I think this part has been obsolete too long. The list that's on this website, derived from KEIL rather than the manufacturers, is pretty incomplete and quite out of date. Some of the parts listed are a nearly decade obsolete.

I've encountered some OTP versions of the part you mention, but since there's no ready way to verify that they've not been programmed, and since the sellers, being surplus hardware dealers, frequently lie, it's not worthwhile to pursue that type of part.

There is, of course, an upper limit to how much trouble I'm willing to go to in order to replace the very much aged hex keypad in question. I may just remove the MCU in the keypad and encode the keypad as-is, then translate its output with yet another MCU. I'm just trying to find the least painful way to deal with this problem.

Of course, the other side of the issue is the keycaps.

One thing at a time ...

RE