This is a Hall effect keyboard produced in Hungary by TKI (Távközlési Kutató Intézet). The switches are RS 76 C switches, specifically an extremely rare form with a black plunger. The sole Hall sensor depicted is a Siemens SAS 251 S4 dual-output sink level model. The exact model number of the keyboard is not known; the code “NY6234” is simply taken from the markings on the PCB, as the case was not present.
The only indication of a manufacture date is on the single depicted sensor chip, which appears to have a date code of 8102 (week 2 1981). Presently SAS 251 S4 is not known before 1982, but this date is close enough to be legitimate according to present information.
The photos are archived from a now-deleted eBay auction listing 232635080738 “93 Rafi keys on PCB from Hungary Contactless alphanumeric Hall effect keyboard” from seller htlbcrf in Russia.