NIOS Computer Science Chapter 3 – Computer Software Part 1

Introduction

The computer in a language that the computer understands, i.e., machine language. The machine language consists of only binary digits, i.e. 0 and 1. A Computer language includes various languages that are used to communicate with a Computer machine.

Thus a programming language is a set of rules that provides a way of instructing the computer to perform certain operations.

  • Distinguish between system software and application software.

  • Distinguish between compiler and interpreter.

  • Define operating system and its various functions.

Computer Language:

The languages in which programs are written are called programming languages.

Languages can be classified into following categories.

Machine Languages

  • It is based on the concept of electricity being turned "on" and "off". From this on/off, yes/no, two-stage system.

  • The low-level programming language which is the first generation language developed for communicating with a Computer. It is written in machine code

  • Binary system is based on two digits 0 and 1.

  • Numbers 1, 2 and 3 in the decimal system are represented in the binary system as 1, 10 and 11 respectively.

  • In one system, the letter A is represented as 1000001.

  • In addition, in those early days there was no such thing as software.

  • There was only hardware with electrical on/off switches.

Machine Language Ex:

11110010 011100011 1101 001000010000 0111 000000101011

11110011 01000011 0111 000001010000 1101 001000010100

Assembly Languages

  • Second generation programming language that has almost similar structure and set of commands as Machine language

  • Assembly languages, also known as symbolic languages

  • Use Computer Language/Software

  • The hypothetical machine language segment we saw above is as follows:

    11110010 01110011 1101 001000010000 0111 000000101011

  • This could be expressed in assembly language statement as:

    PACK 210 (8, 13), 02B (4,7)

  • Actually, assembly languages do not replace machine languages.

  • In fact, for an assembly language program to be executed

  • The assembly language program is referred to as a 'source program'.

  • Machine language program is an 'object program'.

  • Assembly language code is very similar in form to machine language code.

  • In fact, assembly languages had a one-to-one correspondence.

  • This one-to-one correspondence was still laborious.

Assembly Language Ex:

PACK 210 (8, 13), 02B (4,7)

PACK 218 (8, 13), 02F (4,7)

Assembly languages offer several advantages:

  • They are more standardized and easier to use than machine languages.

  • They operate very efficiently, although not as efficient as the machine languages.

  • They are easier to debug.

Assembly languages offer several disadvantages:

  • Assembly language programs are usually very long and difficult to debug.

  • Though less abstract than machine languages, assembly language programs are still complex.

  • Though more standardized than machine languages, assembly languages are still machine dependent.

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