Source Index (SI): It stores the offset address of the source. 32-bit index registers are ESI and EDI whereas the 16-bit rightmost are SI and DI. Answer / smithwil. This is used to point destination in some string related operations. DS register can be changed directly using POP and LDS instructions. Execution Unit (EU) 2. There are two types of registers in register set of 8086 microprocessor,they are (1)General purpose registers and (2)Special purpose registers. Destination Index (DI): It stores the offset address of the Destination. index register: An index register is a circuit that receives, stores, and outputs instruction -changing codes in a computer. It points to the data segment memory where the data is resided. In such cases the SI and DI are implemented as source and destination index registers. In 8086 mode, the only two base registers are BX and BP, while the only two index registers are SI and DI. There are 4 general purpose registers in Intel 8086. Its offset is relative … Intel 8086 microprocessor is a first member of x86 family of processors. A segment register is a register that contains the base address, or something related to the base address, of a region of memory. This is used to point the source in some string related operations. General Registers 3.4.

Contents hide 1. As others have indicated, they have special uses with the string instructions.
A segment is a logical unit of memory that may be up to 64 kilobytes long. Unlike 8085, the 8086 addresses a segmented memory. Each General Purpose Register consists of 16 bits. So you need to do something like: mov BH,0; mov BL,AL mov DL,array[BX]; rather than trying to use AL directly as a base register. - They are primarily used to store relative to segment registers the locations of offset addresses of memory locations. They are dependent and get worked by each other. 4) Flag or Status Register. Below is a short description of these two units.

This circuit is also called an address register or a register of modifications. Data Registers 3.2. - The source index and destination index are also used as general purpose register. The Flag or Status register is a 16-bit register which contains 9 flags, and the remaining 7 bits are idle in this register. General Purpose Registers. Each of the registers is 16 bits wide. These 32-bit registers can be used in three ways − As complete 32-bit data registers: EAX, EBX, ECX, EDX. Extra segment (ES) is a 16-bit register containing address of 64KB segment, usually with program data. Data Registers. Learn more Pointers and Indexes in Intel 8086 Assembly registers (AX, BX, CX, DX) and index register (SI, DI) is located in the data segment. Each segment thus contains 64 Kbytes of memory.There are four segment registers such as Code Segment Register (CS), Data Segment Register (DS), Extra Segment Register (ES) and Stack Segment Register (SS).Generally segment register is used to … Four 32-bit data registers are used for arithmetic, logical, and other operations. index register: An index register is a circuit that receives, stores, and outputs instruction -changing codes in a computer. The four segment registers actually contain the upper 16 bits of the starting addresses of the four memory segments of 64 KB each with which the 8086 is working at that instant of time.

- Stack pointer and base pointer are the two pointer registers whereas the Source index and Destination index are the index group of registers. I movsb es:di, ds:si SI and DI can also be used as general purpose index registers. This is base pointer register. Some registers are general-purpose or multipurpose registers, while some have special purposes. - In stacks, data areas might exist, to be able to access such data which contains the BP register.