From f68a7a36c415b804c58f7ad2f88128c58ae06488 Mon Sep 17 00:00:00 2001
From: David Stancu <dstancu@nyu.edu>
Date: Sun, 4 Feb 2018 19:21:35 -0500
Subject: [PATCH] working single line with drop arrow key write

---
 src/main.S | 50 +++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 47 insertions(+), 3 deletions(-)

diff --git a/src/main.S b/src/main.S
index 6bc031b..a96b17c 100644
--- a/src/main.S
+++ b/src/main.S
@@ -36,13 +36,42 @@ inloop      clc
             bit   #%1
             bmi   keybranch
             jmp   inloop
-
 keybranch   jsr   keydown
             jmp   inloop
 
 keydown     nop
-            stal  $000400,X
-            ldal  $00C010
+            cmp   #$8B        ; up
+            beq   up
+            cmp   #$8A        ; down
+            beq   down
+            cmp   #$88        ; left
+            beq   left
+            cmp   #$95        ; right
+            beq   right
+            jmp   dispchar
+
+up          nop
+            jmp   rtsout
+down        nop
+            jmp   rtsout
+
+left        clc
+            cpx   #0
+            beq   rtsout
+            dex
+            jmp   rtsout
+
+right       clc
+            cpx   #39
+            beq   rtsout
+            inx
+            jmp   rtsout
+
+dispchar    stal  $000400,X
+            jmp   rtsout
+
+rtsout      ldal  $00C010
+            lda   #0
             rts
 
 ; working text blit
@@ -187,6 +216,21 @@ brkboi      brk
 
 
 
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