Basic Features of PC Hardware

The main internal hardware of a PC consists of the processor, memory and the registers. The registers are processor components that hold data and address. To execute a program the system copies it from the external device into the internal memory. The processor executes the program instructions.

The fundamental unit of computer storage is a bit; it could be on (1) or off (0). A group of nine related bits makes a byte. Eight bits are used for data and the last one is used for parity. According to the rule of parity, number of bits that are on (1) in each byte should always be odd.

So the parity bit is used to make the number of bits in a byte odd. If the parity is even, the system assumes that there had been a parity error (though rare) which might have caused due to hardware fault or electrical disturbance.

The processor supports the following data sizes:

• Word: a 2-byte data item
• Doubleword: a 4-byte (32 bit) data item
• Quadword: an 8-byte (64 bit) data item
• Paragraph: a 16-byte (128 bit) area
• Kilobyte: 1024 bytes
• Megabyte: 1,048,576 bytes