Transcript Softwarex
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 Is written in High level language (C++ VB Python) Is translated by Compiler Object code (Machine Code) And turned into.. Software • Types of software Operating Systems Device Drivers Firmware Systems Software 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 Multitasking Security Interfaces OS 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 Waiting Running 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 DOS Command Line Unix Windows Mac OS Interfaces Xfce GUI KDE Voice Input GNOME Menu Driven Android iOS 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 Utility Software Security Virus Detection Spyware Malware Firewalls Maintenance Disk organisation Defragmenters Common Utilities Free space management Calendars Clock Email Search Facilities Software – Systems • Development Software Writing Programs Development Software Editors 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 Word Processing Spreadsheet Presentation Application Software Graphics Database Stock Control Enterprise Payroll Email Customer Management Cloud Software Browsers Educational Media Games VLE’s 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.