Specifies the location of the ROM memory.
$ROMSTART = [&H] address
The (hex)-address where the code must start.
Default is 0. This value will be used when $ROMSTART is not specified.
You can use this option when you want to test the code in RAM.
The code must be uploaded and placed into the specified address and can be called from a monitor program.
The monitor program must relocate the interrupts to the correct address! When $ROMSTART = &H4000 is specified the monitor program must perform a LJMP instruction. For address 3 this must be &H4003. Otherwise interrupts can not be handled correctly. But that is up to the monitor program.
$ROMSTART = &H4000 'ROM enabled at 4000 hex