feat: implement more registers

src/high_ram.rs

@@ -0,0 +1,22 @@
+#[derive(Debug, Clone)]
+pub struct HighRAM {
+    buf: Box<[u8]>,
+}
+
+impl Default for HighRAM {
+    fn default() -> Self {
+        Self {
+            buf: vec![0u8; 127].into_boxed_slice(),
+        }
+    }
+}
+
+impl HighRAM {
+    pub fn write_byte(&mut self, index: usize, byte: u8) {
+        self.buf[index] = byte;
+    }
+
+    pub fn read_byte(&self, index: usize) -> u8 {
+        self.buf[index]
+    }
+}