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Computer Science Revision, The actual actions that happen during the…
Computer Science Revision
system software
Operating systems
an operating system is software that manages a computer system.
one of its primary function is to manage resources(memory, disk, input and output)
examples
manages peripherals such as input and output devices
Sending data to output devices, and receiving data from an input device
manages printing using spooling
Data is stored on hard disc/in memory/stored in a queue, and printed when printer is free/in correct order
Benefit of spooling - user can carry on working/log off when waiting for job to print
Manages backing store
Ensures that data is stored and can be retrieved correctly from any disk drive
Creates and maintains filing system such as FAT or NTFS
Organise files in a hierarchical directory structure
Manages memory(RAM)
Ensures that programs/data do not corrupt each other by storing them in a correct memory locations, and prevent apps accessing other data (e.g. a virus accessing a banking app)
Manages processes
Ensures that different processes can utilise the CPU and do not interfere with each other or crash
On a multi-tasking O/S ensures that all tasks appear to run simultaneously
Manages security
Allows creation and deletion of user accounts
Allows users to logon and change passwords
Provides a Human Computer Interface
A Human Computer Interface is the method that you can communicate with the computer, and the computer can communicate with you
Types of HCI
Command Line Interface-a text based interface
GUI- Graphical User Interface (WIMP)
Windows-the screen is made up of areas called windows
Icons-small pictures used to represent commands or files
Menus-menus allow a user to make selections from a list
Pointer-the arrow that appears when using Windows
Touch Screen
voice driven//speech recognition- an input method that converts the human voice into text or instructions that the computer can process
Menu-driven interface-the user is presented with a list of options and they type in the letter or number of their selection
Utility Software
Utility software helps keep our computer working as well as possible
Hardware
Von Neuman Machine - Von Neuman machine consists of 3 components these include arithmetic unit, register and control unit
There is nothing i enjoy more than having a cold drink on a warm summers day. For example its 40 degreees celcisu and i just had a fresh capri sun now that is what i call pleasure in the moment. This is not even te best thing either for example you could be having a ice cold can of fresh coke. I mean like come on. What is truly better than that.
Cache size, clock speed and number of cores
The number of cores affects the progress and makes things faster as it can do multiple things at once.
The cache size remembers your most frequent task so that it can predict and run them faster.
The clock speed is how fast the computer runs and the more you have the better however the better the more costly.
Motherboard
The motherboard is what connects all the components together I.e., the gpu and cpu. It is arguably the most important part in the computer as you need it cause without it all the components in the pc cannot interact with eachother
GPU
Graphical user interace
The Computer System
Parts of a modern day system
Von Neumann Machine
Has 3 parts:
Arhythmical logic unit - This part of the system takes care of all he maths and logic processing
Registers - They are temporary storage Unit
Control Unit - This is the "brains" of the computer and manages instructions and controls the system
CPU - this is similar to the control unit as It run all the controls and executes the main instructions of the computer . . GPU - Stands for Graphic processing unit, his is used to display all the graphics and comes built internally but you can also but a better gpu known as a graphics card
Storage
RAM- loses data when turned off. Stores data for current running programs and their data.
ROM – Stores the boot sequence to help the computer turn on. Does not lose data.
Inputs and outputs
Inputs allows data, such as text, images, video or sound, to be entered into a computer system
Programming
Different Languages
some languages inlcude:
python, java, java script, c, c#, html, css, php, apl, c++, nodejs, jquery and lots more
Error messages
syntax error- syntax error is when you misspell or mistyped
logical error - this is when the code runs fine but doesn't do what you want it to do
The actual actions that happen during the execution cycle depend on the instruction itself
