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Apple GEOS reserves beside the main app area at $4000-$C000 a secondary app area at $0C00-$2000. While it was an elegant idea to use that secondary area for overlays at the end of the day those 5 kB are just too small. So now overlays go at the end of the main area (as with GEOS 64/128).

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However the stack (usually 1 kB) can be securely placed in the secondary area without effort from the side of the developer. The rest of the secondary area (usually 4 kB) is made available to the developer as (uninitialized) 'EXTBSS'.

git-svn-id: svn://svn.cc65.org/cc65/trunk@5696 b7a2c559-68d2-44c3-8de9-860c34a00d81
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ol.sc
2012-06-08 21:46:51 +00:00
parent 5cf9f585a6
commit ffc06fcea3
4 changed files with 15 additions and 13 deletions
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6
src/ld65/cfg/geos-cbm.cfg
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@@ -1,14 +1,14 @@
SYMBOLS {
__STACKSIZE__: type = weak, value = $0400;
__BACKBUFSIZE__: type = weak, value = $2000;
__OVERLAYSIZE__: type = weak, value = $0000;
__OVERLAYADDR__: type = weak, value = $8000 - __BACKBUFSIZE__ - __OVERLAYSIZE__;
__VLIR0END__: type = weak, value = __OVERLAYADDR__ - __STACKSIZE__;
__STACKSIZE__: type = weak, value = $0400;
__STACKADDR__: type = weak, value = __OVERLAYADDR__ - __STACKSIZE__;
}
MEMORY {
CVT: file = %O, start = $0, size = $40000;
ZP: define = yes, start = $58, size = $1A + $06;
VLIR0: define = yes, start = $0400, size = __VLIR0END__ - $0400;
VLIR0: define = yes, start = $0400, size = __STACKADDR__ - $0400;
VLIR1: define = yes, start = __OVERLAYADDR__, size = __OVERLAYSIZE__;
VLIR2: define = yes, start = __OVERLAYADDR__, size = __OVERLAYSIZE__;
VLIR3: define = yes, start = __OVERLAYADDR__, size = __OVERLAYSIZE__;