Apple II manual

Models: II

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User Modifications:

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You may wish to add some of your own instructions to this implementation of SWEET 16. If you use the unassigned opcodes $0E and $0F, remember that SWEET 16 treats these as 2-byte instructions. You may wish to handle the break instruction as a SWEET 16 call, saving two bytes of code each time you transfer into SWEET 16 mode. Or you may wish to use the SWEET 16

BK (break) op as a 'CHAROUT' call in the interrupt handler. You can perform absolute jumps within SWEET 16 by loading the ACC (R0) with the address you wish to jump to (minus 1) and executing a ST R15 instruction.

Page 55
Image 55
Apple II manual