TERMINATE-AND-STAY-RESIDENT

• TSR IS A SOFTWARE PROGRAM THAT REMAINS IN MEMORY UNTIL IT IS NEEDED, AND THEN PERFORMS SOME FUNCTION.

• AN GOOD EXAMPLE OF A TSR IS A VIRUS SCANNER, WHICH MUST REMAIN LOADED IN MEMORY TO HELP PROTECT YOUR COMPUTER FROM COMPUTER VIRUSES.

TSR

• THE TYPICAL METHOD OF UTILIZING AN INTERRUPT VECTOR INVOLVES READING ITS PRESENT VALUE (THE ADDRESS), STORING IT WITHIN THE MEMORY SPACE OF THE TSR, AND INSTALLING A POINTER TO ITS OWN CODE.

• THE STORED ADDRESS IS CALLED BEFORE OR AFTER THE TSR HAS RECEIVED THE INTERRUPT AND HAS FINISHED ITS PROCESSING.

TSR( TERMINATE BUT STAY RESIDENT)

• TSR PROGRAM IS DIVIDED INTO THREE MAIN PARTS

• EXAMPLE : REAL TIME CLOCK, SCREENSAVER

DATA AREA

RESIDENT ROUTINE

INITIALIZATION ROUTINE