Can You Briefly Describe Functions Performed By Segment Register, Instruction Pointer Register And Flag Register.


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Segment register
This is a group of 4 (sometimes 6) registers named CS, DS, ES, & SS, (FS, GS) each has 2-byte. These registers are called segment registers, and are used in conjunction with either the IP register or two index registers DI and SI to address various areas of computer memory. CS is the primary register used to fetch the instruction in conjunction with the IP register. DS is the primary register, which is used to point to the data in the computer memory along with the DI or SI registers.

Instruction Pointer Register
This is a very special register, which along with the segment register CS, points to the memory location from where the 'next' instruction will be fetched by the processor. Intel's 8086 family processor have ES instruction pointer register.

Flag Register or Status Register
A special purpose one byte or two-byte register is provided within each CPU, depending upon the particular processor model, called the flag register. Each byte of 'flag register' is further divided into eight parts called the bits. CPU or any other type of computer storage in fact consists of eight bits. Thus data is stored in each byte in the form of 8 distinct bits. Each bit within a byte can either store '1' or '0'.

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