What IS this and who is Dave?

[Geoff Quickfall]

In the title.

I was working on three are card readers today and found this in the box with them. So of course I pulled it apart and inserted into a bare bones fullnut 41CX. I was given this at an HHC in the past but can't remember when, by whom and what it is/was.

Looks like a ram box with switching but plugging it in and the calc responds normally and doesn't recognize the unit in any catalog.

Changing the dip switches causes no effect or calculator freeze with a flashing display of nonsense characters.

So without furthe ado: