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comp.sys.palmtops HP100LX Frequently Asked Questions
Section - 16. Double-speed crystals

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Q: What is the "double-speed crystal technique?"
A: It is a hardware-modification technique which makes a 100/200LX
faster by swapping crystal oscillator with a faster (usually
double-speed) crystal. It requires:

	- faster crystal
	- soldering tools
	- torx screwdriver
	- And most importantly your courage and soldering skills

WARNING: Do this at your own risk!

Q: If I swap the crystal, what happen to my warranty?

A: Doing this will void your wararanty.  If you are well-trained in
soldering, you can replace the original crystal before sending it to a
service center.  Of course they may notice the difference in solder,
and then your warranty will become void.

Q: What happens if I replace the crystal?
A: Short answer: Your palmtop will run faster!

Long answer:

There are many troubles that arise with the speed-up.  The speedup
will cause the clock will go faster and serial communication port will
not be able to sync to other machines, Also, if you use 100%-faster
crystal, the LCD screen will become unreadable, or some noise will
appear on the screen, and battery voltage detection go unstable.

In order to fix these problems, you will need a software driver to
tailor your palmtop to the new frequency rate.  There are several
drivers available on the Internet.  Here are rough description for
those drivers.  For details, refer to document comes with the drivers:

	- turbo.zip (by Robert S.Williams, on eddie.mit.edu and other places)
	  Fixes: clockspeed
	  Problems remaining: LCD/battery voltage
		This program is not made to avoid the problems listed above.
		Why does it work?  It is almost coincidence.
	- clockup.sys (by Jun-ichiro Itoh, on ftp.csl.sony.co.jp)
	  Fixes: clockspeed/LCD
	  Problems remaining: battery voltage
	  URL: ftp://ftp.csl.sony.co.jp/pub/HPLX/misc/
		It supports crystals with non-exact frequency too. (see below)
	- clkup31m.sys (by K.Terasaki & K.Mitsuya)
	  Fixes: clockspeed/LCD/battery voltage
	  Problems remaining: (maybe nothing)
		The required driver is product of NIFTY-Serve (CI$ in Japan)
		FMODEM forum, and they are sold in Japan, or can be downloaded
		from FMODEM forum.  It seems that it is NOT a free software.
		It is now exported to Germany and some other countries,
		reportedly.

There are also application-specific troubles that arise related to
timing.  For example, you cannot use REMCOM data (learning
remote-control software) that was recorded on a vanilla 100/200LX.
Speeded-up palmtops will need to learn the remote-control signal by
themselves.  Also, TT.EXE, a program for generating DTMF tone with the
internal speaker, will generate incorrect tones. (because it generates
a sinewave by doing loops, instead of using timer chips)

NOTE: The above mentioned crystals should oscillate with "fundamental
mode", i.e. at exact frequencies mentioned above.  Usually crystals
made for above 20 or 30MHz operate with "3rd overtone mode" and those
crystals won't make your HPLX any faster.  It is highly likely that
you'd end up with a slower unit at about 2/3 of the original speed.
So, never try to use such crystals for replacement.

Q: What kind of crystal should I use?
A:The Hornet chip, which controls the low-level hardware of 100/200LX,
allows some specific CPU clock speeds only:
	10.738636MHz	15.836773MHz	21.477272MHz	31.673550MHz
The original crystal of 100/200LX is 15.836773MHz, therefore you
should use a 21.477272MHz(35% speedup) or 31.673550MHz (100% speedup)
crystal.

Unfortunately, these frequencies are not very common for ready-made
crystals.  Also, the crystal must fit into a very small space inside
your palmtop.  Therefore, you should order a special crystal unit with
a small case and one of the above frequencies.

Reportedly a small tolerance in frequency seems acceptable, but causes
some small problems with the clock speed.  A report says that the
clock will go 1% faster with 32.000MHz crystal, though this will be
corrected when you shut palmtop's the power off.  32.000MHz is 102%
speedup, therefore there's 1% tolerance in a double-speed
crystal. (32.000000/31.673550 = 1.01) Reportedly there are some
ready-made crystals fit into a 100/200LX, that have a 32.000MHz
frequency.

Q: Where can I purchase a faster crystal for my 100/200LX?

A: No answer is provided in this document.  See above.  Your local parts
shop may have an appropriate ready-made crystal for your palmtop.

Q: What happens to the battery life if I use faster crystal?

Your battery life will be shortened, but many people report this as
being a negligible difference.


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Top Document: comp.sys.palmtops HP100LX Frequently Asked Questions
Previous Document: 15. Obscure undocumented tips, tricks, and trivia
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