Software Software essential is coded programs that perform a serious of algorithms. Instructions loaded into primary memory (RAM) from secondary storage FDE Cycle performed on instructions as software is running. CPU runs software from machine code. However Most software is written in higher level languages. Software High level language (C++ VB Python) Compiler Object code (Machine Code) Is written in Is translated by And turned into..

Software Types of software Systems Software Operating Systems Device Drivers Firmware Servers Utilities Interfaces Development tools

Software - Systems Operating Systems Early computers could only run one program at a time. Code was fed into a computer through punch cards or tape Program then ran until completed or crashed. OS developed to make the hardware transparent. Developed further into multitasking.

Software - Systems Operating Systems OS Multitasking Security Interfaces Peripheral Management File Management Process Management

Software - Systems Operating Systems Multitasking Allows processes to be attended to in the most efficient way. Mutliple processes are loaded into RAM and can be switched between Processes can be either: Runnable RunningWaiting

Software - Systems Operating Systems Security Prevents overwriting of date. Divides memory into pages and keeps tabs on which processes are using which pages to prevent conflicts. Manages user profiles and access rights for multiuser networks. OS Firewalls.

Software - Systems Operating Systems Interfaces Command Line DOS Unix GUI Windows Mac OS Xfce KDE GNOME Android iOS Voice Input Menu Driven

Software - Systems Device Drivers Software to inform the OS how to control the Devices attached to a computer One for each peripheral and written by the device manufacturers. Occasionally there are generic device drivers – USB Requests are passed onto the device drivers and these are translated into code necessary for the device to perform the request. Works on Interrupts to the OS. Comes with User settings.

Software - Systems Firmware Usually required for smaller devices that do not have much RAM Stored on ROM Can provide simple functionality such as in a remote control up to a fully fledged operating system like on DVD players

Software - Systems Server Software that responds to requests from “Clients” Web server software (e.g. Apache) responds to web browser requests Also used in running Networks. Print Servers, File Servers.

Software - Systems Utility Software Security Virus Detection Spyware Malware Firewalls Maintenance Disk organisation Defragmenters Common Utilities Free space management Calendars Clock Search Facilities

Software – Systems Development Software Editors Writing Programs Text IDEs GUI IDES Compilers Convert High level language to Object code Interpreters Convert high level code to machine code a line at a time Assemblers Linkers Links many object codes to from an executable.

Software - Applications Application software Application Software Word Processing Spreadsheet Presentation Graphics Database Enterprise Stock Control Payroll Customer Management Cloud Software Browsers EducationalVLE’s Media Games

Software - Applications Procurement Off the shelf Adobe CS Suite, MS Office etc.. Readily available Good development process – most bugs discovered and fixed. Good communities and forums for help. Custom Specifically written for specific client Fits requirements of client Bug fixing part of service contract Development costs borne by customer – can be expensive Limited testing

Software - Applications Proprietary and open source software Proprietary Software Clients are licensed to use it. Developer owns the intellectual property Source code hidden Quality for software covered by developers Can be expensive Open Source Developed by a community Source code publically available Anyone can adapt it. No guarantees or contract Developer community is quick to spot errors Free Examples – Linux, Libre Office, Mozilla Firefox, Apache.