Nixdorf LK-3000

I'm trying to find some info about the LK-3000, an early hand-held "computer". I think it was made by Nixdorf around 1979, but it was also sold under other labels (I think I've got a "Lexicon" labeled instance someplace). Can anybody tell me what modules were available? Was there a module that made the thing user programmable, for example? Is anybody aware of a pre-1979 programable handheld? I suppose something like the HP-65 is a candidate, but an alpha-numeric keyboard and display would be more compelling. Assuming the LK-3000 isn't user programmable, would anybody take offense at somebody calling it the first PDA? (No, I'm not selling one on eBay. There is one for sale there now -- it's overpriced, though. These things aren't exactly rare.) Thanks, Doug