diff --git a/src/mame/drivers/megadriv.c b/src/mame/drivers/megadriv.c
index 881a36d5ed0..ec08573542b 100644
--- a/src/mame/drivers/megadriv.c
+++ b/src/mame/drivers/megadriv.c
@@ -41,6 +41,19 @@
 Known Non-Issues (confirmed on Real Genesis)
     Castlevania - Bloodlines (U) [!] - Pause text is missing on upside down level
     Blood Shot (E) (M4) [!] - corrupt texture in level 1 is correct...
+
+Cleanup / Rewrite notes:
+
+On SegaC2 the VDP never turns on the IRQ6 enable register
+  This is because on the real PCB that line of the VDP isn't
+  connected.  Instead the IRQ6 interrupt is triggered by the
+  line that is used to generate the Z80 interrupt on a standard
+  genesis.  (Once, every frame, on screenline 224)
+
+  I should provide interrupt callback functions for each
+  vdp line state change, which can be configured in the init
+  rather than hardcoding them.
+
 */