HP-33E Missing Pin on Memory Chip

[teenix]

I have one of these chips with the silver paint faded a bit and can almost see what looks like a standard serial number on it like xMxx-x00x. I cannot make out the x's.

As the power pin is not connected, it seems a waste of an expensive IC if these are actual unused ROMs.

I tried measuring the pins with an ohmmeter, but all read open circuit, same as normal ROMs.

I thought maybe they balance the pressure on the pins of the other ROM IC's on the padded circuit film, but these IC's appear on soldered versions as well.

Weird.

cheers

Tony