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.

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.

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.