X-Git-Url: https://git.ucc.asn.au/?a=blobdiff_plain;f=ROM2%2Fstart.s;h=c3f8d36f843ee6ed447d81233b4a60d5f5036ffc;hb=c1fd53d73bce8779c822e3ed74de94f40714f9ca;hp=c37026396bd7ad4f54fd1a81b0e2871dfa16c8e4;hpb=41ad37ba6d86ccc4f8f720cb09f7891ae166cb38;p=uccvend-snackrom.git

diff --git a/ROM2/start.s b/ROM2/start.s
index c370263..c3f8d36 100644
--- a/ROM2/start.s
+++ b/ROM2/start.s
@@ -2,6 +2,14 @@
 .globl _start
 
 _start:
+	;; set port a to output
+	ldab #0xfc  ; 11111000
+	stab 0x1001
+
+	;; start chiming
+	ldx #0x1000
+	bset 00,x #0x10
+
 	;; enable the RTI
 	ldaa #0x40
 	staa 0x1024
@@ -12,25 +20,29 @@ _start:
 
 	;; set RTI intervals, and PA3/7 DDRs
 	ldaa #0x81
-	staa 0x1026
+	staa 0x1026  ;; RTI interval becomes E/2^14 = 6.6ms (or 150 Hz)
 
 	;; clear ADC register
 	clra
 	staa 0x1030
 
 	;; set the stack pointer
-	lds _stack
+	lds #_stack
 
 	;; blank initialised variables - should match memory.x's page0
 	ldx #0x0000
 loop1:
-	cpx #0x0080
+	cpx #0x0100
 	bcc out1
 	clr 00,x
 	inx
 	bra loop1
 out1:
 
+	;; stop chiming
+	ldx #0x1000
+	bclr 00,x #0x10
+
 	jsr main
 
 infinity: