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