Define hardware
The physical components of a computer
Define software
Any program that runs on the computer
Define system software and give examples
Manages computer system resources and acts as a platform to run application software
Eg OS
Define application software and give examples
Performs user end tasks
Eg docs
Define utility software
Small programs working in conjunction with the OS
Give 3 examples of utility software
Defragmentation software - stores files in consecutive memory locations
Encryption software - encode text
Data compression software - compress data
What does the OS handle
Processor management
Input output device management
Application management
Memory management
Security management
Characteristics of high level languages
Syntax and structure similar to English
Used most often
Need to be compiled or interpreted
Run on any system
Eg python, Java
Characteristics of low level languages
Used to control specific hardware
Execute very quickly
Machine code executed by processors with unique instruction
Eg assembly language
How do compilers work
Translated at once into machine code to make object code so difficult to debug and needs recompiling after change
Compiled program executed faster
Produces executable file so original code doesn’t need compiling
No need for compiler when object code present
How do interpreters work
Translates and executes one line at a time
Do not generate machine code, call sub routines within own code to run statements
More time to execute
Code translated every time it’s run
Process stopped every time error found so easier to debug
Must be installed to run program
How do assemblers work
Converts assembly language into machine code
Function of ALU
Carry out arithmetic and logical operations
Function of CU
Decodes the instructions
Sends and receives control signals to fetch and write data
Function of clock
Regulates speed and timing of all signals and computer functions
Function of registers
Smallest and fastest memory
Store memory addresses, data and instructions
Function of bus
A collection of wires to transfer data and instructions
Purpose of the cpu
To carry out the fetch decode execute cycle
What is the fetch decode execute cycle
Fetch - instructions fetched from main memory
Decode - instructions decoded in the control unit
Execute - instructions executed
Effect of clock speed, cache size and cores on cpu
Clock speed -Determines number of fetch execute cycles per second
Cache- faster than main memory making cpu more efficient but slower than registers
Cores - each core processes one operation per code cycle, so 4 would process 4 simultaneously
What is RAM (random access memory)
Temporarily store data
Volatile - data lost when power off
Written and read from
Used as computers working memory
What is ROM(read only memory)
Stores instructions that never change
Non volatile- data not lost when power off
Used for start up instructions and embedded systems
Read only
Why is secondary storage needed
Long term storage of data and files as it is non volatile
How do hard disk drives work
Multiple spinning platters at high speed
Each platter split into sectors, data is organised on rings called tracks
Read write head moves to read write data from the disk by magnetising microscopic regions
1 head each side
