Systems Architecture Flashcards
(27 cards)
What is a general purpose computer
A computer designed to carry out a wide range of instructions
What can a general computer do
- access internet
- browse World Wide Web
- use word processing software
- play games
- communicate by email and social media
- store and retrieve data
What is an application
A software program that allows a user to perform a specific task
What is hardware
The physical parts of a computer system
What is software
Sequences of instructions for a computer- programs that run on a computer
What is secondary storage
Non-volatile memory external to the CPU and used for long term storage of programs and data
What is memory
The part of a computer that stores data
What is the purpose of the CPU
Central processing unit
Process data instructions
To control the rest of the computer
What are the processes of fetch-decode-execute
1 The memory address held in the program counter is copied into the MAR.
2 The address in the program counter is then incremented (increased) by one. The program counter now holds the address of the next instruction to be fetched.
3 The processor sends a signal along the address bus to the memory address held in the MAR.
4 The instruction/data held in that memory address is sent along the data bus to the MDR.
5 The instruction/data held in the MDR is copied into the CIR.
6 The instruction/data held in the CIR is decoded and then executed. Results of processing are stored in the ACC.
7 The cycle then returns to step one.
What 6 components does the cpu consist of
-control unit
-arithmetic logic unit
-registers
-cache
-buses
-clock
What does the control unit (CU) do?
It fetches the decodes and executes instructions
It issues control signals that control hardware
It moves data around the system
What does the arithmetic logic unit (ALU) do?
It performs arithmetic and logical operations, and is where calculations are done, and where decisions are made
It acts as a gateway between primary memory and secondary storage
What does the cache do
A small amount of high-speed random access memory built directly within the processor. This is so a faster processing can occur for repeated instructions
What do registers do?
Small amounts of high-speed memory contained within the CPU
Stores:
Next instruction to be executed
Current instruction being decoded
Results of calculations
What kinds of registers are there
Program counter
Memory address register (MAR)
Memory data register (MDR)
Current instruction register (CIR)
Accumulator (ACC)
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 data is to be transferred
What does the memory data register MDR do?
Holds the contents found at the address held in 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 does the accumulator (ACC) do?
Holds the data being processed and the results of processing
What factors affect the CPU performance?
Clock speed
Cache size
Number of cores
What is clock speed?
The speed of a computers CPU measured in hertz. This indicates the number of fetch- decode-execute cycles that can run per second.
What does cache size do?
The bigger it’s cache, the less time a processor has to wait for instructions to be fetched
What do cores do and how do they effect the speed of processing
A processing unit within a CPU is known as a core. Each core is capable of fetching decoding and executing its own instructions.
The more cores a CPU has the greater number of instructions it can process - quicker
