How to generateinterrupt by the combination of ctrl+alt+l key.?

Write a TSR program in C that will clear all the contents of the screen and print your VU ID and Name (BC0000000-Name) at the center of the video text memory available at 0xB8000000 whenever Alt+Ctrl+D combination is pressed from keyboard.

Note that you have to take the backup of the contents of video text memory before clearing the screen. And, whenever Alt+Ctrl+R combination is pressed from the keyboard, all the contents of video text memory should be restored.

//CLRSCREEN AND Character Printing Program
#include<DOS.H>
#include<stdio.h>
void interrupt (*old)();
void interrupt scrnsvr();
//void interrupt (*oldkey)();
//void interrupt newkey();
//void cls();              SALMAN HAIDER

unsigned char far *scr = (unsigned char far*)0xb8000680;
unsigned char far *src = (unsigned char far*)0xb8000000;
unsigned char far *sch = (unsigned char far*)0x00400017;
int i,j;
char charsrc[4000];

void interrupt scrnsvr(){

//saving contents
    for(i=0; i < 4000; i++)
    charsrc[i] = *(src+i);
//Clearing Screen
    for(i=0; i < 4000; i+=2)
    {
        *(src + i) = 0x20;
        *(src + i + 1) = 0x07;
    }
}
//Prints RollNo and Name at Center of Graphics Text Memory
void charPrint(){
    *scr = 0x6D;
    *(scr+1) = 0x70;
    *(scr+2) = 0x63;
    *(scr+3) = 0x07;
    *(scr+4) = 0x31;
    *(scr+5) = 0x07;
    *(scr+6) = 0x34;
    *(scr+7) = 0x07;
    *(scr+8) = 0x30;
    *(scr+9) = 0x07;
    *(scr+10) = 0x34;
    *(scr+11) = 0x07;
    *(scr+12) = 0x30;
    *(scr+13) = 0x07;
    *(scr+14) = 0x32;
    *(scr+15) = 0x07;
    *(scr+16) = 0x32;
    *(scr+17) = 0x07;
    *(scr+18) = 0x39;
    *(scr+19) = 0x07;
    *(scr+20) = 0x37;
    *(scr+159) = 0x07;
    *(scr+160) = 0x53;
    *(scr+161) = 0x07;
    *(scr+162) = 0x61;
    *(scr+163) = 0x07;
    *(scr+164) = 0x6C;
    *(scr+165) = 0x07;
    *(scr+166) = 0x6D;
    *(scr+167) = 0x07;
    *(scr+168) = 0x61;
    *(scr+169) = 0x07;
    *(scr+170) = 0x6E;
    *(scr+171) = 0x07;
    *(scr+172) = 0x20;
    *(scr+173) = 0x07;
    *(scr+174) = 0x48;
    *(scr+175) = 0x07;
    *(scr+176) = 0x61;
    *(scr+177) = 0x07;
    *(scr+178) = 0x69;
    *(scr+179) = 0x07;
    *(scr+180) = 0x64;
    *(scr+181) = 0x07;
    *(scr+182) = 0x65;
    *(scr+183) = 0x07;
    *(scr+184) = 0x72;
}
void restore(){
    for(j=0; j < 4000; j++)
        *(src + j) = charsrc[j];
}
/*
void interrupt newkey(){
    *sch = 24;
    *(sch+1) = 34;
       geninterrupt(0x65);
       charPrint();
       (*oldkey)();
*/

void main(){
//Cls
//  oldkey = getvect(0x09);
//  setvect(0x09, newkey);

    old = getvect(0x65);
    setvect(0x65,scrnsvr);
    keep(0,1000);
//Function
    _AH = 0x09;
       if(_AL==0x1D && _AL==0x38 && _AL==0x20)
     {
      geninterrupt(0x65);
      charPrint();
     }
      else if(_AL==0x1D && _AL==0x38 && _AL==0x13)
    {
      restore();
     }
}
}