ARCHITECTURE OF 8051

ARCHITECTURE OF 8051:

Each block will be discussed step by step:

ALU — Arithmetic Logical Unit

This unit is used for the arithmetic calculations.

A-Accumulator

This register is used for arithmetic operations. This is also bit addressable and 8 bit register.

B-Register

This register is used in only two instructions MUL AB and DIV AB. This is also bit addressable and 8 bit register.

PC-Program Counter

Points to the address of next instruction to be executed from ROM• It is 16 bit register means the 8051 can access program address from 0000H to FFFFH. A total of 64KB of code. 16 bit register means.

Initial value     0 00 0         00 0 0          0 00 0         0 000       (0000H)

Final value       1 11 1         11 1 1          1 11 1         1 111        (F FFFH)

Initially PC has 0000H

ORG instruction is used to initialize the PC ORG 0000H means PCinitialize by 0000H

PC is incremented after each instruction.