what is hardware
- physical component that forms part of a computer system
- internal/ external
role of cpu
- storage/ input device -> input data -> processed by CPU -> stored or sent -> output device
- fetches instruction from memory and executes them
motherboard
- hardware components (RAM, CPU) can be connected directly to the motherboard
RAM
- volAtile (content of memory is lost if no power to the RAM)
- when full, inactive data removed
- when no more to remove, HDD SSD expand memory
- virtual memory slow (access times)
- when several programs open
ROM
- nOn volatile (permanent)
- small long life battery
- one program (e.g instruction to boost comp)
hard drive
external hard drive
- common form of secondary storage
- cheap
- non volatile
external
- USB port
- back up
- expensive
- transfer data
SSD
- non volatile
- flash memory
- fast
- expensive
reasons why a user may want to save data to secondary storage
- make changes to a doc
- keep files for archive for future
- back up
- in a database, each new record saved
what is software
- programs that give instructions to the computer
- program consist of programming code that give instructions ,, cary out task
- e.g. word processing
what is system software
- maintain / operate the comp system/hardware
-
what does an operating system do
manages hardware
manages communication between hardware and software
how does an OS manage hardware
- allocating memory to software
- sending data and instructions to output devices
- giving each running task a fair share of processor time
device driver
- software in external hardware
- sends customized instructions to that specific component
- e.g ‘print’
utility software
- maintenance on the computer system
what is anti virus
2 main functions ?
deals with adware, spyware
1) antivirus monitor
- if unusual behaviour detect, prevent from execution so no cause damage
2)
how does a compiler work
program written in high level language (o.g file is source file )
compiler translates so machine code (containing the object file) can understand
obj file distributed to resellers, customers, individual comps
can on the OS for which compiler had translated
ready for execution
how does an interpreter work?
does the same thing as compiler
but instead of whole source code, one line at a time
less efficient , more time
used when testing programs (executing only parts of the program) on the fly
application software
- programs intended to carry out a task
- word processor
user interface
CLI
3 GUIs
- represents communication between a user and computer system
- user enter text commands , comp system responds by producing text results
- very little memory (old / small systems)
- complex operations
- hard to learn , ez mistake
- windows : area of screen devoted to a specific task
- icons: image rep program/file/task
- pointer: movement from panting device
