What is the function of INT 21h?
INT 21H will generate the software interrupt 0x21 (33 in decimal), causing the function pointed to by the 34th vector in the interrupt table to be executed, which is typically an MS-DOS API call.
What is the function of 02h?
INT 21H functions
| Function number | Description |
|---|---|
| 02h e.g. mov ah,02h int 21h | Display character: Send the character in DL to the standard output device console. |
What is the correct option for DOS exit interrupt?
Exit. Load the return code (0 for normal exit, non-zero for error) into AL, then call the interrupt with function code 4Ch in AH. This is the proper DOS exit routine; however, if you are running your program with DEBUG, this will exit DEBUG.
What is the function of 4CH and INT 21h?
MOV AH, 4CH means store (or “move” (w)) the hexadecimal value 4C into register (w) AH . INT 21H means invoke the interrupt (w) identified by the hexadecimal number 21 .
What does the INT 21h accomplish if ah contains a 4ch?
int 21h is the second line of assembler code. The software interrupt 21h is called. This interrupt, when given the value of 4ch in AH (as is the case here), causes the program to exit immediately.
What does the INT 21h accomplish if ah contains a 4CH?
What is the use of INT3?
Int 3 is a bit special because it is a single byte opcode; unlike the other int $n instructions which require 2. Because it is a single byte, it can be used to place breakpoints in programs by rewriting an existing opcode’s first byte with it.
How does INT work in assembly?
INT is an assembly language instruction for x86 processors that generates a software interrupt. It takes the interrupt number formatted as a byte value. When written in assembly language, the instruction is written like this: INT X where X is the software interrupt that should be generated (0-255).