From 5c580e052b3574b4f29a1de61a8f0082e55d8d00 Mon Sep 17 00:00:00 2001 From: cpg Date: Sun, 7 Aug 2005 21:00:40 +0000 Subject: [PATCH] update Atari description git-svn-id: svn://svn.cc65.org/cc65/trunk@3572 b7a2c559-68d2-44c3-8de9-860c34a00d81 --- doc/internal.txt | 25 +++++++++---------------- 1 file changed, 9 insertions(+), 16 deletions(-) diff --git a/doc/internal.txt b/doc/internal.txt index fdda2359e..0b3df1770 100644 --- a/doc/internal.txt +++ b/doc/internal.txt @@ -155,22 +155,15 @@ APPLE2: The program starts at $800, end of RAM is $8E00, so 33.5K of memory (including stack) are available. Atari: The startup code will adjust the upper memory limit to the installed - memory, considering future graphics memory usage (which is allocated - at top of RAM). The programmer can specify which graphics mode is - about to be used by defining a variable _graphmode_used, unsigned - char, to the mode value (mode values like Atari DOS, 0-31). - (Please note that graphics mode selection isn't supported in the - Atari runtime lib yet!) - In the default case the upper memory limit will be $8035 (with Basic - cartridge) and $A035 (without cartridge). This is the default which - leaves room for the biggest possible graphics mode. If only standard - 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. + memory detected at runtime. The programmer can adjust the upper memory + limit by setting the __RESERVED_MEMORY__ variable at link time. The + given __RESERVED_MEMORY__ value will be subtracted from the upper + memory limit used by the runtine. This memory could be used as graphics + memory, for example. + In the default case (no setting of __RESERVED_MEMORY__) the upper + memory limit is $9C1F (with Basic cartridge) and $BC1F (without + cartridge). The program starts at $2E00 by default. + These values are for a 48K or 64K machine. 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 -- 2.39.5