The 5-pin DIN keyboard connector used with the first IBM PC (1981) and second-generation IBM AT (1984). It was subsequently replaced with the smaller 6-pin Mini-DIN connector on the IBM PS/2 in 1987.

That’s a standard DIN 6 layout of the physical pins, but with 3 “pairs” of signal lines. Very neatly done as well. My guess is for an “oomphy” motor.. like a spindle, NEMA42 servo, etc..