diff --git a/Lua/misc monitor.lua b/Lua/misc monitor.lua
new file mode 100644
index 0000000..fabe852
--- /dev/null
+++ b/Lua/misc monitor.lua	
@@ -0,0 +1,30 @@
+require "boilerplate"
+require "addrs.init"
+require "classes"
+require "messages"
+
+ByteMonitor = Class(Monitor)
+
+function ByteMonitor:mark(i, x, x1)
+    local now = emu.framecount()
+    local str = ('%02i=%02X (%s)'):format(i, x, self.name)
+    if not self.modified[i] then
+        self.modified[i] = {}
+    end
+    if not self.modified[i][x] then
+        self.modified[i][x] = true
+        self.dirty = true
+        str = str..' (NEW!)'
+    end
+    printf('%s  @%i', str, now)
+    message(str, 180)
+end
+
+local unk = ByteMonitor('unk', AL(0xF6, 0x37A))
+unk:load('data/_unk.lua')
+while mm do
+    unk:diff()
+    unk:save()
+    draw_messages()
+    emu.frameadvance()
+end