diff --git a/pymlac/TTD.txt b/pymlac/TTD.txt
new file mode 100644
index 0000000..a0c2e34
--- /dev/null
+++ b/pymlac/TTD.txt
@@ -0,0 +1,4 @@
+Maybe decode instructions into LAC and ILAC (for example).  That is, don't
+decode instruction bit - include it in the opcode.  The code for LAC and ILAC
+will be almost identical except for extra indirect code.
+