INT B3 - ZIPKEY - PLAY BACK EXIT KEY FOR ENTRY WITH GIVEN ZIPCODE AH = 77h DX = zipcode region (0-999) CH = last two digits of zipcode (0-99) BX = 16-bit BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware. The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. keycode for a defined ZIPKEY alternate exit key Return: CF set on error AX destroyed CF clear if successful zipcode specification as defined by the BX keystroke is placed in keyboard buffer, as if the user had popped up ZIPKEY and exited by pressing the key specified by BX