#include "dos.h"

#include "iostream.h"

void interrupt myfunc_8();

void interrupt myfunc_9();

void interrupt (*prev_8)();

void interrupt (*prev_9)();

int vdustate=1,savestate=0,tickctr=0,ticklimit=182;

//ticklimit(for 10 sec)assuming the clock has fequency of 18.2 Mhz

unsigned ax,dx,si,es;

int adapter=0x3d8; //type of monotor VGE,EGA,CGA etc.

main()

{

unsigned long far *intkbd;

unsigned long far *intclock;

intkbd=(unsigned long far*)(9*4);

prev_9=(void (interrupt far*)())*intkbd;

*intkbd=(unsigned long)myfunc_9;

intclock=(unsigned long far*)(8*4);

prev_8=(void (interrupt far*)())*intclock;

*intclock=(unsigned long)myfunc_8;

keep(0,2500);

return 0;

}

void interrupt myfunc_9()

{

void putvduon();

cout<<"\ninto mufunc_9";

ax=_AX;

enable();

savestate=0;

if(vdustate==0)

putvduon();

_AX=ax;

disable();

(*prev_9)();

return;

}

void interrupt myfunc_8()

{

void putvduoff();

ax=_AX;

if(savestate==0)

{

tickctr++;

if(tickctr>=ticklimit)

{

tickctr=0;

savestate=1;

putvduoff();

}

}

_AX=ax;

(*prev_8)();

return;

}

void putvduon()

{

disable();

cout<<"\ninto putvduon";

ax=_AX;

dx=_DX;

si=_SI;

es=_ES;

_AL=peekb(0x40,0x65);

_ES=es;

_SI=si;

outportb(adapter,_AL);

vdustate=1;

_DX=dx;

_AX=ax;

enable();

return;

}

void putvduoff()

{

ax=_AX;

dx=_DX;

disable();

cout<<"\ninto putvduoff";

outportb(adapter,0x25);

vdustate=0;

_DX=dx;

_AX=ax;

enable();

return;

}