1. Whats the differnce between batch systems,multi-program system ans time-sharing.

Batch processing
Batch processing is execution of a series of programs ("jobs") on a computer without human interaction.
Batch jobs are set up so they can be run to completion without human interaction, so all input data is preselected through scripts or command-line parameters. This is in contrast to "online" or interactive programs which prompt the user for such input. A program takes a set of data files as input, process the data, and produces a set of output data files. This operating environment is termed as "batch processing" because the input data are collected into batches on files and are processed in batches by the program.

Multiprogram system
These terms often cause some confusion. Multi-programming is very common on modern computers. Put simply multi-programming means running more than one program at a time. For example I am typing the answer to your question in a Word Processor program and will cut and paste the answer into my e-mail program to send it. As both these programs are running on my PC at once this is multi-programming. Multi-access is more specialised. Perhaps the most common example you have come across is a bank's network of cash machines all connected to a central computer. As you are typing in your PIN and withdrawing cash in one town someone else may be doing the same at another branch of the bank. The computer system has to respond to both customers' requests at the same time. A system like this which responds to more than one user at a time is called a multi-access (or multi-user) system.

Time-sharing
Time-sharing is sharing a computing resource among many users by multitasking. Its introduction in the 1960s, and emergence as the prominent model of computing in the 1970s, represents a major historical shift in the history of computing. By allowing a large number of users to interact simultaneously on a single computer, time-sharing dramatically lowered the cost of providing computing, while at the same time making the computing experience much more interactive.