Nut 1LQ9 pinout?

[brouhaha]

(05-13-2024 10:15 PM)hjalfi Wrote:  I just picked up a 1994 Singaporean HP-12C from a local shop which sells things that people have lost on the train. It cost me five francs (== $5). Nice!

If I take the lid off, I can see the single chip which runs it, a Nut 1LQ9-0322. Looking around I can see that the two-chip version of this uses the 1LQ9-0325.

No 12C uses a 1LQ9-0325. That is ONLY used in the 15C. The 1LQ9-0325 contains half of the 15C ROM, with the other half in the 1LH1-0302.

The common PCB for 1LQ9 calculators has room for a 1LH1-0302 for the 15C, but the 1LQ9-0322 used in the 12C doesn't have the external bus interface. It is disabled either in the mask programming, or (possibly) by pin-strapping.

The 1LH1 pinout may be the same as the 1LE2, but I have not verified that.