The source index (SI) register is required for some string (character) operations. In this context the SI is associated with the DS register. The destination index (DI) register is also required for some string operations. In this context the DI is associated with the ES register.
The various 16-bit registers on the 8085 are BC, DE, HL, SP, PC.
An index register has the function of receiving, storing, and outputting instruction-changing codes in a computer. The index register is in a computer's CPU.
Address Register are designed to make it easy to index into the array of constant register. The address allows you to provide a signed integer offset into the constant register.
there are 14 registers in 8088 micro processor. All the 14 are 16 bit registers. They are4 segment registers viz - code segment register, stack segment register, data segment register, extra segment register.general registers are - accumulator register i.e. AX, base register i.e. BX, count register i.e. CX, data register i.e. DX and stack pointer (SP), base pointer (BP).index registers are - source index(SI), destination index(DI),and the other registers are instruction pointer and flags register.
The program counter (PC) and the stack pointer (SP).
PC (Program Counter) IX (Index Register X) IY (Index Register Y) SP (Stack Pointer)
DI is the Index register in Data segment(16-bit, 64 KB) .Destination Index (DI) is a 16-bit register. DI is used for indexed, based indexed and register indirect addressing, as well as a destination data address in string manipulation instructions.
The SI (Source Index) and DI (Destination Index) registers are useful in repeated string operations, such as copy. The DS (Data Segment) register is paired up with SI and the ES (Extra Segment) register is paired up with DI.
A segment register is a register that contains the base address, or something related to the base address, of a region of memory. In the 8086/8088, the four segment registers are multiplied by 16 and added to the effective address to form the physical address. An index register, on the other hand, is a register that contains an address that is added to another address to form the effective address. In the 8086/8088, four address components are involved; 1.) the displacement contained within the instruction, often called the offset, 2.) a base address specified by the r/m field, often the BP or BX register, 3.) an index address specified by the r/m field, often the SI or DI register, and 4.) the segment address specified by context or by a segment override prefix, often the CS, DS, SS, or ES register.
A register used to store an address of something in memory. Its invention eliminated the need to write self modifying code.
An index register contains an address that can be used during effective address generation, often along with an offset in the instruction or in another register. This is most useful when accessing elements of arrays or structures. A stack pointer is a specialized index register that points to a region of memory that can store temporary elements, in a last-in-first-out structure, such as return addresses, parameters, and local storage for function calls.