diff --git a/src/main.rs b/src/main.rs
index c2f4f46..bcb63ea 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,5 @@
 use anyhow::{Result, anyhow};
-use macroquad::prelude::*;
+use macroquad::color::*;
 use serialport::SerialPortType;
 
 #[derive(Clone, Copy, Debug)]
@@ -12,7 +12,6 @@ pub enum Instruction {
 
 pub struct SerialDevice {
     port: Box<dyn serialport::SerialPort>,
-    ready: bool,
 }
 
 const CHANNEL_COUNT: u8 = 4;
@@ -26,18 +25,16 @@ impl SerialDevice {
                 SerialPortType::UsbPort(_) => {
                     this = Ok(Self {
                         port: serialport::new(port.port_name, 115200).open()?,
-                        ready: true,
                     });
+                    break;
                 }
                 _ => {}
             };
-            break;
         }
         this
     }
 
     fn note_off(&mut self, ch: u8) -> Result<()> {
-        assert!(self.ready);
         assert!((0..CHANNEL_COUNT).contains(&ch));
         let bytes: Vec<u8> = vec![0x80 + ch];
         self.port.write(&bytes)?;
@@ -45,7 +42,6 @@ impl SerialDevice {
     }
 
     fn note_on(&mut self, ch: u8, note: u8) -> Result<()> {
-        assert!(self.ready);
         assert!((0..CHANNEL_COUNT).contains(&ch));
         assert!((0..=127).contains(&note));
         let bytes: Vec<u8> = vec![0x90 + ch, note];
@@ -54,19 +50,16 @@ impl SerialDevice {
     }
 
     fn modulation(&mut self, ch: u8, depth: u8, rate: u8) -> Result<()> {
-        assert!(self.ready);
         assert!((0..CHANNEL_COUNT).contains(&ch));
         assert!((0..=127).contains(&depth));
-        assert!((0..=255).contains(&rate));
         let bytes: Vec<u8> = vec![0xA0 + ch, depth, rate];
         self.port.write(&bytes)?;
         Ok(())
     }
 
     fn frequency_on(&mut self, ch: u8, freq: u16) -> Result<()> {
-        assert!(self.ready);
         assert!((0..CHANNEL_COUNT).contains(&ch));
-        let bytes: Vec<u8> = vec![0xB0 + ch, (freq & 0xff) as u8, (freq & 0xff00 >> 8) as u8];
+        let bytes: Vec<u8> = vec![0xB0 + ch, (freq & 0xff) as u8, (freq >> 8) as u8];
         self.port.write(&bytes)?;
         Ok(())
     }
@@ -87,28 +80,55 @@ impl SerialDevice {
     }
 }
 
-const INSTRUCTIONS_PATTERN: usize = 1024;
-
 pub struct Pattern {
-    pub channels: [[Option<Instruction>; INSTRUCTIONS_PATTERN]; CHANNEL_COUNT as usize],
+    pub rows: Vec<[Option<Instruction>; CHANNEL_COUNT as usize]>,
 }
 
 impl Pattern {
     pub fn new() -> Self {
+        let mut rows = Vec::new();
+        rows.resize_with(256, || [None; CHANNEL_COUNT as usize]);
+        Self { rows }
+    }
+}
+
+pub struct TimeSignature {
+    pub numerator: u8,
+    pub denominator: u8,
+}
+
+impl Default for TimeSignature {
+    fn default() -> Self {
         Self {
-            channels: [[None; INSTRUCTIONS_PATTERN]; CHANNEL_COUNT as usize],
+            numerator: 4,
+            denominator: 4,
         }
     }
 }
 
 pub struct Song {
+    pub bpm: f64,
+    pub time_signature: TimeSignature,
     pub patterns: Vec<Pattern>,
     pub pattern_order: Vec<usize>, // index into patterns
 }
 
 impl Song {
-    pub fn new() -> Self {
+    const DEFAULT_BPM: f64 = 120.0;
+
+    pub fn new(bpm: Option<f64>, time_signature: Option<TimeSignature>) -> Self {
         Self {
+            bpm: bpm.unwrap_or(Self::DEFAULT_BPM),
+            time_signature: time_signature.unwrap_or_default(),
+            patterns: vec![Pattern::new()],
+            pattern_order: vec![0],
+        }
+    }
+
+    pub fn empty(bpm: Option<f64>, time_signature: Option<TimeSignature>) -> Self {
+        Self {
+            bpm: bpm.unwrap_or(Self::DEFAULT_BPM),
+            time_signature: time_signature.unwrap_or_default(),
             patterns: Vec::new(),
             pattern_order: Vec::new(),
         }
@@ -130,14 +150,20 @@ impl App {
     }
 
     async fn update(&self) {
-        clear_background(RED);
+        macroquad::window::clear_background(WHITE);
 
-        draw_line(40.0, 40.0, 100.0, 200.0, 15.0, BLUE);
-        draw_rectangle(screen_width() / 2.0 - 60.0, 100.0, 120.0, 60.0, GREEN);
+        macroquad::shapes::draw_line(40.0, 40.0, 100.0, 200.0, 15.0, BLUE);
+        macroquad::shapes::draw_rectangle(
+            macroquad::window::screen_width() / 2.0 - 60.0,
+            100.0,
+            120.0,
+            60.0,
+            GREEN,
+        );
 
-        draw_text("Hello, Macroquad!", 20.0, 20.0, 30.0, DARKGRAY);
+        macroquad::text::draw_text("Hello, Macroquad!", 20.0, 20.0, 30.0, DARKGRAY);
 
-        next_frame().await
+        macroquad::window::next_frame().await
     }
 }