Add basic terminal card

src/main.rs

@@ -8,6 +8,7 @@ mod m68k;
 mod ram;
 mod rom;
 mod storage;
+mod term;
 use crate::{
     backplane::Backplane,
     m68k::{BusError, M68K},

src/term.rs

@@ -0,0 +1,40 @@
+use std::fmt::Display;
+
+use nullable_result::NullableResult;
+use serde_yaml::Mapping;
+
+use crate::{card::Card, m68k::BusError, register};
+
+#[derive(Debug)]
+pub struct Term;
+
+impl Display for Term {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("Terminal card")
+    }
+}
+
+impl Card for Term {
+    fn new(_data: &Mapping) -> Self
+    where
+        Self: Sized,
+    {
+        Self
+    }
+
+    fn read_byte_io(&mut self, address: u8) -> NullableResult<u8, BusError> {
+        match address {
+            0xFF => NullableResult::Ok(3),
+            _ => NullableResult::Null,
+        }
+    }
+
+    fn write_byte_io(&mut self, address: u8, data: u8) -> NullableResult<(), BusError> {
+        if address == 0 {
+            print!("{}", data as char);
+        }
+        NullableResult::Ok(())
+    }
+}
+
+register!(Term, "term");