diff --git a/Makefile b/Makefile
index 7eacd99..28b788c 100644
--- a/Makefile
+++ b/Makefile
@@ -4,6 +4,7 @@ SRC = \
 	  src/ceda_print_a.asm	\
 	  src/ceda_print_c.c	\
 	  src/main.c 			\
+	  src/io_a.c            \
 	  \
 
 OBJ = $(patsubst %, %.o, $(basename $(SRC)))
diff --git a/src/io.h b/src/io.h
new file mode 100644
index 0000000..f376d38
--- /dev/null
+++ b/src/io.h
@@ -0,0 +1,10 @@
+#ifndef CEDA_IO_H
+#define CEDA_IO_H
+
+#include <stdint.h>
+
+void io_out(uint8_t address, uint8_t value);
+
+uint8_t io_in(uint8_t address);
+
+#endif // CEDA_IO_H
diff --git a/src/io_a.asm b/src/io_a.asm
new file mode 100644
index 0000000..dcf2f82
--- /dev/null
+++ b/src/io_a.asm
@@ -0,0 +1,18 @@
+SECTION code
+PUBLIC _io_out
+
+_io_out:
+    push    ix
+    ld      ix,$0000
+    add     ix,sp
+
+    push bc
+
+    ld      c,(ix+$04)
+    ld      b,(ix+$05)
+    out     (c),b
+
+    pop     bc
+
+    pop ix
+    ret
diff --git a/src/main.c b/src/main.c
index 66c64de..699bde2 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,4 +1,5 @@
 #include "ceda_print.h"
+#include "io.h"
 
 int globalvar = 0x7777;
 
@@ -6,5 +7,8 @@ int main(void) {
     ceda_print("Hello world!");
     ceda_cls();
 
+    io_out(0x81, 0x80);
+    ceda_print("ABCD");
+
     return 0;
 }