HP 15C CE key bounce

[borjam]

I really don't understand why this is possible in the first place.

I own an original HP-16C manufactured in 1984 (USA). I got it on eBay years ago and all the keys work perfectly. Only the logo badge is missing. Its sleeve is in perfect condition.

When the HP-15C Limited Edition came out I got two. Both had bounces. I kept one of them, haven't used it in a while. Some keys bounce and "9" either doesn't register or it bounces. And the sleeve is disintegrating.

A friend presented me last week with a brand new HP-15C CE last week. Sometimes I see a key bounce but seems to be better.

I wonder whether the original Voyagers relied on software and hardware to prevent bounces and the fast processor has rendered the software solution useless(?).


Has someone somehow patched the firmware in order to prevent bounce? The two classic Voyagers I own definitely show some lag between a key press and the symbol being displayed on screen. That might suggest a simple software solution to key bounce. Not to keys not registering of course.

Other HP calculators I own:

- HP-10C from 1982 (USA). A gift from a friend who used it back in the day in college. Keys work perfectly. Case in very good condition except for an internal cloth layer that went loose.

- Last version HP-32Sii (Indonesia). No bounces, perfect keyboard. Perfect case.

- HP-49G I haven't used for a long while. Unusable keyboard, some keys need to be actually hammered.

- HP35S (China): Keys work. Exterior of the case nearly decomposed, became sticky.

- Old and battered HP-41CV (1985), I don't have batteries to test it right now but the last time I used it it worked perfectly despite some battery contacts damage. I got it on eBay years ago.