diff --git a/sim/src/pdump.rs b/sim/src/pdump.rs
new file mode 100644
index 0000000..dbb42d5
--- /dev/null
+++ b/sim/src/pdump.rs
@@ -0,0 +1,76 @@
+// Printable hexdump.
+
+pub trait HexDump {
+    // Output the data value in hex.
+    fn dump(&self);
+}
+
+struct Dumper {
+    hex: String,
+    ascii: String,
+    count: usize,
+    total_count: usize,
+}
+
+impl Dumper {
+    fn new() -> Dumper {
+        Dumper {
+            hex: String::with_capacity(49),
+            ascii: String::with_capacity(16),
+            count: 0,
+            total_count: 0,
+        }
+    }
+
+    fn add_byte(&mut self, ch: u8) {
+        if self.count == 16 {
+            self.ship();
+        }
+        if self.count == 8 {
+            self.hex.push(' ');
+        }
+        self.hex.push_str(&format!(" {:02x}", ch)[..]);
+        self.ascii.push(if ch >= ' ' as u8 && ch <= '~' as u8 {
+            ch as char
+        } else {
+            '.'
+        });
+        self.count += 1;
+    }
+
+    fn ship(&mut self) {
+        if self.count == 0 {
+            return;
+        }
+
+        println!("{:06x} {:-49} |{}|", self.total_count, self.hex, self.ascii);
+
+        self.hex.clear();
+        self.ascii.clear();
+        self.total_count += 16;
+        self.count = 0;
+    }
+}
+
+impl<'a> HexDump for &'a [u8] {
+    fn dump(&self) {
+        let mut dump = Dumper::new();
+        for ch in self.iter() {
+            dump.add_byte(*ch);
+        }
+        dump.ship();
+    }
+}
+
+impl HexDump for Vec<u8> {
+    fn dump(&self) {
+        (&self[..]).dump()
+    }
+}
+
+#[test]
+fn samples() {
+    "Hello".as_bytes().dump();
+    "This is a much longer string".as_bytes().dump();
+    "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f".as_bytes().dump();
+}