•General purpose register
•There are four 16 bit general purpose registers, i.e. AX, BX, CX, and DX. These are used to store 16- bit data. They can also be used to store 8 bit data and they are referred to AH, AL, BH, BL, CH, CL, DH, and DL.
• AX register: It is also known as accumulator register. It is used to store one of the operands for arithmetic operations.
• BX register: It is used as a base register. It is used to store the starting base address of the memory area within the data segment.
• CX register: It is referred to as counter. It is used in loop instruction to store the loop counter.
• DX register: This register is used to hold I/O port address for I/O instruction.
Stack & base pointer register
SP - stack pointer
–It is 16-bit register
–Always points to top item on the stack
–Offset address relative to SS
–Always points to word (byte at even address)
–An empty stack will had SP = FFFEh
BP - base pointer
–It is 16-bit register
–Primarily used to access parameters passed via the stack
–Offset address relative to SS
Source & Destination index register
•SI - source index register
–It is 16-bit register
–used for pointer addressing of data
–used as source in string processing instructions
–offset address relative to DS
• DI - destination index register
–It is 16-bit register
–used for pointer addressing of data
–used as destination in string processing instructions
–offset address relative to ES
