Memory map of the Apple II ROMs(easy68k.com)
easy68k.com
Memory map of the Apple II ROMs
http://www.easy68k.com/paulrsm/6502/MEMMAP.HTM
2 comments
Not being an Apple guy this is the first I've heard of SWEET16. Does anyone know how widely this was used?
Apple II guy here. SWEET 16 was not used that much. The Apple II+ -- introduced 2 years after the original Apple II -- used up the whole ROM space for the BASIC interpreter, so there was no longer room for extra stuff like SWEET 16. The original Apple II only sold ~40,000 units, so the Apple II+ memory map became the standard one.
OTOH, it is true that, pretty early on, it became common for the ROM space to be switchable. Instead of reading the on-board ROM, you could have the system read from ROM (or, with the "Language Card", RAM) on a plug-in card. That means that a typical Apple II-whatever in the 80s would actually have had SWEET 16 available, although somewhat hidden, not well known, and without readily available documentation.
Still, I did a lot of low-level programming, and I never used SWEET 16. Nor did I ever run across any code that did, except stuff sold by Apple, like the Programmer's Aid #1.
OTOH, it is true that, pretty early on, it became common for the ROM space to be switchable. Instead of reading the on-board ROM, you could have the system read from ROM (or, with the "Language Card", RAM) on a plug-in card. That means that a typical Apple II-whatever in the 80s would actually have had SWEET 16 available, although somewhat hidden, not well known, and without readily available documentation.
Still, I did a lot of low-level programming, and I never used SWEET 16. Nor did I ever run across any code that did, except stuff sold by Apple, like the Programmer's Aid #1.