From 48a2749fd7e9b2bb46994dced281753940a2c935 Mon Sep 17 00:00:00 2001
From: Samuel Walker <swalker@piwalker.net>
Date: Fri, 21 Mar 2025 16:30:44 -0600
Subject: [PATCH] Created Variables in ZeroPage to reference addresses

---
 main.s | 58 +++++++++++++++++++++++++++++++---------------------------
 1 file changed, 31 insertions(+), 27 deletions(-)

diff --git a/main.s b/main.s
index 388186a..46ce8c6 100644
--- a/main.s
+++ b/main.s
@@ -11,6 +11,11 @@
 
 .segment "STARTUP"
 
+.segment "ZEROPAGE"
+InNum:    .res 1
+BCD:    .res 2
+TMP:    .res 1
+NUM:    .res 1
 .segment "CHARS"
 .incbin "./CHR-ROM.bin"
 
@@ -20,21 +25,21 @@ bg_pallets:
     .byte $0F, $30, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
 double_dabble:
     lda #0
-    sta $01
-    sta $02
+    sta BCD
+    sta BCD+1
     ldx #8
 dabble:
     ; check first digit
-    lda $01
+    lda BCD
     and #$F
     jsr check
-    sta $03
+    sta TMP
     lda #$F0
-    and $01
-    ora $03
-    sta $01
+    and BCD
+    ora TMP
+    sta BCD
     ; check second digit
-    lda $01
+    lda BCD
     and #$F0
     lsr
     lsr
@@ -45,26 +50,25 @@ dabble:
     asl
     asl
     asl
-    sta $03
+    sta TMP
     lda #$F
-    and $01
-    ora $03
-    sta $01
+    and BCD
+    ora TMP
+    sta BCD
     ; check third digit
-    lda $02
+    lda BCD+1
     and #$F
     jsr check
-    sta $03
+    sta TMP
     lda #$F0
-    and $02
-    ora $03
-    sta $02
+    and BCD+1
+    ora TMP
+    sta BCD+1
     ; Shift
     clc
-    rol $00
-    rol $01
-    rol $02
-    lda $00
+    rol InNum
+    rol BCD
+    rol BCD+1
     dex
     bne dabble
     rts
@@ -129,22 +133,22 @@ forever:
     jmp forever
 
 nmi:
-    inc $05
-    lda $05
-    sta $00
+    inc NUM
+    lda NUM
+    sta InNum
     jsr double_dabble
     lda $2002
     lda #$20
     sta $2006
     lda #$20
     sta $2006
-    lda $02
+    lda BCD+1
     and #$F
     cmp #0
     bne :+
     lda #10
 :   sta $2007
-    lda $01
+    lda BCD
     and #$F0
     lsr
     lsr
@@ -154,7 +158,7 @@ nmi:
     bne :+
     lda #10
 :   sta $2007
-    lda $01
+    lda BCD
     and #$F
     cmp #0
     bne :+