Classic Mac experts – do you know if/where the contents of the system error handler area on a Mac Plus (so using 128kB ROMs) are defined?
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Classic Mac experts – do you know if/where the contents of the system error handler area on a Mac Plus (so using 128kB ROMs) are defined?
This area runs from 0x3FFC80 to 0x3FFCFF – between the primary frame buffer and the sound/PWM buffer – on a 4MB system. Memory locations 0x3FFC80-0x3FFCBF seem to be used to store all 16 CPU registers, but the rest seems difficult to figure out.
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Classic Mac experts – do you know if/where the contents of the system error handler area on a Mac Plus (so using 128kB ROMs) are defined?
This area runs from 0x3FFC80 to 0x3FFCFF – between the primary frame buffer and the sound/PWM buffer – on a 4MB system. Memory locations 0x3FFC80-0x3FFCBF seem to be used to store all 16 CPU registers, but the rest seems difficult to figure out.
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Classic Mac experts – do you know if/where the contents of the system error handler area on a Mac Plus (so using 128kB ROMs) are defined?
This area runs from 0x3FFC80 to 0x3FFCFF – between the primary frame buffer and the sound/PWM buffer – on a 4MB system. Memory locations 0x3FFC80-0x3FFCBF seem to be used to store all 16 CPU registers, but the rest seems difficult to figure out.
@me_ i have absolutely no effin idea but love it when peeps ask mega nerdy questions like this
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Classic Mac experts – do you know if/where the contents of the system error handler area on a Mac Plus (so using 128kB ROMs) are defined?
This area runs from 0x3FFC80 to 0x3FFCFF – between the primary frame buffer and the sound/PWM buffer – on a 4MB system. Memory locations 0x3FFC80-0x3FFCBF seem to be used to store all 16 CPU registers, but the rest seems difficult to figure out.
@me_ paging @juneaumichal1 and/or @DosFox ?
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@gloriouscow @me_ I've not heard of this area being used for something before. I can't find info on it neither
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@gloriouscow @me_ I've not heard of this area being used for something before. I can't find info on it neither
@twvd @gloriouscow This seems to be a rather obscure area of memory used by the Mac Plus ROMs.
I noticed accesses to this memory range while analysing the patches applied to the ROM by early Mac emulators (in this case, Spectre for the Atari ST) as my little #marchintosh project
Overall, I counted 39 accesses (read or write), which together make up 17% of all patches to the ROM – not counting replaced device drivers, which are probably handled differently.
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@twvd @gloriouscow This seems to be a rather obscure area of memory used by the Mac Plus ROMs.
I noticed accesses to this memory range while analysing the patches applied to the ROM by early Mac emulators (in this case, Spectre for the Atari ST) as my little #marchintosh project
Overall, I counted 39 accesses (read or write), which together make up 17% of all patches to the ROM – not counting replaced device drivers, which are probably handled differently.
@twvd @gloriouscow Most of the other ROM patches NOP out accesses to unsupported devices or replace code by jumps to additional emulation support, which I still have to analyse.
My overall aim is to get an overview of patches applied to different ROMs (Mac 128/512, Mac Plus, Mac LC ROMs) by emulators such as Aladin/Spectre (Atari ST), Shapeshifter (Amiga), Sheepshaver, Daydream/Darkmatter (NeXT) and Mini vMac.
Ideally, I would love to build a tool to "paravirtualize" the Mac ROM automatically.
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