPU (2)
To process data and instructions
To control the rest of the computer system
What is the CPU comprised of (6)
Control Unit (CU) Arithmetic Logic Unit (ALU) Registers Cache Buses Clock
What does the CU do (3)
Fetches, decodes, executes instructions
Issues signals that control hardware
Moves data around the system
What does the ALU do (2)
Performs arithmetic and logical operations
Acts as a gateway between primary and secondary storage
What are registers
Small amounts of high speed memory contained within the CPU
What bits of data do the registers hold (3)
Address of the next instruction to be executed
The current instruction being decoded
The result of the calculations
What are the different registers (5)
Program counter Memory address register (MAR) Memory data register (MDR) Current instruction register (CIR) Accumulator (ACC)
What is cache
A small amount of high-speed RAM built directly within the processor
What is cache used for
It temporarily holds data and instructions that the processor is likely to use
What does the clock do
Sends regular electrical impulses to synchronise the components
What is clock speed
How many instructions can be performed in a given amount of time, measured in Hertz (Hz)
What is the standard clock speed for modern computers
3 - 5 GHz
3 billion to 5 billion cycles per second
What is a bus
A high speed internal connection
What are buses used for
Sending control signals between the processor and other components
What are the key elements of the Von Neumann architecture (5)
Data and instructions are stored as binary digits
Data and instructions are both stored in primary memory
Instructions are fetched from memory one at a time and in order
The processor decodes and executes an instruction before cycling around to fetch the next instruction
The cycle continues until no more instructions are available
What does the program counter do
Holds the memory address of the next instruction to be fetched from primary memory
What does the memory address register (MAR) do
Holds the address of the current instruction that is to be fetched from memory, or the address in memory to which the data is to be transferred
What does the memory data register (MDR) do
Holds the contents found at the address held by the MAR, or data which is to be transferred to primary memory
What does the current instruction register (CIR) do
holds the instruction that is currently being decoded and executed
What odes the accumulator (ACC) do
Holds the data being processed and the results of the processing
What are the 7 stages of the fetch-decode-execute cycle
The memory address held in the program counter is copied into the MAR
The address in the program counter is then incremented by one. The program counter now holds the address of the next instruction to be fetched
The processor sends a signal along the address bus to the memory address held in the MAR
The instruction held in that memory address is sent along the data bus to the MDR
The instruction held in the MDR is copied into the CIR
The instruction held in the CIR is decoded and then executed. Results of processing are stored in the ACC
The cycle returns to the start
What factors affect a processor’s speed (3)
Clock speed
Cache size
Number of cores
What is overclocking
Increasing how many pulses per second the clock can perform in order to carry out more fetch-decode-execute cycles
