SoftwareGCSE COMPUTING

What is software?As you know “hardware” is the physical parts of the

“computer” eg CPU, screen, RAM, Hard Drive etcSoftware is the programs that run on the

“computer”Eg Microsoft WindowsAndroidInternet ExplorerPowerPointComputer Games Virus Checkers Etc.

TypesThere are basically two types of software:

1. System Software1. Operating Systems – that make all the parts of the

“computer” actually operate and work together Microsoft Windows Android OS X

2. Utility Programs – Defragmenters, Virus Checkers, etc3. Translators – Visual Studio

2. Applications – programs to do various jobs or tasks Eg Word processing (Microsoft Word) Web Browsing (Mozilla Firefox)

Computer Start UpAlso know as “boot up” or “booting”A small program to start the computer up

when it is switched on.It is called the BIOS (Basic Input Output

System)It does just enough to get the operating

system loaded.It is stored in ROM (Read Only Memory)

Operating Systems

Microsoft Windows

Apple OS XLinuxAndroidSymbian

Software to “operate” the computer hardware, there is a vast selection of different hardware and application software that must be made to work together.Operating systems are found on almost any device that contains a computer eg mobile phones, video game consoles, personal computersDevices that don’t need an operating system, microwave ovens, washing machines.Why not?Because the hardware and operation is fixed and can be programmed for directly.

Functions of an OSMemory ManagementMulti-tasking/Process ManagementPeripheral ManagementSecurityUser Interface

Memory ManagementWhen you start up a program on the computer, the

OS will copy it from the Hard disk to the main memory (RAM) and gives it the processor the address (location) of where it starts.

The processor can then FETCH, DECODE and EXECUTE each instruction in turn.

When you run a program it will use data, the variable declarations at the start will set up locations in memory, allocating appropriate space, based on the data types. The memory management of the OS needs to manage the space used by the programmes.

Multi-Tasking/ Process ManagementYou as a user run multiple

programs on your PC, the OS will also be running lots of backgrounds tasks as well just to manage the computer itself.

A processor can only execute one instruction at a time (based one a single core!).

THEREFORE the OS has to manage a order of PRIORITY of the programs, as some will be more demanding/crucial than others.

IF the RAM is near full or the processor has not many instructions to deal with, the OS will stop certain functions, i.e. GENIE effects of windows, pause a the film etc.

Peripheral ManagementInput, Output devices and storage, these are hardware components that are not apart of the CPU (processor and main memory)!So a keyboard is, but so is a HARD DISK!

Writing to output devices and storage is slower than the moving data around the CPU. The OS will use buffers (queues) to make sure that data is not lost.Reading data from storage or input devices is also slowSo, again the OS must manage how much processor time each input, output devices or storage gets.

SecurityDepending on the OS, there will be different

levels of security.Username & PasswordsUser level of access

Admin Teacher Pupil

These can also be applied to files (read only, not access to certain levels, passwords etc), but to also network drives.

User InterfaceCurrently you are using Windows 7. You use a

different Windows, click on different Icons, look and choose from different menus and use your Mouse cursor to Point and click on the Icons, Windows and menus.

So you currently use a WIMP (Windows, Icons, Menus and Pointers) user interface.

Before Windows and GUI (graphical user interfaces) was CLI (Command Line Interface)

CLI & GUICLI is hard to use as you must know all the

commands, plus it is VERY hard to layout anything.

GUL or WIMP is completely graphical and use a cursor or touch.