Overclocking Calculators?

Klar writes "If you're looking for something new to prove your tech prowess, Richard Piotter has a great how to on overclocking Texas Instruments graphing calculators. You can actually double the cpu speed, which is noticeable when graphing complex functions."

Comments

Not only is it faster

[Anonymous Coward]

But I get better results! Before, 1+1 was always 2, but now it's 2.0358!

Re:Not only is it faster

[Aero Leviathan]

Wow, just like a Pentium II!

Re:Not only is it faster

[Rangsk]

1+1=3 for extremeley high values of 1.

Re:Not only is it faster

[Michael Woodhams]

As always, Hewlett Packard got there first and better. (Yes, HP was once a great company, before the current management took over.) The very first hand-held scientific calculator, the HP35 in 1972, calculated exp(ln(2.02))=2. reference.

Re:Not only is it faster

[IgnoramusMaximus]

Ya think? Don't blame management.

You surely jest. The investors being increasing a pile of sheeple morons, intermixed with a few PHBs are demanding not profits (although in their deluded perception that is probably what they are thinking) but a buzzword-spewing, mindless technophobes with acting abilites to play a "part" of a "visionary" CEO, because that makes them feel that they "understand" tech companies. Look up the ./ article on buzzword bullshit just on the front page today, this is the same thing in different form. Hence Carly Fiorina, a total dumb-fuck whose claim to fame is revolving in the "right" circles of self-congratulatory aristocratic-born dimiwts. HP as a tech company is toast, but HP as yet-another mediocracy mass-consumerism crapola maker tied to fads and whims of "pop culture" and locked in endless "race to the bottom" against Chinese crap makers is just beginning.

Next:

[Pig Hogger]

Beowulf clusters of overclocked T.I. calculators!!!

From the

[ScrewMaster]

Too Much Time On Their Hands Department.

Re:From the

[RonnyJ]

Too Much Time On Their Hands Department.

Just wait til someone finally manages to overclock their watch :)

Sooo....

[Squatchman]

Slashdot, putting the "New" back in news.

Personally I think my calculator calculates rather well. If I was going to use it on a gaming platform(what's the point?) then I guess something like this would come in handy.

Re:Sooo....

[Anonymous Coward]

As well as yesterday's hack a day...

Re:Sooo....

[ottothecow]

Well none of it is really new considering there were plenty of instructions when I got my 83+ in 7th grade. They even prompted me to try to overclock a little 4function calculator...it kind of worked; the screen was sometimes a little garbled but the big square roots were slightly faster.

Not that I would do something like this to my beautiful TI-89...its amazingly difficult to find one in a store but I really dont like the feel of the titanium's shape or buttons (especially the arrow keys).

Boo TI for getting rid of the bombproof black case in exchange for changable faceplates!

pfft

[Anonymous Coward]

Pfft, tell me when you've over clocked a pencil and paper.

Re:pfft

[Anonymous Coward]

Pfft, tell me when you've over clocked a pencil and paper.

I've tried. The increased friction leads to heat problems and the paper catches fire.

Re:pfft

[SamSim]

What do you call a printer?

Re:pfft

[fcw]

I dunno, but I know how to call one: "Heeere, printy, printy, printy."

Dammit!

[Faust7]

I tried to overclock my slide rule, but it just went up in smoke.

Re:Dammit!

[goneutt]

My slide rule is a clock.... http://www.pulsarwatches.com/PulsarAssets/pdf/puls ar_rotary_slide_rule.pdfPulsar

Re:Dammit!

[FiReaNGeL]

According to the paper :

[Problem] 30 x 40 = ?
[Solution]
(1) Bring 30 on the bezel ruler and 10 on the dial ruler in line.
(2) Read the number on the bezel ruler scale corresponding to 40 on the dial ruler
scale. The number is 12 (= 1.2 x 101 ).
(3) Calculate the number of digits following the formula in " Hint for calculation of the
number of digits".
In this case:
30 = 3 x 101, 40 = 4 x 101, and 12 = 1.2 x 101
Z = 1+1+1(1.2 3, 4)
Z = 3
c = 1.2
C = 1.2 x 103 = 1200
[Answer] 1200

Sure speeds things up I guess :)

Not new at all

[Anonymous Coward]

This is soooo old. I overclocked my TI calc several years ago, putting a snazzy OC switch on the side. All of my friends were terribly impressed.

On the other hand, it didn't really help in my classes, except to get the wrong answer faster...

Re:Not new at all

[Drantin]

Actually, not only is the copyright on the website 1996-2000, but I've visited that site before... 4-5 years ago... for a website with more information, go here...

Cheating

[fembots]

Will students be caught cheating with these overclocked calculators?

It's not just TI calcs that can be OC'd.

[Slash Watch]

Utilities have been coded to overclock HP48/HP49 calculators to a wide range of clock speeds - you can pick and choose what you like, up to 200MHz. This is pretty impressive too - that's more than a doubling of clock speed, IIRC.

Re:It's not just TI calcs that can be OC'd.

[rritterson]

Actually, IIRC, the new calculators are using ARM processors running in some sort of emulation layer that tuned the CPU all the way down to 12MHZ so it would match the old calculators. The tool simply removes that restriction, if I understand right.

Re:It's not just TI calcs that can be OC'd.

[Nyall]

To save power the clock speed of the arm is lowered when it is idle, when calculations are running the 49g+ will raise the cpu speed to 75Mhz.

Re:It's not just TI calcs that can be OC'd.

[allanc]

Only works on the HP49g+, not the HP49g or the HP48 series.

Works really well, though. I enjoy the fact that I can overclock my calculator--which is already faster than the first Unix workstation I ever owned--so I can do my simple addition, multiplication, and subtraction problems at blazing fast speed!

another hack a day ripp off

[Anonymous Coward]

tsk tsk tsk how lame from the editors

Re:another hack a day ripp off

[EmbeddedJanitor]

Perhaps we need to overclock the editors??

hot off the press..

[fliptout]

Did this back in '96 on my Ti85.

Re:hot off the press..

[Solder Fumes]

Yeah, I know, this is pretty dang old news.

I even modded mine to have an LED and a port for standard 0.1" headers with access to power and the serial connection.

Re:hot off the press..

[Fjornir]

Heh. Not only is this 'news' more than 5 years old, this also ran on Fark today about 6 hours earlier.

Re:hot off the press..

[Oliver Defacszio]

I overclocked Earth the day before the dinosaurs died.

Seen this before

[Stevyn]

I've seen this for the TI-83 a while ago. I have the TI-89 now and it's great for the classes I take. I've overclocked cpus (AMD K6-2), but you've got to have some balls or some money to try and overclock a $150 calculator.

It just seems to me that the risk outweighs the benefits.

In the words of...

[MightyPez]

the Futurama cryogenic lab tech.... "Welcooome....To the WOOOOORLD of 5 YEARS AGO!"

battery drain

[Anonymous Coward]

This has been known for years. Keep in mind that overclocking by 2x drains the batteries by 2x as well.

Re:battery drain

[ivan37]

Indeed - years ago I overclocked my TI-86. After about 6 months I got really sick of buying new batteries and having the calc die when I needed it, so bought an 89 and sold the overclocked 86 to a friend for a pretty good price (although I think he regretted it later).

If you are going to overclock your calculator, make sure you've got some rechargable batteries and always have extras on hand.

Re:battery drain

[Jeff DeMaagd]

Keep in mind that overclocking by 2x drains the batteries by 2x as well.

It's not linear and there are a lot of factors. The switching current goes up by a factor of four for every frequency doubling. There's leakage current that stays constant regardless of clock, I think. And that's not saying anything about the rest of the circuits that might not be on the same clock, the CPU might not be a huge power drain in some circuits.

What about a wrist watch?

[Mario21]

I overclocked my casio wrist watch. Now I have all the time I need.

Re:What about a wrist watch?

[TheGratefulNet]

I overclocked my ethernet card.

problem is: where can you find hubs that support 12/120?

Re:The Point?

[Anonymous Coward]

which is noticeable when graphing complex functions

thats the point.

This isn't new...

[Cubeman]

I don't know what's wrong with the slashdot submission process, but this isn't a new site.

That site has been around for nine years, and in fact it doesn't list any of the popular TI graphing calculators today. The TI-83 Plus, 84 Plus, 92 Plus, and Voyage 200 are all missing. (Incidentally, this French guide will show you how to overclock your 83 Plus).

Sure it's a great site for overclocking older calculators, but please don't say "something new" when this has been widely known for years.

Re:This isn't new...

[ari_j]

I blame michael. Right now on the front page, there are 10 michael stories and 5 non-micheael stories. Most of the stories that have been pushed off the front page were michael stories, too, including one that was posted on Snopes as an urban legend long before it was submitted here. If he has that much time on his hands, he may not have enough time to actually fact-check anything, but it'd be really nice if he could put in the effort to time-check articles so make sure they're less than 4 years old before they are deemed front-page-worthy "news."

Re:This isn't new...

[jeremy_dot]

And the English version of that french guide is at
This site

Re:The Point?

[Spy Hunter]

Graphing complex functions is slow. Calculating integrals is slow. 3D graphs are abysmally slow. Speeding these functions up could be quite useful. Of course, you could just use Virtual TI on your PC if you wanted it to be really fast, or there's always Mathematica. I'm sure overclocking your calculator cuts the battery life in half or worse, which is why they are clocked so low by TI to begin with. Now if he could figure out a way for it to automatically overclock itself only while doing calculations (not waiting for input), then he might be onto something...

Re:The Point?

[enosys]

These calculators can do more complex operations like graphing and iterative numerical solving. These would benefit from overclocking.

They can also run interpreted and assembler programs. These would also run faster, but that's not necessarily a good thing because many are games that may become too fast and unplayable.

In fact...

[gotr00t]

This site was actually featured on ticalc.org extnsively a few years back. It's acutally nothing new.

RC oscillator

[morcheeba]

Wow, the TI-89 uses an RC oscillator for its clock! That kind of clock is one of the cheapest and least accurate, so I wouldn't want to run a real-time-clock off of it. I wonder if they have some sort of calibration mechanism on the production line, or if the processors are so underclocked already that they will surely work with a large variation of clock speeds. Even after leaving the production line, RC clocks drift and are more sensitive to temperature, so TI must always leave plenty of speed margin.

Re:RC oscillator

[Sycraft-fu]

That's precisely the case. The 89s use Motorola 68000s as their CPUs. You know, the same thing that the orignal Mac used. There has been just a few years of refinement that has gone in to it. Basically, they don't really care about precise clock speeds. It just needs to be in the ballpark of 10MHz, and only that since they decided it was an acceptable tradeoff of speed and power consumption.

I imagine that the chip is easily capable at running well over double it's nominal frequency, and infact probably other things would become a problem before it would. You have to remember, these are realyl simple devices. They don't need the precise timings that desktop computers have. For one thing they simply don't have a bunch of buses running at different, but related, speeds.

It's not a precision timing device or anything like that, it's a calculator. It's just made to give you easy, portable access to lots of common math functions. It doesn't need to have a precise clock. If my 89 executes a calculation in 5 minutes and yours in 4.9 minutes, we aren't really going to give a damn.

Graphing complex functions?

[return_of_ffalcon]

Wow! TI calculators can graph complex functions? Cool. I wonder how they portray four real dimensions.

Re:Graphing complex functions?

[oobob]

You graph complex numbers in the complex plane, silly =) One axis is the real axis and the other is the imaginary axis. Here's a brief intro from the math forum (a written intro, without graphics), and here's some more examples from a graphic intensive site that shows how you can perform operations on complex numbers like vectors. You can also do neat stuff like find the complex roots of numbers by manuiplating the graph, which is also mentioned in the 2nd site.

Yes, graphing complex functions quicker

[jj110888]

i'm sure the fact that theres more games then math programs in ticalc.org's asm sections will tell you what the extra cycles would be used for......

did in 80's with HP-41CV/X - anyone remember club?

[somewhere in AU]

Overclocking was done with switch which added capacitance when in parallel to get 2X.

Switch was flipped with magnetic rubbed down side of case and reed switch flipped accordingly.

Worked well on several modaseels (C/CV/CX) I had for internal calcs but not for card reader though which was rate dependent though!

Speaking of which also did internal 10 bit machine code using EPROMS - anyone remember the really neat "microcode" listings "published" within the PPC club based in US?

We had some members in Sydney and Melbourne etc who did the hardware mods as well as providing some neat software and by combining overclocking with machine code exec I managed translation of FORTRAN programme running on VAX with parallel processor and made into just 8K (2 x 4K ROMS) of machine code steps and could do some (very) heavy duty calculations when doing field geophysics in the early 80's - all battery powered and pocketable!

Alex.

Re:Pot?

[BobPaul]

you should have written it in assembly instead of TI-Basic.

Oh, and a POT is a varriable resistor. I think you might mean a trimmmer.

Actually quite useful.

[SharpFang]

Laugh all you want, these calculators are capable of stuff that's really time consuming.
Put

Y1=(somefunction)
Y2=FnInt(Y1(X),X,0,X)

Y2 displays integral of Y1. This isn't docummented anywhere and not without a reason. Getting the plot of even a simple function like Y1=sin(X) takes some 5 minutes as the integral is calculated separately for each pixel. Put more sophisticated function for Y1, or put Y3=FnInt(Y2... to get second integral and wait 2 hours or so for results easily.

In this case overclocking serves saving the batteries. True at double speed the batteries are used up nearly twice as much, but running for a hour at a single speed will drain them more than running for half a hour at double speed.

And yeah, these "insane" times are quite reasonable. I've been writing some cool stuff for my TI82. Generating a fractal took maybe a hour or so. "brute forcing" some logical problem lasted only 15 minutes just thanks to some luck (the solution was within first 5% tested). I found the graphs of integrals useful - I entered the function on the start of a test and could test whether my calculations were correct when it was drawn about the middle (and I had to use the calculator for other calculations). It was actually pretty fast at "your generic" numerical methods, and as we were free to choose the platform/language for writing our "numerical methods" programs, I didn't have to show up in the lab even once whole semester, wrote everything on the calculator.
One thing that sucks is lack of recursion support, Even the Prog[NAME]/Return function works only 1 level deep. But even this can be solved by using lists instead of local variables, matrices instead of lists.

Re:Actually quite useful.

[Geoffreyerffoeg]

This isn't docummented anywhere and not without a reason.

No, it isn't documented anywhere, except the calculator manual, pretty much every calculus textbook oriented towards the TI-8x, and even the MATH menu on the calculator....

Y3=FnInt(Y2...

You sound like you've never tried this (at least not on a recent calculator). On the 83 series, it gives ERR:ILLEGAL NEST, mainly because it'd take so long.

I've been writing some cool stuff for my TI82.

Ah. No wonder. The 83 runs slightly faster, the 83+ runs faster, the 83+ Silver runs considerably faster, and the 84+es run considerably faster than those. If you're writing fractals and brute force stuff, you'd do well to invest in the latest 84+ -- or even an 89-series. Do yourself a favor and sell the 82 on Ebay or give it to a teacher.

You say yours takes 5 minutes for fnInt(sin(X)). Mine, an 83+ Silver, takes about 20 seconds. Annoying, yes, but hindering, no. And it's safer than overclocking.

Incidentally, if you're running into the limits of TI-BASIC programming, you might be interested in learning assembler for the calculator. Just Google for "TI-82 ASM tutorial" or somesuch; there's plenty of tutorials of varying quality.

TI long in tooth?

[cgenman]

What happened to graphing calculator development? While I was in High School there was this burst of activity with the TI line, with frequent new models and upgrades. And then they stalled. And stymed. I got a TI-92 Plus my senior year in High School, and that has stayed TI's top-of-the-line ever since. It's like they've done zero development for the past ten years. You can get full color-screen Game Boy Advances with hardware far in advance of what you would find in a TI for about 100 dollars less, yet you have to use hardware trickery to fake greyscale on these dinosaurs. Their Ancient. Years after I've graduated college, they're still the best you can get. Now they're called the Voyage 200, but they're still the same 68000 - based calc with very similar limitations.

Where is somebody to steal TI's crown? Somebody has to recognize the power of full-color 3D graphics in mathematics. Doesn't anyone want the market TI has abandoned?

Re:TI long in tooth?

[jotux]

the voyage 200 is like half the size/weight, and has 2.7mb of flash memory. It's 12mhz, instead of 10 like the 92+...which isn't much of a difference but still. They've also just realeased the titanium editions, and you've kinda neglected all the HP calculators....which in reality are much more powerful than the TI's anyways.

When it comes down to it, who really wants a full color 3d calculator? It would basically have the performance of a PDA, and the same battery life. I can go about 10 months on new batteries with my v200, using it every other day. ...even the best PDA running simple apps could never compare to that.

Re:TI long in tooth?

[Shawndeisi]

Unfortunately, TI seems to have the market cornered with their non-feature-rich calculators. The more features you add, the less people will want them. This is inverse to what you would think, but it due to one large reason: "Education" Teachers wouldn't permit calcs that could be used as a game boy. Standardized testing wouldn't allow calcs with large memory and a notes program. It's all BS, but that's another comment.

Re:TI long in tooth?

[Teclis]

If you want 3D and color on a hand held graphing calculator, I think you are missing the point. The fact that we have these graphing calculators now is a real folly of our education system. People feel that they don't have to learn mathematics because their calculator does it for them. This is going to get you into serious trouble down the road. I've been through it. My first year university I bought me a shiney new TI-89 thinking that calculus will be a breeze for me.

It sure was! Just plug in my integral for x^2 and wow, symbolic calculations. Let's fast forward 6 years. The problems I encounter in physics are not the most complicated, but complicated enough. I've quickly learned that you can't trust the result of these calculators. In fact, 90% of the time, the calculator can't even do the computation. Simple problems on paper are impossible on my Ti-89.

My advice: buy a $5 add/sub/mult/div calculator and save yourself alot of headache. Learn the math inside and out and visualize the graph yourself on a piece of paper. Not only will you understand what's going on in the mathematics, but you will also save yourself a few bucks which is better spent on beer.

My Ti-89 now is used solely as a paperweight. Seriously, worst purchase I ever made.

Re:did in 80's with HP 41C

[hudsucker]

My HP 41C was overclocked in around 1984 or so, in the US. There was a company that sold the upgrade kit. It doesn't have a magnetic switch; it is controlled through a little tiny push button that is installed where the power plug opening is for the rechargeable battery pack option.

I think it is more than 2x, though. I thought it was 4x, but I could be wrong.

The overclock mode works great, except when you try to print through the IR port.

WOW! It really works!

[dimplemonkey]

Look what I got for the value of Pi after I overclocked my Ti! What a cool hack! 3.141592653589793238462643383279502884197169399375 105820974944 59230781640628620899862803482534211706798214808651 3282306647 09384460955058223172535940812848111745028410270193 8521105559 64462294895493038196442881097566593344612847564823 3786783165 27120190914564856692346034861045432664821339360726 0249141273 72458700660631558817488152092096282925409171536436 7892590360 01133053054882046652138414695194151160943305727036 5759591953 09218611738193261179310511854807446237996274956735 1885752724 89122793818301194912983367336244065664308602139494 6395224737 19070217986094370277053921717629317675238467481846 7669405132 00056812714526356082778577134275778960917363717872 1468440901 22495343014654958537105079227968925892354201995611 2129021960 86403441815981362977477130996051870721134999999837 2978049951 05973173281609631859502445945534690830264252230825 3344685035 26193118817101000313783875288658753320838142061717 7669147303 59825349042875546873115956286388235378759375195778 1857780532 17122680661300192787661119590921642019893809525720 1065485863 27886593615338182796823030195203530185296899577362 2599413891 24972177528347913151557485724245415069595082953311 6861727855 88907509838175463746493931925506040092770167113900 9848824012 85836160356370766010471018194295559619894676783744 9448255379 77472684710404753464620804668425906949129331367702 8989152104 75216205696602405803815019351125338243003558764024 7496473263 91419927260426992279678235478163600934172164121992 4586315030 28618297455570674983850549458858692699569092721079 7509302955 32116534498720275596023648066549911988183479775356 6369807426 54252786255181841757467289097777279380008164706001 6145249192 17321721477235014144197356854816136115735255213347 5741849468 43852332390739414333454776241686251898356948556209 9219222184 27255025425688767179049460165346680498862723279178 6085784383 82796797668145410095388378636095068006422512520511 7392984896 08412848862694560424196528502221066118630674427862 2039194945 04712371378696095636437191728746776465757396241389 0865832645 99581339047802759009946576407895126946839835259570 9825822620 52248940772671947826848260147699090264013639443745 5305068203 49625245174939965143142980919065925093722169646151 5709858387 41059788595977297549893016175392846813826868386894 2774155991 85592524595395943104997252468084598727364469584865 3836736222 62609912460805124388439045124413654976278079771569 1435997700 12961608944169486855584840635342207222582848864815 8456028506 01684273945226746767889525213852254995466672782398 6456596116 35488623057745649803559363456817432411251507606947 9451096596 09402522887971089314566913686722874894056010150330 8617928680 92087476091782493858900971490967598526136554978189 3129784821 68299894872265880485756401427047755513237964145152 3746234364 54285844479526586782105114135473573952311342716610 2135969536 23144295248493718711014576540359027993440374200731 0578539062 19838744780847848968332144571386875194350643021845 3191048481 00537061468067491927819119793995206141966342875444 0643745123 7181921799983910159195618146751426912397489

Already done

[Anonymous Coward]

Already done - your job's been outsourced to India, where they do your paper-and-pencil work faster for a quarter of the price.

Oh, we're cutting costs, so make sure to return your pink slip with your badge so we can use them both again.

Wow -- old news, New again (TM)

[Hex4def6]

This web page has not been updated since 2000... I remeber back in the day this was new and cool. 5 years though in internet time is like rediscovering the slide rule -- good job guys! I hear IBM are releasing the teletype II any day :)

its funny the progression that this story has taken -- it went from hackaday --> fark --> slashdot, and doubtless appeared on hackaday due to someone trying this trick out.

Yet ANOTHER hackaday plagarism

[FredThompson]

This is the SECOND repeat of a hackaday post in less than 24 hours.

That makes 3 or 4 in as many days.

How about something original, not plagiarized from another site WHICH WAS PROMOTED ON SLASHDOT A LITTLE WHILE AGO!!!!

Re:Yet ANOTHER hackaday plagarism

[Blakey Rat]

Slashdot is just reprinting Fark.com submissions. This calculator story shows up there this afternoon, and a few hours later it's here...

Nevermind that the Fark comments ALSO point out how this site 1) is a repeat on both sites, and 2) hasn't even been updated since 2000. Good job, submitter... good job, "editor."

Re:did in 80's with HP 41C

[somewhere in AU]

Actual overclocking rate varied in actual speedup vs reliability. (nothing new under the sun!)

2x was rock solid across several models and I recall other members getting 2.something before straying into areas of unreliability above that.

Of course we "only" had air cooled models so perhaps some mad scandinavian with -40c temps managed 4x but with the thick gloves necessary perhaps was never able to actually press the little black buttons to use at that speed! ;-)

Alex.

2+2=5

[Anonymous Coward]

For significantly overclocked calculators.

True story

[tepples]

Once I wrote a passable Tetris clone in TI BASIC to waste my spare time in class. Then I ported it to QBasic, and it started running at acceptable speeds even on an old-ass 8088. Then I turned it into C and made it run inside a graphical environment; this formed part of freepuzzlearena. Years later, I added a hallucinogen-simulating graphic distortion layer, first for the PC and then for the Game Boy Advance, resulting in TOD.

Re:Slashdot...

[NanoGator]

"ammm.... is this really a news item or just some sad person with way to much time." ... said the guy posting on Slashdot.

Re:Doom 3?

[tepples]

You can run Doom 3 on any graphing calculator: just load up a black screen.

http://hackaday.com

[killerface]

it seems that many articles are being taken from http://hackaday.com This and the altiods mp3 player were both featured there.

Paper and pencil might be faster

[MickLinux]

Seriously, if it takes 5 minutes to do an integral, then those calculators are ripe for reprogramming.

Seriously.

You could quite possibly do a numeric integral, faster, with paper and pencil.

http://csm.jmu.edu/physics/rudmin/ParkerSochacki.h tm

At this link, the author shows how to solve (exactly, numerically) a previously unsolvable system of differential equations using a relatively new (~12 yrs old) method.

Program your calculator to do that, and you'll be lightyears ahead of the competition.

Re:Dammit!-TurboGF.

[tuxter]

Girlfriend??? Please explain.

But can it run linux?

[Joshua53077]

or play .ogg files?

Sweet Zombie Jesus!

[laodamas]

Some information in this article is at least 12 years old. I remember overclocking my own TI-85, and then several friend's TI-85s in middle school. We then had fun writing benchmarking software that measured speed and how much error was introduced into mathmatical operations in both Basic and ASM (yay zshell!). No wonder I never had a date before HS graduation. I also installed the switch doodad under the battery cover so that I could switch to the original clock frequency when too much error was introduced around the 10e-6 and lower digits. Thank god I did not destroy any TI-85 PC boards with my $5 RadioShack Iron and my non-ESD protected work area. Anyway, the TI-85 uses a RC resonator to clock the CPU. When a smaller cap (1pf in this case) is substituted for the original, the RC constant becomes roughly 150% faster (cap takes less time to charge) which increases the overall speed of the voltage rise. This allowed me to build a 15MHz TI-85 that mostly worked. Incidentally the use of an RC resonator is why the calculator gets slower when the battery starts to sag-- apparently TI was too cheap to spring for a $0.20 quartz crystal.

Anyway, the TI-85 uses a RC resonator to clock the CPU. When a smaller cap (1pf in this case) is substituted for the original, the RC constant becomes roughly 150% faster (cap takes less time to charge) which increases the overall speed of the circuit. This allowed me to have a 15MHz TI-85 that mostly worked. Incidentally the use of an RC resonator is why the calculator gets slower when the battery starts to sag. Apparently TI was too cheap to use a $0.20 quartz crystal.

No kidding.

[raygundan]

This was going on when I was in high school, 10 years ago. (not that I'm incredibly old, but being ten years behind the curve is spectacular even for slashdot) You could overclock a TI-85 pretty easily, although it wasn't really necessary. The real joy was in installing a hacked ROM through an overflow on the link cable and running games written in Z80 assembly. It was the ultimate time-waster: a gameboy that your teachers allowed in class. TI even caught on later that their overflow bug had become a feature, and built in access to run assembly code on the TI-86.

There were some truly great games written, too. A few (Sqrxz comes to mind) even eventually made the leap to the gameboy.

Re:No kidding.

[afidel]

Actually there were times when an overclocked Ti-89 would have been quite usefull to me, mostly when doing 3D plots. Plotting a series of partial differentials and rotating them in 3D was quite slow on the 89, on the order of a few seconds per frame. I eventually ran the Ti-89 firmware in an emulator on my laptop which gave ~5x normal performance and the graphing was quite nice at those speeds. Of course then I lost the great input interface, no laptop will ever compare with a dedicated graphing calculator for ease of input for mathematical equations.

Re:No kidding.

[punkrockguy318]

Yeah, i'm a highschool student now.. There's an application out now (MirageOS) that can run ASM games and advanced BASIC games. That's the only way I got through Health class, heh. The big games they play now include a mario3 clone, megaman clone, pheonix 3 (space invader like game), pacman, zelda clone, and lots more. It's getting serious. Unfortunately, some of the teachers are catching on. But I'm sneaky :-P

Re:No kidding.

[kasperd]

This was going on when I was in high school, 10 years ago.
I also heard about this stuff when I was in high school 10 years ago. Some of my friends had TI-85 calculators, but I don't think any of them actually ever overclocked it.

The real joy was in installing a hacked ROM through an overflow on the link cable and running games written in Z80 assembly.
I tried some of those. But it wasn't really about hacking the ROM. The ROM was never changed, and if you removed the batteries it would still be restored to its original state. Also the way the assembler programs were transfered to the calculator was not through an overflow, but rather through a backup feature the calculator had. These calculators had a link cable, and one of the usages for this link cable was to create a full backup of the RAM. This full backup could either be stored on a PC using a special link cable or transfered to another calculator using the standard link cable. Transfering such a backup to a calculator would overwrite anything already in the RAM.

Now the trick was to create a backup on your PC and manipulate it there before transfering it back to the calculator. Inserting ASM code was the easy part, AFAIR it would all be put inside string variables which the standard software allowed you to manipulate. Actually executing this ASM code was the neat trick. This calulator had too many functions to make all directly available, for that reason it had a custom menu where you could put five of those for quick access. Now this was implemented using a pointer to the actual code in ROM for the selected function. In the manipulated backup one of this pointers would be altered to point into RAM rather than into ROM.

Once the backup image was ready it could be transfered to a calculator. The only way to insall this software on the calculator was through a full restore. But that could even be transfered from one calculator to another. Once you had the basic menusystem to access the ASM programs, you could transfer individual programs between calculators using standard features in the ROM. One drawback of using those ASM programs was, that while they were running the calculator wouldn't automatically turn off after some minutes of idle time, so you could easilly run down the batteries and would then need to start from scratch.

But....

[AVryhof]

But I really wanyed to overclock my TI/99....just wondering how fast the Wumpus could run.