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What is DS instruction?
The DS instruction is the best way of symbolically defining storage for work areas, input and output buffers, and so on. Although the formats are identical, there are two differences in the specification of subfields. They are: The nominal value subfield is optional in a DS operand, but it is mandatory in a DC operand.
What does MOV DS ax mean?
A typical “small model” program will start with something like: mov ax, @Data mov ds, ax. In tiny model, you use the same segment for the data and the code. To make sure it’s referring to the correct segment, you want to get the 16 bits from CS and copy it to DS.
Whats DS stand for?
dear son
DS is an abbreviation for “dear son” or “darling son.” It’s part of internet slang that has developed for use on forums, social networks, email, and texting.
What is DS and DC statement?
Unlike the DC instruction, the DS instruction causes no data to be assembled. Therefore, you do not have to specify the nominal value (sixth subfield) of a DS instruction operand. The DS instruction is the best way of symbolically defining storage for work areas, input and output buffers, and so on.
How does the MOV instruction work?
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). The push instruction places its operand onto the top of the hardware supported stack in memory.
What is the meaning of instruction mov ax 0005H?
Immediate addressing mode
The instruction, MOV AX, 0005H belongs to the address mode In Immediate addressing mode, immediate data is a part of instruction and appears in the form of successive byte or bytes.
How is the movs instruction used in a doubleword?
The MOVS instruction is used to copy a data item (byte, word or doubleword) from the source string to the destination string. The source string is pointed by DS:SI and the destination string is pointed by ES:DI. The following example explains the concept −
Where does mov eax, DWORD PTR DS mean?
The instruction you quote moves the DWORD (a 32-bit/4-byte value) in memory location specified by ESI into register EAX. In your case, memory location 00402050, read as a DWORD, contains 34333231.
Where does the MOV instruction copy the data?
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). While register-to-register moves are possible, direct memory-to-memory moves are not.
What does DS mean in protected mode instruction?
In protected mode DS is a selector, not a segment. It defines physical address, permissions and other properties. Normally, an instruction such as the one in your example, uses DS by default, but this can be overridden (by instruction prefixes) to use a different one (ES, FS, GS, SS etc.)