This set of Tough Microprocessors Interview Questions & Answers focuses on “Numeric Processor 8087 -2”.
1. Which of the following is not a data transfer instruction?
a) floating point data transfer
b) integer data transfer
c) arithmetic instruction
d) bcd data transfer
View Answer
Explanation: The data transfer instructions are grouped into floating point data transfer, integer data transfer and BCD data transfer.
2. The instruction that performs real or integer multiplication of the specified operand with stack top is
a) AMUL
b) IMUL
c) RMUL
d) FMUL
View Answer
Explanation: The FMUL instruction performs real or integer multiplication of the specified operand with stack top. The specified operand may be a register or a memory location.
3. When the instruction, FDIV is performed, the destination is
a) memory
b) stack top
c) register
d) stack bottom
View Answer
Explanation: If the destination is not specified, the ST(Stack Top) is the destination and source must be a memory operand of short real or long real type.
4. When the instruction, FPREM, is performed, the data stored on to the stack top is
a) dividend
b) divisor
c) quotient
d) remainder
View Answer
Explanation: The instruction divides the stack top (ST) by ST(1), and then stores the remainder to the stack top (ST).
5. If ‘x’ is the value stored at the top of the stack, then the instruction F2XMI calculates the expression
a) 2x
b) 2x+1
c) 2x-1
d) log(2x)
View Answer
Explanation: The instruction F2XMI calculates the expression, 2x-1, where the value ‘x’ is stored at the top of the stack. The result is stored back at the top of the stack.
6. The content of the stack is compared with zero to check whether the content is zero, using the instruction
a) FCOM
b) FIST
c) FCOMP
d) FXAM
View Answer
Explanation: The instruction FIST tests if the contents of the stack top is zero, and the condition code flags are accordingly modified.
7. The instruction that loads log 10 (to the base 2) to stack top is
a) FLDPI
b) FLDLG2
c) FLD2T
d) FLDLN2
View Answer
Explanation: The instruction FLD2T loads the specified constant, log 10 (to the base 2) to the top of the stack.
8. The instructions that are used to program the numeric processor or to handle the internal housekeeping functions are
a) transcendental operations
b) comparison instructions
c) constant operations
d) coprocessor control instructions
View Answer
Explanation: The coprocessor control instructions are used either to program the numeric processor or to handle the internal housekeeping functions like exception handling, flags manipulations, and processor environment maintenance.
9. When the instruction FINIT performs its function, then the TAG status is
a) set
b) empty
c) reset
d) zero
View Answer
Explanation: This instruction performs the same function as the hardware reset. The control word is set to 03FF, and the TAG status is set to empty.
10. The instruction that enables the interrupt structure and response mechanism is
a) FINIT
b) FDISI
c) FENI
d) FLDCW
View Answer
Explanation: The instruction FENI enables the interrupt structure and response mechanism of 8087.
11. The instruction that is used to store the environment of the coprocessor to a destination memory location is
a) FINCSTP
b) FLDENV
c) FFREE
d) FSTENV
View Answer
Explanation: The instruction FSTENV is used to store the environment of the coprocessor to a destination memory location, specified in the instruction using any of the 8086 addressing modes.
12. The instruction that is the NOP instruction of the coprocessor is
a) CNOP
b) FNOP
c) SNOP
d) PNOP
View Answer
Explanation: The FNOP is a NOP instruction of the coprocessor. No internal status or control flag bits change.
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