Back in the archives there is another post on this same problem. My venerable -15C did the exact same thing this past week after I replaced its very dead batteries. No amount of button-pushing tricks would clear it. The USER flag remained on even when f USER was pressed and the top row function keys were operating in the inverted condition, per the USER function. Even ON y^x had no effect.

Removing the batteries initially did not work, and I noticed the memory stayed up even with the batteries out ten minutes or so. This little CMOS wonder is amazingly robust with no power. However, removing the batteries overnight did clear the fault.

I could not work up the courage to try the paper-clip shorting of the batteries suggested in the Users Manual.

I'm glad to have my personal copy of the finest pocket calulator ever built back in perfect operating condition.

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I'm glad to have my personal copy of the finest pocket calulator ever built back in perfect operating condition.

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You are now obviously talking about the HP 42S. :-)

My basis for comparison is Brand X (no RPN), my HP-35, my HP-67, and my HP-48GX. I still have the first two, but rarely dig them out as their batteries are history. I gave the -48GX away (I bought it when I thought I'd lost the -15C, and by the time I got it I used a computer for the fancy stuff).

The 15C, OTOH, runs for years on three button cells, programs like my -67, and always makes me smile.

I never had a -42S, but I can understand why you would like it ... many similar charms.

Funny, the Hp-80 has now such "USER" mode :-))