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

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.

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.

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...

[jeremy_dot]

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

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.

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.

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: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.

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...

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.