kasse: Add comment why we disable IRQs

diff --git a/src/kasse.c b/src/kasse.c
index 4bed5cf5f8380ec00aaf5348b3143250e5f58a6b..c7c2cc471adff599b6d9591bebc259220aa60b7c 100644 (file)
--- a/src/kasse.c
+++ b/src/kasse.c
@@ -412,6 +412,10 @@ int main(void) {
   /* clock CPU at double the speed (a whopping 2 Mhz!) */
   fast();
 
+  /* Manipulate the VDC with IRQs turned off.
+   * KERNALs default IRQ handler will also try to read the VDC status
+   * register, which could interfere with our code trying to read it.
+   */
   SEI();
   vdc_patch_charset();
   CLI();