Interrupt problems

git-svn-id: svn://svn.cc65.org/cc65/trunk@2812 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/doc/cbm610.sgml b/doc/cbm610.sgml
index d9c3bcdf920de9635f37f3fedab0dff70e08b2ce..f70757b26574ecbf4c7b43504a50b3d6c86fc146 100644 (file)
--- a/doc/cbm610.sgml
+++ b/doc/cbm610.sgml
@@ -229,6 +229,16 @@ While this simplifies things, it should be noted that the wrappers do have
 quite an impact on performance: A cross bank call has an extra 300µs
 penalty added by the wrapper.
 
+<sect1>Interrupts<p>
+
+Compiled programs contain an interrupt handler that runs in the program bank.
+This has several advantages, one of them being performance (see cross bank
+call overhead mentioned above). However, this introduces one problem:
+Interrupts are lost while the CPU executes code in the kernal bank. As a
+result, the clock may go wrong and (worse) serial interrupts may get lost.
+
+Since the cc65 runtime does only call the kernal for disk I/O, this means that
+a program should not do file I/O while it depends on interrupts.
 
 
 <sect>Other hints<p>