84PCE:Ports:003A

Synopsis

Port Number: 003A-003C

Function: Stack Protector Ports

This range of ports holds the location of the bottom of the stack. When the the default address D19881 is written to, a non-maskable interrupt is generated which shuts down the calculator and clears all of RAM. This could potentially have uses such as a hardware breakpoint in z80 mode.

Example

Since the stack protector is extremely simple, this equally simple program will cause a crash.

ld (0D19881h),a
ret