From 43881afca22e2e8d2fc5a36a8519befd97ff1a4b Mon Sep 17 00:00:00 2001
From: Christian Groessler <chris@groessler.org>
Date: Thu, 11 Feb 2021 20:56:28 +0100
Subject: [PATCH] doc/atari5200.sgml: document splash screen user changeable
 settings

---
 doc/atari5200.sgml | 50 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/doc/atari5200.sgml b/doc/atari5200.sgml
index aff212b15..c7e5be73e 100644
--- a/doc/atari5200.sgml
+++ b/doc/atari5200.sgml
@@ -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>