I thought it was a Tandberg Data at first - Cherry made some for Tandberg with caps like that, numbered G84-9021 in their model number system, but I think that's the one in u/kanyesutra's comment. Looks like the caps could have been a standard design, perhaps, rather like the DIN standard in (West) Germany.

If it's really made in 1980, it could have some quite rare old switches. I think there are some RAFI or Siemens keyboards with that cap style. But chances of finding a non-intrusive converter are small - if you want to use it you might have to map the matrix and fit a new controller. You might try HaaTa's Kiibohd converters first, just in case he did one for your board.