‘Microprocessors Interview Questions’ -------Part ---5

Microprocessors Interview Questions’
Define EQU directive in 8086 assembly language?
It is used to assign a name to constants used in the programs. Consider the statement ‘corr EQU 07H’ , this would tell the assembler to insert the value 07H... Read more »
How the execution time of an instruction is calculated?
Execution time of an instruction can be determined by multiplying the number of clock pulses needed to execute the instruction by the clock period. Read more »
Write the use of Z bit in opcode?
It is used by REP instruction. Z bit helps to control the loop. It will be repeated the number of items indicated by the CX register or until Z bit dose not match... Read more »
What is the use of V bit in opcode ?
It is used by shift and rotate instructions to determine the number of shifts. V bit is set to 0 if the shift count is to be 1. V bit is set to 1 if the CL register... Read more »
What is the use of D bit in opcode?
D bit: It is used in double operand instruction. It is used to indicate whether the register specified by REG is the source operand (D=0) or the destination operand... Read more »
Write about the following instruction : LES CX, [3483H]
Copy the contents of memory at the displacement of 3483H in DS to CL, contents of 3484H in DS to CH, and copy the contents of memory at displacement of 3485H and... Read more »
Write the difference between CBW and CWD instruction in 8086.
CBW : Convert a byte to a word, sign extend AL Register into a AH Register. CWD : Convert a word to a double word ,sign extend the AX Register into the... Read more »
Define Segment Override Prefix.
Segment Override Prefix : To permit exceptions to the Segment Register usage, a special one byte instruction called a segment override prefix is available . It is... Read more »
What is Unpacked BCD Format ?
Unpacked BCD Format : In Unpacked BCD, there is only one digit per byte and because of this,unpacked multiplication and division can be done. Binary operations act... Read more »
What is AAS instruction in 8086 ?
Adjust Result of ASCII Subtraction This instruction adjust the binary result of SUB or SBB instruction. Read more »
What is the use of Directives in 8086 ?
Directives in 8086 give directions to the assembler during the assembly process but are not translated into machine instruction. Read more »
What is Programmed I/O ?
Programmed I/O : It consists of continually examining the status of an Interface and performing an I/O operation with the Interface when its status indicates that... Read more »
Write about the following instruction :
MOV CS:[BX], DL MOV CS:[BX],DL - It copies a byte from DL Register. Effective Address for the memory location is contained in the BX Register. Normally an... Read more »
What is difference between DIV and IDIV instruction in 8086 ?
DIV : It operates only on unsigned number. IDIV : It operates only on signed numbers. Read more »
What is Packed BCD Format ?
Packed BCD Format : Packed BCD Numbers are stored in two digits to a byte , in 4 bit groups referred to as nibbles. ALU is capable of performing only binary addition... Read more »