Assembly Operands

Question 1

ADD/SUB

Answer 1

add or subtract two operands, storing the result in the first operand. These can be registers, memory locations (limit of one) or constants. For example, ADD EAX, 10 means add 10 to the value of EAX and store the result in EAX

Question 2

XOR

Answer 2

Performing an ‘exclusive or’ of a register with itself sets its value to zero; an easy way of clearing the contents of a register

Question 3

INC/DEC

Answer 3

increment or decrement the value of the operand by one

Question 4

CMP

Answer 4

compare the value of two operands (register/memory address/constant) and set the appropriate EFLAGS value.

Question 5

JMP

Answer 5

as the name implies these instructions allow you to jump to another location in the execution flow/instruction set. The JMP instruction simply jumps to a location whereas the conditional jumps (je, jz, etc) are taken only if certain criteria are met (using the EFLAGS register values mentioned earlier). For example, you might compare the values of two registers and jump to a location if they are both equal (uses je instruction and zero flag (zf) = 1).

Question 6

MOV

Answer 6

Move a value from a register or memory into another register

Question 7

MUL/DIV

Answer 7

Multiply and divide unsigned operands

Question 8

IMUL/IDIV

Answer 8

Multiply and divide signed operands

Question 9

CALL

Answer 9

Call a function

Question 10

RET

Answer 10

Return back to a CALL address

Question 11

PUSH

Answer 11

Set data in a register

Question 12

POP

Answer 12

Remove data from a register