'===========================================================================
' Subject: INTERRUPTS IN QBASIC 2: INSIDEQ   Date: 02-07-97 (22:15)       
' Author:  Rick Elbers                       Code: QB, QBasic, PDS        
' Origin:  rick@tip.nl                     Packet: INTERRPT.ABC
'===========================================================================
'INTERRUPTS IN 2:QBASIC HOOKING INTERRUPTS
'---------------------------------------------------------------
'RICK ELBERS december 1996


Q16: What interrupt vectors are changed by QBASIC ?

A16: When Qbasic is loaded in memory then it changes
     a few interrupt vectors to point to Qbasic routines:
      
      HARDWARE INTERRUPTS HOOKED BY QBASIC:

      INT 0   DIVIDE BY ZERO INTERRUPT
      INT 4   OVERFLOW INTERRUPT
      INT 9   KEYBOARD INTERRUPT
      INT A   LPT 2/EGA,VGA/IRQ 9

      SOFTWARE INTERRUPTS HOOKED BY QBASIC:

      INT 1C  TIMER TICK INTERRUPT
      INT 22  TERMINATE( ADRESS)
      INT 23  CTRL      INT 24  CRITICAL ERROR HANDLER
      INT 2E  COMMAND COM LOADER
      INT 2F  MULTIPLEX INTERRUPT
      INT 34--3F FLOATING POINT EMULATION
      INT EF  BASICs ORIGINAL INT 9 VECTOR!
      INT F0  BASICs ORIGINAL INT 8 VECTOR!
      INT F6  SOMETHING VERY SPECIAL FOR QBASIC!