2. Microprocessor

It is a multi-purpose, programmable device that reads binary instructions from a storage device called memory, processes the data according to the instructions, and then provides results as output. In common practice it is also known as CPU (central processing unit). CPU can be referred as complete computational engine on a single chip. First Microcontroller, Intel 4004 was launched in 1971. It was able to process just 4 bits. It started a new era in electronics engineering. Microprocessor chip was one of the important inventions of the 20^th century. Table 3.1.1 shows the history of micro-processors.

Table 3.1.1 History of Micro-Processors

Applications of microprocessors are classified primarily in two categories:

1. Reprogrammable Systems : Micro computers }
   
2. Embedded Systems : photocopying machine, Digital camera

Microprocessor works or operates in binary digits i.e. 0 and 1, bits. These bits are nothing but electrical voltages in the machine, generally 0 - low voltage level, and 1 - high voltage level. A group of bits form a ‘word'. In general, the word length is about 8 bits. This is called as a ‘byte'. A word with a length of 4 bits is called as a ‘Nibble'.