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Unit 1- computer systems (Input devices (Keyboard, Mouse, Touch screen,…
Unit 1- computer systems
Input devices
Keyboard
Mouse
Touch screen
Graphics tablet
Microphone
Output devices
Speakers
Headphones
Printer
Projector
Monitor
Parts of a Von Neumann Computer
Arithmetic Logic Unit
Performs all the mathematical and logical operations
Register
A small amount of fast access storage that saves temporarily
Control Unit
Directs the flow of instructions and/or data. Also controls the clock
Buses
Address bus
Carries information on to where the data is held in RAM
Control bus
Carries control signals internally and to peripherals
Data bus
Carries data between points
The Fetch-Decode-Execute cycle
These are the steps to processing instructions given by a currently running program:
The processor- checks the program counter to see which instruction to run next
The program counter- gives an address value in the memory where the next instruction is.
The processor fetches the instruction value form this memory location.
Then it needs to be decoded and executed. Eg, this could involve taking one value, putting it into the ALU, then taking a different value from a register and adding the two together.
Once this is complete , the processor goes back to the program counter to find the next instruction.
The process is repeated until the program ends.