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doc/atari5200.sgml: document splash screen user changeable settings

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Christian Groessler 2021-02-11 20:56:28 +01:00 committed by Oliver Schmidt
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@ -30,7 +30,7 @@ information.
<sect>Binary format<p>
The standard binary output format generated by the linker for the Atari 5200 target
The binary output format generated by the linker for the Atari 5200 target
is a cartridge image. It is of course
possible to change this behaviour by using a modified startup file and linker
config.
@ -219,10 +219,58 @@ you cannot use any of the following functions (and a few others):
<sect>Other hints<p>
<sect1>CAR format<p>
AtariROMMaker (<url url="https://www.wudsn.com/index.php/productions-atari800/tools/atarirommaker"> )
can be used to create a <tt/.CAR/ file from the binary ROM image cc65 generates.
This might be more convenient when working with emulators.
<sect1>Changing the splash screen<p>
The 5200 ROM displays a splash screen at startup with the name of the
game and the copyright year. The year information has a 'Year-2000'
problem, the first two digits are fixed in the ROM and are always "19".
<sect2>Changing the game name<p>
The runtime library provides a default game name which is "cc65
compiled". To change that, one has to link a file which puts data into
the "<tt/CARTNAME/" segment.
For reference, here's the default version used by the cc65 libary:
<tscreen><verb>
.export __CART_NAME__: absolute = 1
.macpack atari
.segment "CARTNAME"
scrcode " cc"
.byte '6' + 32, '5' + 32 ; use playfield 1
scrcode " compiled"
</verb></tscreen>
'<tt/__CART_NAME__/' needs to be defined in order that the linker is
satisfied and doesn't try to include the version of the runtime library.
20 bytes are available in the <tt/CARTNAME/ segment (one line) for the
game/program name.
<sect2>Changing the copyright year / changing the cartridge type<p>
The century is hard-coded to 1900 by the ROM.
There are two digits which can be changed. For example "92" will give
"1992" on the screen.
The default used by the runtime library is
<tscreen><verb>
.export __CART_YEAR__: absolute = 1
.segment "CARTYEAR"
.byte '9' + 32,'8' + 32 ; "98", using playfield 1
</verb></tscreen>
If the second byte of the year in the <tt/CARTYEAR/ segment is 255,
the cartridge is seen as a 'diagnostic' cartridge, and the splash
screen and most of the other startup initializations are bypassed.
<sect>License<p>