# include <dos.h> void interrupt (*OldInterruptFunction)( ); void interrupt NewInterruptFunction( ); int main( ) { OldInterruptFunction=getvect(0x17); setvect(0x17,NewInterruptFunction); keep(0,(_SS+(_SP/16)-_psp)); return 0; } //--------------------- NewInterruptFunction( ) -----------------------// void interrupt NewInterruptFunction( ) { if(_AH==0x00) { if(_AL==\'@\') { setvect(0x17,OldInterruptFunction); freemem(_psp); } if(_AL>=\'a\' && _AL<=\'z\') _AL-=32; else if(_AL>=\'A\' && _AL<=\'Z\') _AL+=32; } (*OldInterruptFunction)( ); }