What is Int 21h in assembly language?
int 21h means, call the interrupt handler 0x21 which is the DOS Function dispatcher. the “mov ah,01h” is setting AH with 0x01, which is the Keyboard Input with Echo handler in the interrupt.
What is the function of 0Ah of INT 21h?
INT 21H functions
|09h e.g. mov ah,09h int 21h||String output: Send a string of characters to the standard output. DX contains the offset address of string. The string must be terminated with a ‘$’ sign.|
Which function of INT 21 is used for the interrupt hook?
INT 21h / AH=35h – get interrupt vector; entry: AL = interrupt number; return: ES:BX -> current interrupt handler.
What is the function of 4Ch under INT 21h?
INT 21h function 4Ch is preferred. Action: Reads a character from the standard input device and echoes it to the standard output device. If no character is ready it waits until one is available.
What is INT in emu8086?
INT is an assembly language instruction for x86 processors that generates a software interrupt. It takes the interrupt number formatted as a byte value.
What is interrupt hook explain with example?
Yes, “hooking” means having your code run when that interrupt fires, but then jumping to handler you replaced when your function is done. So instead of taking over the interrupt completely, you’ve added your function to the head of a chain of handlers. Imagine the IDT as a global array of function pointers.
What is int in emu8086?
Emu8086 combines an advanced source editor, assembler, disassembler, software emulator (Virtual PC) with debugger, and step by step tutorials. This program is extremely helpful for those who just begin to study assembly language. It compiles the source code and executes it on emulator step by step.
Why do we use 30h in assembly language?
The hex representation for that ASCII code is 30h. That means 48 + 7 (or 30h + 7h) is 55 (or 37h), which is the code for ‘7’. (Another way to write the same this is ‘0’ + 7 is ‘7’.
What is INT 21(INT 15h) in emu8086?
The int 21 (int 15h) is “AT Extended Services / APM”. int 21h (int 33) is one of DOS interrupts. IIRC emu8086 supports only limited subset of services and interrupts, so I think you meant int 21h (and I would expect int 15h being unsupported by emu8086).
What does INT 21h mean in an interrupt?
Show activity on this post. int 21h means, call the interrupt handler 0x21 which is the DOS Function dispatcher. the “mov ah,01h” is setting AH with 0x01, which is the Keyboard Input with Echo handler in the interrupt. See: Show activity on this post.
What is the difference between INT 21h and Ah 21h?
INT 21h / AH=6 – Direct console input or output. INT 21h; output Character. INT 21h; get Character from keyboard buffer (if any) or set ZF=1. for input returns: ZF set if no Character available and AL = 00h , ZF Clear if Character available. AL = Character read; buffer is Cleared. INT 21h / AH=7 – Character input without echo to AL.
How to use the DOS interrupt 21h in 8086?
It is one of the most commonly used interrupt while writing code in 8086 assembly language. To use the dos interrupt 21h load ah with the desired sub-function. load other required parameters in other registers. and make a call to int 21h. © 4beginner.com All Rights Reserved.