diff --git a/main.asm b/main.asm
index f183ab2..89dfd46 100644
--- a/main.asm
+++ b/main.asm
@@ -2,29 +2,52 @@
 
 prhex = $c174
 putchar = $c45e
+putstr = $c01b
 
 PUBLIC _main
 _main:
-    ld      hl,$0000
+    in      a,($81)
+    set     0,a
+    out     ($81),a
 
-main_loop:
-    ld      a,$0e
-    out     ($a0),a
-    ld      a,h
-    out     ($a1),a
-
-    ld      a,$0f
-    out     ($a0),a
-    ld      a,l
-    out     ($a1),a
-
-    call    delay
-    inc     hl
-    jp      main_loop
+    ld      a,($42)
+    ld      ($d0a0),a
 
     jp      ASMPC
 
 
+    ld      a,$40
+    ld      ($d77f),a
+
+    ld      hl,613
+main_loop:
+    push    hl
+    call    putstr
+    BYTE    "abc"
+    BYTE    "\0"
+    pop     hl
+    dec     hl
+    ld      a,l
+    or      h
+    jp      nz,main_loop
+
+back:
+    call    uart_rx
+    cp      $61
+    jp      z,log
+    ld      c,a
+    call    putchar
+    jp      back
+
+    jp      ASMPC
+
+log:
+    ld      a,($ffd5)
+    call    prhex
+    ld      a,($ffd4)
+    call    prhex
+    jp      back
+
 delay:
     push    de
     ld      de,$0000
@@ -35,4 +58,19 @@ delay_loop:
     jr      nz,delay_loop
 
     pop     de
-    ret
\ No newline at end of file
+    ret
+
+uart_rx:
+    in      a,($b1)
+    and     $01
+    jr      z,uart_rx
+    in      a,($b0)
+    ret
+
+uart_tx:
+    in      a,($b1)
+    and     $04
+    jr      z,uart_tx
+    ld      a,c
+    out     ($b0),a
+    ret