types of operating system

Single User
Single-user allows one single user to login at a time. There is no user account database which makes the level of security low and so users cannot protect their files from being viewed, copied or deleted. Examples of this type are DOS and Windows 98.

Multi-user

The Multi-user has a user database account which states the right that users have on certain resources. They are more secure than the single user since access is limited. Example of this is UNIX

MULTI-TASKING/SINGLE TASKING:

multitasking allows one or more programs to run, at time. Each process is given a prioritised amount of time on the processor. Single-user allows are programs to run at a time. It is usually faster than multi-tasking Systems +as some time is taken to in switching in multi-user. But multi-user is more efficient as they allow other tasks to run when a task is not performing any operation. Single-users are more robust, as multi-programs are require to communicate with each other which can cause synchronization problems (deadlock)

Multi Processor/Single Processor: Some Operating System allows for more than one processor to use on the system. This allows more than one task to be run, at a time, on different processors. Windows NT/2000 supports multi processors (up to 4).
Single Processor, Multitasking involves running each of the processor for a given time slice or a single processor where with multi processor, they can all run at the same.