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hjalfi · (This post was last modified: 05-13-2024 10:16 PM by hjalfi.)

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. I also see that this is the same PCB (5180-1516) as the 15C, which is a two-chip calculator.

Which I find very interesting. There is an unpopulated footprint, presumably for the 1LH1 ROM for the 15C (although it's weird. Half the pins are either grounded or not connected). But there are also a lot of possibly unused pins on the CPU package itself.

Does anyone have the pinout for the 1LQ9? And the 1LH1 would be handy, too. I have vague ideas about building an external memory interface for this. It'd be fun to run Nut machine code programs for it...