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Operating systems

1. Software types

   • -open sources
     • ad
       • Anyone can use it,there is no charge for the licence. This is a good advantage as you can improve other peoples programmes to a higher level. Also developers can sell the software they have created. Also you can always re-download the code.
     • dis
       • If you change the code and something goes wrong you wont be able to correct it. Also another disadvantage is that someone could change the code so that it does not work.
   • Off the shelf
     • ad
       • An advantage of the software is that you can buy it straight away also it is cheaper than custom-written software. Lots of people use it so there is help if something goes wrong. For example : books , user forums and internet offering
     • dis
       • • Made to suit many people so there may be many features that you never use, making the software more complicated than it needs to be • May not do exactly what you want
   • custom written
     • ad
       • It does exactly what you want it to do. • No one else will have the software so it might mean your company can do something others can’t.
     • dis
       • You cannot have it straight away. It can sometimes take months or year. It is much more expensive than other softwares. Such as off the shelf software.
   • proprietary
     • Software that only works with a specific piece of hardware or company. It has many restrictions placed upon it.

2. vid1/vid2

   • The os controls the overall operation of the computer
   • The os is the central part
   • without the os the computer will not work
   • the os alouds the physical hardware which you can touch to comunicate the computers software.
   • the os has alot of memory access to a lot of desk storage and a fast network connection

3. ad/disadvantages of a operating system