Description: Apple II and IIe: Controlling the Reset key
Header: Apple II and IIe: Controlling the Reset key

 On an Apple II or Apple IIe computer, the programmer can control how a BASIC
 program will react when reset or control-reset is pressed. DOS uses three
 special locations which it consults whenever reset or control-reset is
 pressed. Based on the values contained in these memory locations, DOS may
 halt a program, rerun the program, reboot a disk, or take another action you
 specify.

 Changing these values changes the results of typing reset or control-reset
 from the keyboard.

 To discourage users from breaking into a Basic program, some programmers
 change the reset vector to restart a running program whenever reset is
 pressed. Put the following line at the beginning of your program to get this
 effect:

 10 POKE 1010, 102 : POKE 1011, 213 : CALL -1169

 A value is not POKEd into location 1012 because the CALL statement sets
 location 1012 to the correct value for the current situation. When you wish
 to return reset to its normal action, include this Basic line:

 20 POKE 1010, 191 : POKE 1011, 157 : CALL -1169

 You can also force a disk boot to occur whenever reset is pressed. Simply
 change the value of one of the three reset vector locations. An example is:

 30 POKE 1012,1

 You may instruct the reset vector to call one of your own machine language
 routines by placing the address of this routine in locations 1010 and 1011,
 and CALLing the ROM routine at location -1169 to set location 1012. Your
 routine may process information, display a warning message, or do anything
 else you wish.
 Apple Technical Communications


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