INT 21H 8086 PDF

Posted In Sex

MS-DOS uses INT 21H for its main API functions which provide a low-level is the assembly code to transfer data from one file to other using INT 21H?. INT is an assembly language instruction for x86 processors that generates a software interrupt. For example, INT 21H will generate the software interrupt 0x21 (33 in decimal), causing the function pointed to by the 34th vector in the interrupt. int 21h Dos Interrupt. Int 21h is a common function. The INT 21H instruction in is a software interrupt to vector 21H. It is used for input/output operations.

Author: Zolodal JoJolrajas
Country: Malaysia
Language: English (Spanish)
Genre: Automotive
Published (Last): 14 February 2016
Pages: 466
PDF File Size: 1.79 Mb
ePub File Size: 12.79 Mb
ISBN: 928-7-72010-476-3
Downloads: 5014
Price: Free* [*Free Regsitration Required]
Uploader: Gardajinn

I’m new to learning assembly language, and I’m wondering what the command int 21h means. This is accomplished by entering a bit value corresponding to a kernel function into the EAX register of the processor and then executing INT 0x It is therefore entirely possible to use a far-call instruction to start the interrupt-function manually after pushing the flag register.

int 21h Dos Interrupt

Instruction Set Reference Manual”. INT is an assembly language instruction for x86 processors that generates a software interrupt.

When generating a software interrupt, the processor calls one of the functions pointed to by the interrupt address table, which is located in the first bytes of memory while in real mode See Interrupt vector.

  ALLEGATO A70 PDF

Sign up using Facebook. This simply means that you are using function 01h of the Interrupt type It comes under type 21h of various interrput tables, hence the lines of code goes like these as you mentioned. One of the most useful DOS software interrupts was interrupt 0x From Wikipedia, the free encyclopedia.

INT (x86 instruction)

INT X where X is the software interrupt that should be generated By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. Geoffrey 6, unt 17 Post as a guest Name. By using inh site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Sign up using Email and Password. This page was last edited on 8 Octoberat Depending on the context, compileror assemblera software interrupt number is often given as a hexadecimal value, sometimes with a prefix 0x or the suffix h. Thanks in advance for your answer. Other INT instructions are encoded using two bytes.

Stack Overflow works best with JavaScript enabled. Views Read Edit View history.

What does “int 21h” mean in Assembly? – Stack Overflow

Email Required, but never shown. BOSS 8 23 By 12h it with different parameters in the registers mostly ah and al you could access various IO operations, string output and more. Retrieved from ” https: It takes the interrupt number formatted as a byte value.

  KOSTAL 10.1 PDF

Philip Kirkbride 7, 26 82 The INT 3 instruction is defined for use by debuggers to temporarily replace an instruction in a running program in order to set a breakpoint. Most Unix systems and derivatives do not use software interrupts, with the exception of interrupt 0x80, used to make system calls.

Abraham Jacob 51 1 1.

jnt Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued unt of the website is subject to these policies. For example, INT 21H will generate the software interrupt 0x21 33 in decimalcausing the function pointed to by the 34th vector in the interrupt table to be executed, which is typically a DOS API call.

By using this site, you agree to the Terms of Use and Privacy Policy. Sign up or log in Sign up using Google. Since the dedicated 0xCC opcode has 12h desired special properties for debugging, which are not shared by the normal two-byte opcode for an INT 3, assemblers do not normally generate the generic 0xCD 0x03 opcode from mnemonics.