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HP48 Keyboard Scanning and Electrical Resistance



#4

The keyboard of the HP48 is scanned as somewhat documented in the available schematics.

Can anyone explain (or direct me to the appropriate links) why the keyboard contact paths have a significant (kilohms) electrical resistance?

Regards,
TomCee


#5

Documented in US Patent 5,065,356.

You'll find a copy posted on Eric's site here: PDF of HP Patent 5,065,356


#6

Randy:
Excellent resource! Thank you very much!
TomC


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