From 18b223d1b6c72003fb695bc177acc509403fd4b9 Mon Sep 17 00:00:00 2001
From: Paul Gardner-Stephen <paul@servalproject.org>
Date: Sat, 20 Apr 2019 07:22:42 +0930
Subject: [PATCH] increase IRQ rate to ~60hz

---
 c64/kernal/ioinit.s | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/c64/kernal/ioinit.s b/c64/kernal/ioinit.s
index 64047b7a..46998862 100644
--- a/c64/kernal/ioinit.s
+++ b/c64/kernal/ioinit.s
@@ -20,10 +20,13 @@ ioinit:
 	lda #$7f
 	sta $DC0D 		; First disable all
 
-	;; Set timer interval to ~1/50th of a second
-	lda #<20000
+	;; Set timer interval to ~1/60th of a second
+	;; (This value was calculated by running a custom IRQ haandler on a C64
+	;; with original KERNAL, and writing the values of $DC04/5 to the screen
+	;; in the IRQ handler to see roughly what value the timers must be set to)
+	lda #<16380
 	sta $dc04
-	lda #>20000
+	lda #>16380
 	sta $dc05
 
 	;; Enable timer interrupt