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C In DOS :: Interrupts ,Interrupt Vector Table IVT, Interrupt Service Routines ISR
Pointers and its types :
- A near pointer is 16 bit long . It uses the current contents in CS register of CPU. Near pointer is limited to 64KB of memory
- A Far pointer is 32 bit long and can access more than 64KB , Huge pointers are also 32 bit long but they use normalization procedure .
Addresses are usually stored in Segment:offset pair and u can use the macro MK_FP to create far
pointers using Segment and offset addresses . Say segment is 0xB000 and offset is 8000 then
MK_FP(0xB000,8000) would give u a far pointer.
The CPU Registers :
Microprocessors usually have internal storage locations to hold intermediate output called 'registers' . There are in all fourteen CPU registers in 80x86 family of processors as given by
(a) Scratch Pad registers : These are data registers , Four in number as given by
- AX : Accumulator , Pseudo variable _AX
- BX : Base ,pseudo variable _BX
- CX : Count ,pseudo variable _CX
- DX : Data , pseudo variable _DX
These are 16 bit registers that can be accessed either as 16 bit or 8 bit entities.
(b) Segment registers : The 8086 family of processors refers to any memory location as Segment (16 Bit ):offset (16 Bit ) pair . Specific segments are accessed using Segment registers . These are under ,
- The CS register identifies the code segment , which contains the program currently under execution.
- Data segment and Extra segment are identified by DS and ES registers
- The Stack segment is identified by SS segment.
(c) Offset Registes :
- Instruction Pointer IP
- Stack Pointer SP
- Base pointer BP
- Source Index SI
- Destination Index DI
(d) Flags Registers :
There are 9 one bit registers and 7 bits are unused.
Interrupts and Interrupt Vector Table
Interrupt occurs as a signal for the microprocessor to stop whatever it is doing currently . It tells the microprocessor that something important has happend and its attention is needed . The signal is usually generated by the hardware , i.e., Say when a key is hit the keyboard interrupt is generated . C provides a library function for generating interrupts called int86().Every interrupt (either software or hardware ) has a number associated with it . For example the number Ketboard interrupt is 9.
When an interrupt is generated , the processor stops its current activity and activates a memory resident routine called Interrupt Service Routine ISR , The addresses of ISRs are stored in low memory area called the Interrupt Vector Table or the IVT.
A sample call to int86() function is given below ,
int86(8,&i,&o)
where i and o are unions of type REGS which is defined as follows
union REGS {
struct WORDREGS x;
struct BYTEREGS h;
};
struct BYTEREGS {
unsigned char al, ah, bl, bh;
unsigned char cl, ch, dl, dh;
};
struct WORDREGS {
unsigned int ax, bx, cx, dx;
unsigned int si, di, cflag, flags;
};
Created on 19th September 2000
1. Interrupt vector table
i want to know the details of interrupt vector table and the service nos.how can i access the ivt
in a system
joejith on 2nd June 2008
2. sir i want the intrrupt code for making virus in c which is coomon code in all virus
sir my sir has asked the answer of this question that what is the common code in all viruses .
they have given me one hint that the code is inturrupt pointer find this code.
pls send this code to me.
thanx
ashwini kumar on 28th May 2008
3. architecture
the int86() function doesnt seem to work on windows might be due to different architecture
......what should i do??are there different isr addresses for working in
windows now?????
because whatever m using doent seem to work...why is that so........m currently following
yashavant kanetkar..
vikram datt rana on 22nd May 2008
4. How can delete directory using intdos()
Dear sir,
How can delete directory using intdos() function .Please send it's code.Thanks
jaipratap singh dhakad on 20th May 2008
5. CPU information
Can you help me to identify my CPU details(vendor name,other details)through DOS based programming in C.I use a 16 bit turbo c/C++ compiler.
sudhanshu kotlia on 7th May 2008
6. Keybord Interrupt
Keybord Interrupt
I want to know how int86() can be used to create an keyboard interrupt. I want a full code
for that in C.
Narndra Verma on 6th May 2008
7. interrupt vector
i want a list of all interrupt service number which we can use in C or C++.
Ganesh Pratap Singh Kushwaha on 25th April 2008
8. How to get Bios password in c program? code plz??
w to get Bios password in c program? code plz??
vaishali patil on 4th April 2008
9. How to get Bios password in c program? code plz??
Hello...
I want to display bios password through c language?
How to do it? If any code plz send it to me?
It's helpful to understand the system programing for bios..
Thanks in advance
Amit Prakash Pawar on 4th April 2008
10. How to get Bios password in c program? code plz??
Hello...
I want to display bios password through c language?
How to do it? If any code plz send it to me?
It's helpful to understand the system programing for bios..
Thanks in advance
Amit Prakash Pawar on 4th April 2008
11. Writing Device Drivers for nVIDIA Geforce 4200 Ti series Graphics Card
I would like to know about nVIDIA chipset and internals
Chintan Desai on 25th February 2008
12. Soun card handling
how can i play wave and midi files using C programing and we want the output through sound card?
Ankur Sachan on 12th February 2008
13. keyboard interfacing program using c51
iam doing a project wherein i need t o develop keyboard interface.
harish on 23rd January 2008
14. Hardware Interrupt
Please tell all the interrupts and about int86 and int86x. give me the list of hardware interrupts using in c programme
Ganesh on 15th January 2008
15. intrrupt
i need usefull tips about c intrrupt & graphics
m.ramkumar on 11th January 2008
16. Computer
BIOS Intrupt Table pdf Needed
Mohammad Bashiri on 14th December 2007
17. sound card access in c language
sir, i am working on a project which require mp3 player with serial port controller , I know how to program serial port but how to write mp3 player by C
Manoj Jaiswal on 10th December 2007
18. sound card access in c language
sir, i amworink on a project which require mp3 player with serial port controller , I know how to program serial port but how to write mp3 player by C
Manoj Jaiswal on 10th December 2007
19. intrupt programming
sir,
I want to wirte hardware program in c language. how to write please details give me.
thanks
vimal on 27th November 2007
20. I want some programs of C++ for reading disk info, for reseting the BIOS.
I want some programs of C++ for reading disk info, for reseting the BIOS.
Jaiprakash d solanki on 2nd November 2007
21. Hardware intrrupt
HOw can create hardware intrrupt using c coding
Deepak Singh on 12th October 2007
22. think about c ?
hello my dear , i want the list of ivt table list with different types of its function
rajesh on 7th October 2007
23. int86 interrupts & information about it.
i want to know about the interrupts in int86 for handling files
pramila khot on 2nd October 2007
24. opertaing system designing
how to start to designed the operating system in c language?and what is the first module?
vishal prajapati on 16th September 2007
25. IVT
Please write me about the IVT(interrupt Vector Table)
anton tamang on 13th September 2007
26. music
how music is played in c
raj yadav on 10th September 2007
27. .wav in c
how wav files are implemented in turbo c
RAJU PRASAD on 10th September 2007
28. interrupts
tell me about all the interrupts and about int86 and int86x
RAJU PRASAD on 10th September 2007
29. .wav in C
Is it possible to play a .wav file in C/C++ only.
If possible then how to do it with interrupts...
And also please tell the best way to study interrupt programming in C.
Ayush Sharma on 7th August 2007
30. IVT
i want to know about Interrupt Vector Table. As i am working in TSR screen saver.
Romasa on 18th July 2007
31. interrupt vectors
name the interrupt vectors of 8086?
prashant saroha on 27th May 2007
32. interrupt vector table
Sir I want to know abut interrupt,Types of interrupt and Interrupt Vector Table?
HARSIMRAN KAUR on 17th April 2007
33. int86 function to deal with monitor resolution
int86 function to deal with monitor resolution without calling inbuilt function so to make the program faster
hariprasad k on 12th April 2007
34. C interrupt
tell me about C interrupt in detail
Manikanth Kumar on 11th April 2007
35. int86 function to initialise CD ROM in C
I want to know the codes to initialise CD ROM in C
santosh v gogoi on 11th April 2007
36. Software Engg.
i want to know about different interrupt available for
file management in C or using int86(),,
how to create,modified,delete,change type etc..
Alpesh Donga on 3rd April 2007
37. playing music in c
how 2 play music in c
prasanth varghese on 7th March 2007
38. details of interrupt vector table and the service routines
i want to know the details of interrupt vector table and the service nos. spacially i want to access the sound card through c programming. can you help me?
Mrinal Sen on 20th February 2007
39. Interrupts
How to Interrupt the System using C-program
&
How to use signal.h combining the interrupt concept yields to SECURITY SOFTWARE
Neo Andreson.K on 14th February 2007
40. how ro read and image (JPG) and process it
how can we read image and process it, can we devide pixel in subpixel. I have thorlab camra, and flypgr cam
kiran sapkl on 9th February 2007
41. datail about IVT and ISR
Can i change the address of the ISR in the IVT for some particular interrupt? if so, how?
i want to know,how i can replace already existing isr with new one using int86 function so
that change should be permanent even if computer starts again. i want simple & full coding in c
sayyed abdul majid on 19th December 2006
42. keyboard interrupt
sir,
i want to know,how i can replace already existing isr with new one using int86 function so
that change should be permanent even if computer starts again.
i want simple & full coding in c(by taking eg. of keyboard).
(in other words, i want to prepare a virus)
dharmender on 27th November 2006
43. using mouse in graphics mode
Sir,i want know about how to initialize mouse in graphics mode and how it works.i also want codes for this.
Yamini Priya on 23rd November 2006
44. Serial Interface
How can i write an ISR for serial interface ie for serial port??
Bhagavath on 29th October 2006
45. interrupt
how can i interrupt the system externally using c program?
kanagaraj on 3rd October 2006
46. int86
I gone through many c books but i found only small material on int86 or on int86x How could we interpt with diffrent hardware using c functions.
manoj jaiswal on 25th September 2006
47. hardware interrupt program
Dear sir,can you tell me what I must notice when programming used by hardware interrupt?Thanks.
breezee on 24th September 2006
48. Keystroke Identify
How can i find the key stroke from the keyboard while working other programs . Pls send a complete/any related code to count the number of key strokes while working in any application
yesu on 23rd August 2006
49. how to make a game like prince in c
can we make a game like prince without pthread.h
please provide me with the code and is there any easy way to test hittest property
sreelal.s.l on 15th July 2006
50. TSR
want to know about TSR and ISR
Bhuban Tandukar on 22nd November 2005
51. Modifying the IVT
Can i change the address of the ISR in the IVT for some particular interrupt? if so, how?
Chetan H Nadiger on 19th October 2005
52. Keybord Interrupt
I want to know how int86() can be used to create an keyboard interrupt. I want a full code for that in C.
Ajeet Kumar Gupta on 30th September 2005
53. Interacting with Sound Card
Hi, could u plz give me some tips on how to send data to the sound port and make the speakers to play that sound data. Is there any interrupt to send data to sound card?
Sekar on 23rd September 2005
54. Mr
How to program keyboard in c using interrupts. I want to:
1. execute "function A" while "up arrow" key is pressed.
2.continue execution of "function A" and execute "function B" at the same
time while "right arrow key" is pressed and still pressing "up" key.
3. continue execution of "function A" after releasing "right arrow" while
still pressing "up arrow".
Nadeem Hamed on 17th September 2005
55. TSR
sir I want to know about TSR
pranav waila on 17th September 2005
56. programmer insisted
hi
ramzan khan on 3rd August 2005
57. dos interrupts in c
sir, i want to know the interrupts of dos that are available in c. please send me the interrupts available.
Karthik.P on 24th July 2005
58. System Programming in C
I want to use DOS interrupts.Please send materials for them.
Ranjith Kumar on 22nd July 2005
59. int86
I want to know about the interrupts of int86 and how they works
vijai on 15th July 2005
60. Int86
I want to know about the interrupts of int86 and how they works.
Tarunarko Sarkar on 3rd May 2005
61. assking material
dear sir
at the time being i am taking the corse known as computer engenering .I want the material
about dos interrupt brife not if you can ples send me
thank you for yor copration
afework bezie on 13th April 2005
62. Sound card access in DOS
How to access sound card,i.e.,making sound through external speaker ,not by internal speaker,in borland c version 3.00.
Subhrajyoti Ghosh on 19th March 2005
63. mouse interrupt
How can i catch mouse interrupt
in run time by just clicking the Mouse to know the
row, col etc. ?
Manoj Pandey on 3rd November 2004
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