Re: More ROM dumping Message #10 Posted by Ken Sumrall on 26 Jan 2004, 5:14 p.m., in response to message #9 by Eric Smith
Eric Smith wrote:
He got the instructions from the Internet, of course. I haven't looked for it. I imagine it's done by reducing the value of the capacitor in the LC oscillator, as on most other HPs.
I'll ask him if he has a pointer to the info.
Ken Sumrall replies:
Actually, I figured it out myself. Years ago, when I was
in college, someone wrote in to PPC Journal and offered to
triple the speed of anyone's Voyager calculator if you sent
it and $25 to Hong Kong. I was not about to send my new
HP-16C (I won it when the Michigan State Programming team
came in first at the regional competition!) to Hong Kong,
but decided I should be able to figure it out myself. I
popped mine open, and saw the oscillator parts,
but mistakenly thought I saw a cap and a resistor. Thus, at
the time, my efforts to speed it up were in vain.
However, after college, I joined HP, and e-mailed an
engineer still in the calc division in Corvallis, and
learned it was an inductor, not a resistor (duh) on the board, and the rest was just some experimentation at HP's
lab stock room. Just add another inductor in parallel
with the original, and bingo, it goes faster.
Of course, this probably reduces the temperature operating
margins of the device, but I tend to do my hacking in an
air conditioned/heated office/house, so I didn't care.
Also, the device is probably less tolerant of low batteries,
but again, they last so long anyhow, I don't care if I have
to replace them as soon as the low batt indicator comes on.
I've sent all my notes on this speedup to Eric, and if he
doesn't post them here in a day or two, I'll post them
myself.
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