My favorite uncle, now in his 90s, hangs on to an old 386 PC running DOS even after I bought him a new PC.  He uses both.  But he has also hung on to old keyboards he loves, including a pair of keyboards so old that they have the old PC/AT style keyboard connector.  He wanted to use one of them with his new PC that has USB inputs only (I had previously bought him a PS/2 keyboard to USB adapter so he could use his *other* beloved, only slightly newer, keyboard.)  He called me asking if I could find a way to get his old "big round plug" keyboard with the new PC.