TI-H: Re: SPinTerface & Turbo/C9 solution for 85???

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TI-H: Re: SPinTerface & Turbo/C9 solution for 85???



>To: richfiles@hotmail.com
>Subject: questions
>From: justin.bosch%tfexchng@min.net (JUSTIN BOSCH)
>Date: Thu, 14 Aug 97 01:05:00 -0500
>
>I was wondering what exactly happens when you install a turbo switch 
and
>how much does it cost if I get it with a SPinTerface?  Is there some
>kind of waiting list or anything?


I charge $20 for SPinTerface instalation and will do the turbo with the 
instalation for free ($15 for separate turbo install, cause postage, 
when combined makes turbo so cheap).

There are two types of clocks: crystal occilator based clocks and RC, 
or, resistor Capacitor clocks. The TI uses an RC clock cause if you drop 
the calc, a crystal in a crystal clock can break. When electricity goes 
through an RC circuit, it resonates, or goes back and forth. The values 
of the resistor and capacitor change the frequency the electricity 
cycles. If you reduce the capacitance, the frequency will increase, and 
if the frequency increases, he clock rate is increased, making the 
processor cycle, or run faster. The reason for the limits on some of 
these parts (calc crashes if it's too low) is cause the resonate 
frequency is too far from the natural resonance frequency. If you 
changed both the resistor and the capacitor in pairs, it might be 
possible to achieve even higher frequencies because the resistor and 
capacitor, both changed, would still match, making the whole natural 
resonance frequency higher, making it, posibly, more stable!!!

Right now, only the capacitor is changed. This makes it not as stable as 
it ought to be, but much, much faster. The values have been "toyed" with 
or calculated till a safe frequency was found. The TI-85's natural 
resonate frequency limit is probably so close to the capacitance of the 
pads and traces and chips, that some calcs can make it passed and keep 
going while others lose the resonate frequency, losing the clock cycle 
and crashing.

I have another theory on the C9 problem. One calc that I turboed didn't 
work with C9 removed, so I soldered it back in. It still didn't work. I 
remembered a few messages describing the same problem. I looked at the 
removed capacitor, with a hunch and saw a piece of the circuit boards 
copper wire trace torn off, stuck still to the capacitor. I examined th 
board, and sure enough, it was torn. There was still exposed copper on 
the wire leading to the processor, but it still didn't work. I was 
thinking "Sh*t, I just screwed up my calc!", but I remembered a music 
synthesizer I fixed years back. The board was cracked in two and I had 
run wire between each broken trace. I examined it and found that the 
pain that showed the parts placement covered a trace, making it 
completely invisible, so I scratched off the paint and soldered it. The 
sythesizer still works to this day! I knew the calc used an RC circuit, 
but ther was no wire to the resistor, I scratched the paint offthe left 
side of C9 that marked it's location and sure enough, There was the 
missing trace! I soldered it and my calc ran Purr-fect!!!  (=

It's very well possible that sometimes the pads get too hot and break 
away with the capacitor. If you leave the cap out, the resistor isn't 
connected, and the resistor isn't part of the RC circuit anymore, even 
if the capacitor is the wires and internal capacitance of the chip. That 
results in a "fatal" crash. If when you resolder it, you still can't get 
it to work, you are probably only getting the trace on the proccessor 
side of the circuit soldered. The white paint prevents the solder from 
even getting near the trace leading to the resistor. I know this is true 
because it happend to ME!!!

Those are my two bits on the turbo and how it works and why C9 removal 
doesn't always work and why some calcs don't like low capacitances, and, 
and, and.......

I hope this is of major use to someone???

Also, can some one check out the idea of changing the resistor and 
capacitor as a pair on calcs like the 82. The capacitor can't go below 
5pf and I think that this resonate frequency stuff may be the reason. If 
someone could get a physics book and look up the equation for resonate 
frequency in RC circuits (I tossed my notes), It might even be possible 
to come up with a true "ultimate turbo"!!!

My brain needs a rest now, I think I hurt it...   (;



Richard Piotter



e-mail: richfiles@hotmail.com



home page: <A 
HREF="http://www.geocities.com/SiliconValley/Lakes/5081/Richfiles.html">The 
Richfiles</A>

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