MOS6520 looking mostly there.

core/src/periph/mos6520/bus_device.rs

@@ -0,0 +1,26 @@
+use crate::periph::mos6520::Mos6520;
+use crate::traits::bus_device::BusDevice;
+
+impl BusDevice for Mos6520 {
+    fn min_offset(&self) -> u16 {
+        self.offset
+    }
+
+    fn max_offset(&self) -> u16 { self.max_offset }
+
+    fn address_bus(&self) -> u16 {
+        self.address_bus
+    }
+
+    fn data_bus(&self) -> u8 {
+        self.data_bus
+    }
+
+    fn set_address_bus(&mut self, new_value: u16) {
+        self.address_bus = new_value
+    }
+
+    fn set_data_bus(&mut self, new_value: u8) {
+        self.data_bus = new_value
+    }
+}