🚀 go-pugleaf

In article <29E8BD78.9814@noiro.acs.uci.edu> gkwan@balboa.eng.uci.edu (Greg Kwan) writes:
>In article <1992Apr11.231955.1841@doug.cae.wisc.edu> kolstad@cae.wisc.edu (Joel Kolstad) writes:
>>I just remembered something... this watch had a BUG in it!  I remember that
>>I had found a key combination that would totally garble the time display.
>>If you hit the main fucntion button so it returned to "normal" display, it
>>would be fine again.  But when you hit just the right key combination to
>>start with, it would go through this bizarre pattern of garbage on the display
>>and eventually settle down into a garbage pattern that alternated on every
>>second.  Ha!  How many other people have discovered bugs in their wathces? :-)
>
>(raising my hand) I've encountered this.

This reminds me of my old Citizen Seven watch (with analog LC display).
It had a small lamp to lit the display when you push the correct button
(not too uncommon, no).  Instead of simply putting a switch in series
with the lamp some clever engineer had decided to run the signal through
the chip (btw, do they use microprocessors in watches or just some custom
logic IC's?).  There was a small delay of maybe 500 msec built in the IC
so if you pressed the light button for a short period of time the lamp
was turned on for 500 msec at least.

Well, everything worked just fine until the battery got somewhat
exhausted.  When you pressed the light button the lamp would turn on
 - and the batter voltage dropped much enough to stop the crystal-based
oscillator - which in turn stopped the 500 msec delay and left the lamp
turned on indefinitely.  Only when the voltage dropped below, say, 0.5V
would the transistor driving the lamp turn off.  After some time, the
oscillator would come up again and the watch was running until the next
time you occasionally pressed the light button... :-)

The later Citizen watches don't have this 'feature'.

  Jukka Marin

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