A92: Re:What is C11 in 92?


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A92: Re:What is C11 in 92?



I have just exchanged the chip capacitor C11 in my calculator top a 10 pF
chip capacitor and can confirm that TI-92 runs around 260% faster. The
circuit board of my calculator is significantly different from that at
Boris Lutz page where the speed-up procedure is described

http://cccsrv.trevano.ch/~blutz/TI92Spec/TIAccelerate.html

but C11 refers apparently still to the same component. Inverting a 10 by 10
random matrix using randmat(10,10)^-1 takes now 17 seconds in exact mode
(previously 45 s) and around 10 seconds in approximative mode (previously
26 s). The corresponding values for the unmodified TI 92II  (according to
Niklas Brunlid <nma95nbr@student1.lu.se>) are 32 seconds and 18 seconds.
The current consumption went up from 4.5 mA to 6.7 mA in the idle mode
(waiting for input) and from 26 mA to around 65 mA in the busy mode.  All
values (except on TI-92II) were measured at 5.1 V using four NiCd-batteries
and with newly reseted calculator. The parallell link together with PLINK!
program by Vincent Caron  caron@ec-lyon.fr, still works OK. I measured the
original chip capacitor to be 50 pF so the speed increase is not simply
inversely proportional to C11. This is probably explained by the internal
capacitance of the processors clock-circuit. According to  Boris Lutz page

http://cccsrv.trevano.ch/~blutz/TI92Spec/TISpUpFAQs.html

the minimum capacitance is around 8 pF for the TI-92 to work.

I have noticed large (50%) differences in current consumption with
different TI-92. There is also slight differences in speed. The above
values may therefore not apply to your own calculator.



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Dr. Richard Schatz
Royal Institute of Technology
Laboratory of Photonics and Microwave Eng.
KTH/ELE/FMI/ELECTRUM 229
S-164 40 Kista-Stockholm, SWEDEN

Phone: +46 8 752 1271
Fax:+46 8 752 1240
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