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Registers 8086

General Purpose Registers:-   8086 Microprocessors has 8 general purpose registers, each register has its own name: AX :- the accumulator register (divided into AH/AL) BX :- the base address register (divided into BH/BL) CX :- the count register (divided into CH/CL) DX :- the data register (divided into DH/DL) SI :- source index register DI :- destination index register BP :- base pointer. SP :- stack pointer. Segment Register:- CS :- pointer at the segment containing the current program. DS :- generally points at segment where variables are defined. ES :- extra segment register, its up to coder to define its usage. SS :- points at the segment containing the stak Special Purpose registers:- IP :- the instruction pointer. Flags Register :- determines the current state of the processor. The Bus Interface Unit (BIU) contains the following registers::- IP - the Instruction Pointer CS - the Code Segment Register DS - the Data Segment Register SS - the...

Flag Register 8086

Flag Register The flags are a 16-bit register containing 9 one bit flags. Figure gives the diagrammatic representation of the flag register. D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 X/U X/U X/U X/U OF DF IF TF SF ZF X/U AC X/U PF X/U CF Control Flag Overflow Flag (OF):- This flag is set if an overflow occurs. I.e. if the result of a signed operation is large (too large positive number or is too small negative number) enough to be accommodated in a destination register. Direction Flag (DF):- This is used by string manipulation instructions. If this flag bit is ‘0’, the string is ...