<sect>Memory layout<p>
-cc65 generated programs with the default setup run with the I/O area and the
-kernal and BASIC ROM enabled (RAM at $A000 - $BFFF may be used
-for the heap), which gives a usable memory range of $1000 - $1DFF.
+cc65 generated programs with the default setup run with unexpanded memory
+(RAM at $A000 - $BFFF may be used for the heap),
+which gives a usable memory range of $1000 - $1DFF.
All ROM entry points may be called directly without additional code.
Special locations:
<tag><tt/vic20-stdjoy.joy/</tag>
Supports one standard joystick connected to the joysticks port of the VIC20.
+ <tag><tt/vic20-ptvjoy.joy/</tag>
+ Driver for the Protovision 4-player adapter contributed by Groepaz. See
+ <htmlurl url="http://www.protovision-online.de/hardw/hardwstart.htm"
+ name="http://www.protovision-online.de/hardw/hardwstart.htm"> for prices and
+ building instructions. Up to three joysticks are supported.
+
</descrip><p>
</verb></tscreen>
+<sect1>Interrupts<p>
+
+The runtime for the VIC20 uses routines marked as <tt/.CONDES/ type 2 for
+interrupt handlers. Such routines must be written as simple machine language
+subroutines and will be called automatically by the interrupt handler code
+when they are linked into a program. See the discussion of the <tt/.CONDES/
+feature in the <htmlurl url="ca65.html" name="assembler manual">.
+
<sect>Bugs/Feedback<p>