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update Atari description

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git-svn-id: svn://svn.cc65.org/cc65/trunk@3572 b7a2c559-68d2-44c3-8de9-860c34a00d81
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cpg 2005-08-07 21:00:40 +00:00
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@ -155,22 +155,15 @@ APPLE2: The program starts at $800, end of RAM is $8E00, so 33.5K of memory
(including stack) are available. (including stack) are available.
Atari: The startup code will adjust the upper memory limit to the installed Atari: The startup code will adjust the upper memory limit to the installed
memory, considering future graphics memory usage (which is allocated memory detected at runtime. The programmer can adjust the upper memory
at top of RAM). The programmer can specify which graphics mode is limit by setting the __RESERVED_MEMORY__ variable at link time. The
about to be used by defining a variable _graphmode_used, unsigned given __RESERVED_MEMORY__ value will be subtracted from the upper
char, to the mode value (mode values like Atari DOS, 0-31). memory limit used by the runtine. This memory could be used as graphics
(Please note that graphics mode selection isn't supported in the memory, for example.
Atari runtime lib yet!) In the default case (no setting of __RESERVED_MEMORY__) the upper
In the default case the upper memory limit will be $8035 (with Basic memory limit is $9C1F (with Basic cartridge) and $BC1F (without
cartridge) and $A035 (without cartridge). This is the default which cartridge). The program starts at $2E00 by default.
leaves room for the biggest possible graphics mode. If only standard These values are for a 48K or 64K machine.
text mode is used (_graphmode_used = 0), the values are $9C1F (with
Basic) and $BC1F (no cartridge).
The program starts at $1F00 (to leave room for DOS), and the free
memory values are $6135 (24K, Basic, default mode), $8135 (32K, no
Basic, default mode), $7D1F (31K, Basic, mode 0) and $9D1F (39K,
no Basic, mode 0).
These values are for a 48K or 64K machine.
Note: The above numbers do not mean that the remaining memory is unusable. Note: The above numbers do not mean that the remaining memory is unusable.
However, it is not linear memory and must be accessed by other, nonportable However, it is not linear memory and must be accessed by other, nonportable