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.
|Published (Last):||4 September 2005|
|PDF File Size:||15.16 Mb|
|ePub File Size:||6.30 Mb|
|Price:||Free* [*Free Regsitration Required]|
By calling it with different parameters in the registers mostly ah and al you could access various IO operations, string output and more. Thanks in advance for your answer. Email Required, but never shown.
Sign up using Email and Password. INT X where X is 88086 software interrupt that should be generated Other INT instructions are encoded using two bytes. Sign up using Facebook.
INT (x86 instruction) – Wikipedia
Since the dedicated 0xCC opcode has some 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. 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.
assembly language int 21h Dos Interrupt
Post as a guest Name. BOSS 8 23 This page was last edited on 8 Octoberat 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. 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.
Views Read Edit View history. From Wikipedia, the free encyclopedia. One of the most useful DOS software interrupts was interrupt 0x 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 Abraham Jacob 51 1 1.
INT (x86 instruction)
Geoffrey 6, 2 17 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.
This simply means that you are using function 01h of the Interrupt type