SESSION 1			INTRODUCTION


1. A computer system comprises HARDWARE, SOFTWARE and DATA.


2. Hardware consists of processor, memory, peripheral devices such as disk 
drives, communication paths, printers, etc.. On its own, hardware is useless.


3. Software (instructions, programs) is required to tell the hardware how
to operate. Software can be grouped into two categories:
	(a) SYSTEM PROGRAMS (e.g. programs which allow you to log on, to 
type commands, write and edit programs) provide the foundation which allows 
individual users to run 
	(b) APPLICATION PROGRAMS (e.g. wordprocessors, spreadsheets, data-
bases, scientific programs perhaps written by you to solve particular 
scientific problems).


4. The OPERATING SYSTEM (OS) is the heart of the computer system software.
This provides the interface between the hardware and the user (you!). In 
this course we will be using the operating system called UNIX.


5. DATA is the third essential ingredient of a computer system. This is 
the information used or produced by the software. Data is usually stored in 
hard disks or tape drives in the form of FILES. Without data, the programs 
have nothing to process. Without a program (instructions), the computer 
cannot process data.


6. The components of the UNIX operating system may be classified into

	(a) KERNEL: this is the core of UNIX containing both input/output 
software (called drivers), and resource management software which allows 
more than one user or program to share the hardware with other users and
programs. UNIX is therefore a multiuser, multitasking operating system.

	(b) TOOLS and UTILITIES: commonly needed programs like editors, 
compilers,.... .

	(c) SHELL: the shell is a command interpreter which initiates user
commands and locates and runs programs. It is also a programming language.
Several shells exist: the c shell, the BOURNE shell, and others. We will 
be using the c shell.


7. The Keyboard. 

	Familiarise yourself with the position of the various keys. Many 
you need not know about at present but a few are especially important. For 
example, the keys marked 

		return (or enter or carriage return)
		control (or ctrl)
		esc     (escape)
		backspace or delete
		/       (slash)

Locate these on your keyboard.

Some commands require two keys to be pressed simultaneously, e.g.

	ctrl c 		(meaning control and c)
	ctrl d		(meaning control and d)    		etc.


7. UNIX command syntax.

UNIX commands usually comprise three components:

	Command name		Options		Arguments

e.g.	ls			-l		phonelist

The command name tells the system which operation or program it should 
perform. This is the only component which must always be given. If options 
and/or arguments are absent DEFAULT values are assumed.

The options, which always begin with a minus (-) to distinguish them from 
arguments, gives more information about what you wish the command to do.
Several options may be invoked simultaneously.

The argument(s) are the objects that commands operate upon.


8. Be aware, before you start, that

		UNIX IS CAse sEnSiTiVe!!!!

i.e. hcb1 is distinguishable from Hcb1. (On the other hand Fortran 
code is NOT!)


9. Finally!

	DONT BE AFRAID TO MAKE MISTAKES. THE SOONER YOU MAKE YOUR FIRST
	THOUSAND MISTAKES THE SOONER YOU WILL BE ABLE TO CORRECT THEM!!!


END OF SESSION 1					file: readme1
