diff --git a/doc/index.sgml b/doc/index.sgml
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--- a/doc/index.sgml
+++ b/doc/index.sgml
@@ -109,6 +109,9 @@ Main documentation page, contains links to other available stuff.
   <tag><htmlurl url="lynx.html" name="lynx.html"></tag>
   Topics specific to the Atari Lynx Game Console.
 
+  <tag><htmlurl url="pet.html" name="pet.html"></tag>
+  Topics specific to the Commodore PET machines.
+
   <tag><htmlurl url="plus4.html" name="plus4.html"></tag>
   Topics specific to the Commodore Plus/4.
 
diff --git a/doc/pet.sgml b/doc/pet.sgml
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+<!doctype linuxdoc system>
+
+<article>
+
+<title>Commodore PET specific information for cc65
+<author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
+Stefan A. Haubenthal, <htmlurl url="mailto:polluks@sdf.lonestar.org" name="polluks@sdf.lonestar.org">
+<date>2005-05-24
+
+<abstract>
+An overview over the PET runtime system as it is implemented for the cc65 C
+compiler.
+</abstract>
+
+<!-- Table of contents -->
+<toc>
+
+<!-- Begin the document -->
+
+<sect>Overview<p>
+
+This file contains an overview of the PET runtime system as it comes with the
+cc65 C compiler. It describes the memory layout, PET specific header files,
+available drivers, and any pitfalls specific to that platform.
+
+Please note that PET specific functions are just mentioned here, they are
+described in detail in the separate <htmlurl url="funcref.html" name="function
+reference">. Even functions marked as "platform dependent" may be available on
+more than one platform. Please see the function reference for more
+information.
+
+
+<sect>Binary format<p>
+
+The standard binary output format generated by the linker for the PET target
+is a machine language program with a one line BASIC stub. This means that a
+program can be loaded as BASIC program and started with RUN. It is of course
+possible to change this behaviour by using a modified startup file and linker
+config.
+
+
+<sect>Memory layout<p>
+
+cc65 generated programs with the default setup run with the I/O area and the
+kernal and BASIC ROM enabled, which gives a usable memory range of
+&dollar;0400 - &dollar;7FFF (32KB machine).
+All ROM entry points may be called directly without additional code.
+
+Special locations:
+
+<descrip>
+  <tag/Text screen/
+  The text screen is located at &dollar;8000.
+
+  <tag/Stack/
+  The C runtime stack is located at &dollar;7FFF and growing downwards.
+
+  <tag/Heap/
+  The C heap is located at the end of the program and grows towards the C
+  runtime stack.
+
+</descrip><p>
+
+
+
+<sect>Platform specific header files<p>
+
+Programs containing PET specific code may use the <tt/pet.h/ or <tt/cbm.h/
+header files. Using the later may be an option when writing code for more than
+one CBM platform, since it includes <tt/pet.h/ and declares several functions
+common to all CBM platforms.
+
+
+<sect1>PET specific functions<p>
+
+There are currently no special PET functions.
+
+
+
+<sect1>CBM specific functions<p>
+
+Some functions are available for all (or at least most) of the Commodore
+machines. See the <htmlurl url="funcref.html" name="function reference"> for
+declaration and usage.
+
+<itemize>
+<item>cbm_close
+<item>cbm_closedir
+<item>cbm_k_setlfs
+<item>cbm_k_setnam
+<item>cbm_k_load
+<item>cbm_k_save
+<item>cbm_k_open
+<item>cbm_k_close
+<item>cbm_k_readst
+<item>cbm_k_chkin
+<item>cbm_k_ckout
+<item>cbm_k_basin
+<item>cbm_k_bsout
+<item>cbm_k_clrch
+<item>cbm_load
+<item>cbm_open
+<item>cbm_opendir
+<item>cbm_read
+<item>cbm_readdir
+<item>cbm_save
+<item>cbm_write
+<item>get_tv
+</itemize>
+
+
+<sect1>Hardware access<p>
+
+The following pseudo variables declared in the <tt/pet.h/ header file do allow
+access to hardware located in the address space. Some variables are
+structures, accessing the struct fields will access the chip registers.
+
+<descrip>
+
+  <tag><tt/PIA1, PIA2/</tag>
+  Access to the two PIA (peripheral interface adapter) chips is available via
+  the <tt/PIA1/ and <tt/PIA2/ variables. The structure behind these variables
+  is explained in <tt/_pia.h/.
+
+  <tag><tt/VIA/</tag>
+  The <tt/VIA/ structure allows access to the VIA (versatile interface
+  adapter). See the <tt/_6522.h/ header file located in the include
+  directory for the declaration of the structure.
+
+</descrip><p>
+
+
+
+<sect>Loadable drivers<p>
+
+<sect1>Graphics drivers<p>
+
+No graphics drivers are currently available for the PET.
+
+
+<sect1>Extended memory drivers<p>
+
+No extended memory drivers are currently available for the PET.
+
+
+<sect1>Joystick drivers<p>
+
+No joystick drivers are currently available for the PET.
+
+
+<sect1>Mouse drivers<p>
+
+No mouse drivers are currently available for the PET.
+
+
+<sect1>RS232 device drivers<p>
+
+No serial drivers are currently available for the PET.
+
+
+
+<sect>Limitations<p>
+
+
+
+<sect>Other hints<p>
+
+<sect1>Passing arguments to the program<p>
+
+Command line arguments can be passed to <tt/main()/. Since this is not
+supported by BASIC, the following syntax was chosen:
+
+<tscreen><verb>
+    RUN:REM ARG1 " ARG2 IS QUOTED" ARG3 "" ARG5
+</verb></tscreen>
+
+<enum>
+<item>Arguments are separated by spaces.
+<item>Arguments may be quoted.
+<item>Leading and trailing spaces around an argument are ignored. Spaces within
+      a quoted argument are allowed.
+<item>The first argument passed to <tt/main/ is the program name.
+<item>A maximum number of 10 arguments (including the program name) are
+      supported.
+</enum>
+
+
+<sect1>Program return code<p>
+
+The program return code (low byte) is passed back to BASIC by use of the
+<tt/ST/ variable.
+
+
+<sect1>Using extended memory<p>
+
+The extended memory at $9000 of the CBM 8x96 may be added to the heap by using
+the following code:
+
+<tscreen><verb>
+    /* Check for the existence of RAM */
+    if (PEEK(0x9000) == POKE(0x9000, PEEK(0x9000)+1)) {
+        /* Add it to the heap */
+        _heapadd ((void *) 0x9000, 0x2000);
+    }
+</verb></tscreen>
+
+
+<sect>Bugs/Feedback<p>
+
+If you have problems using the library, if you find any bugs, or if you're
+doing something interesting with it, I would be glad to hear from you. Feel
+free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
+name="uz@cc65.org">).
+
+
+
+<sect>License<p>
+
+This software is provided 'as-is', without any expressed or implied
+warranty.  In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+<enum>
+<item>	The origin of this software must not be misrepresented; you must not
+	claim that you wrote the original software. If you use this software
+	in a product, an acknowledgment in the product documentation would be
+	appreciated but is not required.
+<item>	Altered source versions must be plainly marked as such, and must not
+	be misrepresented as being the original software.
+<item>	This notice may not be removed or altered from any source
+	distribution.
+</enum>
+
+</article>
+
+
+