From: cpg Date: Sun, 25 Jun 2000 23:10:49 +0000 (+0000) Subject: added Atari entry in Systems chapter X-Git-Tag: V2.12.0~3381 X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=fd7399e82f1e354a1726c351af65fc68ca2a6fff;p=cc65 added Atari entry in Systems chapter git-svn-id: svn://svn.cc65.org/cc65/trunk@132 b7a2c559-68d2-44c3-8de9-860c34a00d81 --- diff --git a/doc/internal.doc b/doc/internal.doc index 6a6c52867..b8703ab2c 100644 --- a/doc/internal.doc +++ b/doc/internal.doc @@ -113,8 +113,8 @@ Systems: -------- Supported systems at this time are: C64, C128, Plus/4, CBM 600/700, the newer -PET machines (not 2001), and the Apple ][ (thanks to Kevin Ruland, who did the -port). +PET machines (not 2001), Atari 8bit, and the Apple ][ (thanks to Kevin Ruland, +who did the port). C64: The program runs in a memory configuration, where only the kernal ROM is enabled. The text screen is expected at the usual place ($400), so @@ -138,9 +138,26 @@ PET: The startup code will adjust the upper memory limit to the installed $8000, so on a 8032 or similar machine, 31K of memory are available to the program. -APPLE2: The program starts at $800, and of RAM is $8E00, so 33.5K of memory +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. 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