2. Low Level Programming Language

Microprocessors recognize the binary numbers and they operate in binary numbers. Each microprocessor has its own binary words, meanings and languages. Each machine has its own set of instructions based on the design of its CPU. Binary language is called as machine language. E nglish-like words are used to represent the binary instructions of a machine. This is called as assembly language programs. The general purpose languages such as BASIC, FORTRAN, C, etc. are called as high-level languages. The machine language and assembly language are however specific to a microprocessor, therefore these are termed as low-level languages.

2.1 Assembly language

In assembly language, a word length is of about eight bits. It is called as a byte. Assembly language can have 256 combinations of bytes. Thus the language has 256 words. There can be a various patterns of bytes. With the help of electronic logic gates, these patterns give a specific meaning to each combination of bytes. These are called as an ‘instruction'. Instructions are made up of one word or several words. The set of instructions designed into the machine makes up the machine language that is specific to each microprocessor based system viz. micro-computer.

Thus we can say,

‘Machine language is the binary medium of communication through a designed set of instructions specific to each computer.'

‘Assembly level language is a medium of communication with a computer in which programs are written in mnemonics . An assembly language is specific to a given computer.'

2.2 Assembly language programming

Assembly language programming is generally written by using hexadecimal codes. Programs can be written by using special keyboard equipped with using hex keys. Programs also have instructions to translate these keys into their equivalent binary patterns. The data and instructions are stored in prescribed locations in memory. An operation code is written which accomplishes the intended task(s). These tasks are carried out on ‘operand(s)' by the operation code. 8085 is a typical general purpose microprocessor and has 8-bit word length. Now, let us learn its architecture, working and programming.