diff --git a/doc/cbm610.sgml b/doc/cbm610.sgml
index f70757b26..73f6c975b 100644
--- a/doc/cbm610.sgml
+++ b/doc/cbm610.sgml
@@ -249,6 +249,15 @@ Command line argument passing is currently not supported for the Commodore
 610.
 
 
+<sect1>Interrupts<p>
+
+The runtime for the Commodore 610 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>