What does MOV mean in assembly?
What does MOV mean in assembly?
Move
mov — Move (Opcodes: 88, 89, 8A, 8B, 8C, 8E.) The mov instruction copies the data item referred to by its second operand (i.e. register contents, memory contents, or a constant value) into the location referred to by its first operand (i.e. a register or memory).
What does MOV instruction do?
The MOV instruction moves data bytes between the two specified operands. The byte specified by the second operand is copied to the location specified by the first operand. The source data byte is not affected.
When a 32-bit value is pushed on the stack what happens to ESP?
28 Cards in this Set
| Which register (in protected mode) manages the stack? | ESP |
|---|---|
| When a 32-bit value is pushed on the stack, what happens to ESP? | ESP is decremented by 4 |
| T/F. Only 32 bit values should be pushed on the stack when using the Irvine32 library. | True |
What are the limitations of MOV instruction?
The MOV instruction has a few limitations:
- an immediate value cannot be moved into a segment register directly (i.e. mov ds,10)
- segment registers cannot be copied directly (i.e. mov es,ds)
- a memory location cannot be copied into another memory location (i.e. mov aNumber,aDigit)
- CS cannot be copied to (i.e. mov cs,ax)
What is wrong with MOV CS ax?
MOV CS, AX ; Not allowed (Code segment register is never used as destination). Note: The following must be observed in 8086 instructions: 1. Never mix an 8-bit register with 16-bit, it is not allowed in microprocessor.
What does LDR do in assembly?
The LDR pseudo-instruction is used for two main purposes: to generate literal constants when an immediate value cannot be moved into a register because it is out of range of the MOV and MVN instructions. to load a program-relative or external address into a register.
How do I remove bits in assembly language?
You can clear bits by using the AND -operation. So you can use this operation to mask and flip bit regions in a register. Pass in a constant as the second argument which has bits flipped up you want to keep up. AL is the lowest byte portion of EAX -register so you can do it this way.
What are the limitations of MOV instructions?
The MOV instruction has a few limitations:
- an immediate value cannot be moved into a segment register directly (i.e. mov ds,10)
- segment registers cannot be copied directly (i.e. mov es,ds)
- a memory location cannot be copied into another memory location (i.e. mov aNumber,aDigit)
- CS cannot be copied to (i.e. mov cs,ax)
Is assembly a low level language?
An assembly language is a type of low-level programming language that is intended to communicate directly with a computer’s hardware. Unlike machine language, which consists of binary and hexadecimal characters, assembly languages are designed to be readable by humans.
Do assembly language directives execute at runtime?
Instructions are executed at run-time. Directives are instructions for the assembler and thus are not really executed at all. Although correct, directives are instructions for the assembler that may emit instructions that get assembled/linked and then executed at runtime.
How instructions are stored in memory?
An instruction, stored in the memory, is fetched into the control unit by supplying the memory with the address of the instruction. The control unit decodes the instruction in order to find the sequence of operation necessary to execute it.
