Adapted Cherry UB80-01AA
The images below depict a Cherry UB80-01AA Cherry-made Hi-Tek High Profile keyboard; they were archived in 2018 from the now-deleted eBay listing 122203538782 “Cherry Computer Keyboard UB80-01AA Digital 249945 & More Rare” from seller toy_collector72. The Cherry serial number is 59067 and the Digital serial number is 249945. From the IC dates, the unit was manufactured around 1979. This example uses an SMC KR3600-902 encoder.
This particular unit has been connected to some kind of adapter board featuring a TR1402A Universal Asynchronous Receiver/Transmitter (UART).