FS: MPU 401 breakout box

[ratfink]

I bought one of these a while ago without realising I needed an interface card.  I've seen Great Hierophant's pages showing a schematic for the card but to be honest I don't think I will ever get round to making one, so the breakout box is up for grabs if anyone wants to make me a reasonable offer.  Externally in very good condition.  Obviously I've no idea of it works as I  don't have the interface .  It's marked Roland DG MPU-401.

[Cloudschatze]

I'm still looking to acquire a unit with ROM v1.2, which would only be present in a "DG" release. What is the serial number?

[ratfink]

Unfortunately it's faded and smudged, but using a magnifying glass shows the serial number is 4-something-0398, probably 420398.  That's on a label stuck on the underside.  

I took the lid off but I'm none the wiser.  There's a socketed chip with a label that's stuck on a raised portion.  Label says mpu 401 and then a series of numbers 1 2 3 4 5 6 etc.  Seems to be a pink dot on the 2.