diff --git a/lwcpu/src/lib.rs b/lwcpu/src/lib.rs
index 2c89c5c..62fbdcb 100644
--- a/lwcpu/src/lib.rs
+++ b/lwcpu/src/lib.rs
@@ -4,26 +4,24 @@ use core::ptr::{read_volatile, write_volatile};
 
 const BASE_POINTER: u32 = 0x2000_0000;
 
-const NUMBER_DISPLAY_OFFSET : u32 = 0x00;
-const RANDOM_NUMBER_OFFSET  : u32 = 0x04;
-const BUTTONS_OFFSET        : u32 = 0x08;
-const TEXT_DISPLAY_OFFSET   : u32 = 0x0C;
-const KEYBOARD_OFFSET       : u32 = 0x10;
-const SCREEN_OFFSET         : u32 = 0x80;
-
-const NUMBER_DISPLAY_POINTER : *mut u32 = (BASE_POINTER + NUMBER_DISPLAY_OFFSET) as *mut u32;
-const RANDOM_NUMBER_POINTER  : *mut u32 = (BASE_POINTER + RANDOM_NUMBER_OFFSET)  as *mut u32;
-const BUTTONS_POINTER        : *mut u8  = (BASE_POINTER + BUTTONS_OFFSET)        as *mut u8;
-const TEXT_DISPLAY_POINTER   : *mut u8  = (BASE_POINTER + TEXT_DISPLAY_OFFSET)   as *mut u8;
-const KEYBOARD_POINTER       : *mut u32 = (BASE_POINTER + KEYBOARD_OFFSET)       as *mut u32;
-const SCREEN_POINTER         : *mut u32 = (BASE_POINTER + SCREEN_OFFSET)         as *mut u32;
+const NUMBER_DISPLAY_OFFSET: u32 = 0x00;
+const RANDOM_NUMBER_OFFSET: u32 = 0x04;
+const BUTTONS_OFFSET: u32 = 0x08;
+const TEXT_DISPLAY_OFFSET: u32 = 0x0C;
+const KEYBOARD_OFFSET: u32 = 0x10;
+const SCREEN_OFFSET: u32 = 0x80;
 
+const NUMBER_DISPLAY_POINTER: *mut u32 = (BASE_POINTER + NUMBER_DISPLAY_OFFSET) as *mut u32;
+const RANDOM_NUMBER_POINTER: *mut u32 = (BASE_POINTER + RANDOM_NUMBER_OFFSET) as *mut u32;
+const BUTTONS_POINTER: *mut u8 = (BASE_POINTER + BUTTONS_OFFSET) as *mut u8;
+const TEXT_DISPLAY_POINTER: *mut u8 = (BASE_POINTER + TEXT_DISPLAY_OFFSET) as *mut u8;
+const KEYBOARD_POINTER: *mut u32 = (BASE_POINTER + KEYBOARD_OFFSET) as *mut u32;
+const SCREEN_POINTER: *mut u32 = (BASE_POINTER + SCREEN_OFFSET) as *mut u32;
 
 pub struct Screen {}
 impl Screen {
     #[inline]
-    pub fn clear() {
-    }
+    pub fn clear() {}
     #[inline]
     pub fn turn_pixel_on(x: u8, y: u8) {
         unsafe {
@@ -57,6 +55,17 @@ impl TextDisplay {
         }
     }
 }
+impl core::fmt::Write for TextDisplay {
+    #[inline]
+    fn write_str(&mut self, s: &str) -> core::fmt::Result {
+        for ch in s.bytes() {
+            unsafe {
+                write_volatile(TEXT_DISPLAY_POINTER, ch);
+            }
+        }
+        return Ok(());
+    }
+}
 
 pub struct NumberDisplay {}
 impl NumberDisplay {
@@ -83,13 +92,13 @@ impl RNG {
 pub struct Buttons {}
 impl Buttons {
     pub const RIGHT_RIGHT: u8 = 0b00000001;
-    pub const RIGHT_DOWN : u8 = 0b00000010;
-    pub const RIGHT_LEFT : u8 = 0b00000100;
-    pub const RIGHT_UP   : u8 = 0b00001000;
-    pub const LEFT_RIGHT : u8 = 0b00010000;
-    pub const LEFT_DOWN  : u8 = 0b00100000;
-    pub const LEFT_LEFT  : u8 = 0b01000000;
-    pub const LEFT_UP    : u8 = 0b10000000;
+    pub const RIGHT_DOWN: u8 = 0b00000010;
+    pub const RIGHT_LEFT: u8 = 0b00000100;
+    pub const RIGHT_UP: u8 = 0b00001000;
+    pub const LEFT_RIGHT: u8 = 0b00010000;
+    pub const LEFT_DOWN: u8 = 0b00100000;
+    pub const LEFT_LEFT: u8 = 0b01000000;
+    pub const LEFT_UP: u8 = 0b10000000;
 
     #[inline]
     pub fn read() -> u8 {
diff --git a/test/src/main.rs b/test/src/main.rs
index c5e2dbf..a0a0a43 100644
--- a/test/src/main.rs
+++ b/test/src/main.rs
@@ -1,8 +1,8 @@
 #![no_std]
 #![no_main]
 
-use core::panic::PanicInfo;
-use lwcpu::{self, NumberDisplay, Screen, TextDisplay};
+use core::{fmt::Write, panic::PanicInfo};
+use lwcpu::{NumberDisplay, Screen, TextDisplay};
 use riscv_rt::entry;
 
 #[panic_handler]
@@ -11,16 +11,15 @@ fn panic_handler(_info: &PanicInfo) -> ! {
     loop {}
 }
 
-const HELLO_WORLD: &[u8; 13] = b" Hello world!";
+const HELLO_WORLD: &str = " Hello world!";
 
 #[entry]
 fn main() -> ! {
+    let mut text = TextDisplay{};
     for i in 0..31 {
         Screen::set_line(i, 1 << i);
     }
     loop {
-        for ch in HELLO_WORLD {
-            TextDisplay::put_char(*ch);
-        }
+        let _ = text.write_str(HELLO_WORLD);
     }
 }