## Color-Screen TI-84 Plus Calculator Leaked 245

KermMartian writes

*"It has been nearly two decades since Texas Instruments released the TI-82 graphing calculator, and as the TI-83, TI-83+, and TI-84+ were created in the intervening years, these 6MHz machines have only become more absurdly retro, complete with 96x64-pixel monochome LCDs and a $120 price tag. However, a student member of a popular graphing calculator hacking site has leaked pictures and details about a new color-screen TI-84+ calculator, verified to be coming soon from Texas Instruments. With the lukewarm reception to TI's Nspire line, it seems to be an attempt to compete with Casio's popular color-screen Prizm calculator. Imagine the graphs (and games!) on this new 320x240 canvas."*
## And for all of us who prefer RPN? (Score:4, Interesting)

Have HP done something lately?

## Certified dumb for school use? (Score:5, Interesting)

Will this be a "certified dumb enough for school use during tests" device?

## Re:And for all of us who prefer RPN? (Score:4, Interesting)

Indeed. I'm clinging on my HP-48s, and I dread the day they'll stop working, because absurdly old tech or not, there's just nothing better on the market right now.

## My Casio fx 82 still works (Score:4, Interesting)

after 30 years! Used, overused and abused. Thrown in the wall, broken, reassembled. Loved.

Unfortunately my even older Texas Instruments was stolen some thirty years ago.

Before those, at school we used http://en.wikipedia.org/wiki/TI-59_/_TI-58 [wikipedia.org]

And before that I got my Citizen. Don't recall what model though.

Those were the days.

BTW, is there no web page with images of all these old models? For nostalgia.

## Re:Superseded (Score:5, Interesting)

## Re:Certified dumb for school use? (Score:4, Interesting)

The entire math curriculum was design around the limitation of that calculator. Also it helped that most problems that the calculator was unable to solve by itself had a methodical solution taught in the textbook.

So for the problems where the calculator was able to compute the correct answer, I would compute and pretty print the intermediary step backward from there. For the few problems that were beyond the calculator reach I would compute a lot of discriminants, keep the one that matched a known solutions family then I would extract the meaningful coefficient and pretty print the solution with the test used.Since that software was written on the ti-92 keyboard procrastinating instead of drilling myself with math problems in the directed exercise portion of the math classes.

## Re:HP-15c fiasco: HP doesn't want your money (Score:4, Interesting)

I hate chinese knock-offs, but when a shady-market HP-15c clone comes out I'll order a whole shipping container of them.

There is a 15C knock-off, but Swiss,not Chinese:

http://www.rpn-calc.ch/ [rpn-calc.ch]

The downside is that it's much smaller and without the HP feel of the keys. The plus side is that it uses the original ROMs, so it's more HP-15C compatible than the HP-15C-LE is.

## For what it's worth... (Score:4, Interesting)

...I took my Comp Sci students on a tour of TI's DMOS6 fab in Richardson, TX last year. (Rather fascinating, BTW, largest completely automated fab in the world at the time, since replaced by a

biggerTI fab!). At any rate, our tour guide (an engineering type) told us TI got out of the calculator business years ago. The only thing a TI calculator shares with TI the company is the name stamped on the case and a couple TI chips inside. They are designed and built by non-TI companies.## Re:And for all of us who prefer RPN? (Score:5, Interesting)

So I ask: Why do you, Slashdot users, like RPN?

I don't know that I can really articulate it, either, but I can report the results of an interesting experiment I participated in about 20 years ago.

I was an RPN-lover even then, having recently graduated from my 15C to a 28S, but most of the other geeks in the university computer lab where I spent a ridiculous amount of time couldn't see the sense in it. Late one night the discussion got somewhat heated and someone said that an advantage of RPN was that it was faster because it required fewer keystrokes. A measurable claim like that immediately sparked a demand for proof, so we decided to do some comparisons.

One guy got on the whiteboard and wrote down four very complex arithmetic expressions. Then for each expression, two candidates were selected, one from the RPN camp and one from the infix camp. Each was to write down on the board, under the expression, the series of keystrokes that would be needed to evaluate it. In all cases the RPN keystroke list was shorter, often considerably, but after the first was done everyone noticed a second interesting and unexpected outcome: The RPN-wielder finished writing down his keystroke list long before the infix-wielder -- and not just because of the number of keystrokes. Everyone watching noticed that the infix-proponent often paused for a second or two to think about how to handle the next bit, or stopped for a moment to go back to count up parentheses. In contrast, the RPN-er never paused, never hesitated, just wrote down keystrokes as fast as he could.

After that, we all decided that we should also time the remaining trials, which were all conducted with different candidates. The RPN user consistently finished 25% faster than the infix user, even though the keystroke list was only about 5% shorter.

Then someone (I think it was actually someone from the RPN camp) decided to write a truly horrendously complex expression. It had fractions nested at least ten layers deep and was, frankly, ridiculous. Two more stepped up to try and, once again, the RPN user wrote down keystrokes in a long list, without any more hesitation than it took to find his place in the expression. The infix guy, on the other hand got badly bogged down, backed up several times and ultimately gave up after his RPN competitor had been watching him struggle for five minutes.

To top it all off, actually punching all those keystrokes into real calculators showed that RPN was more accurate. On only one of the five problems was the RPN calculation not correct, while the infix calculation was incorrect on three out of five (determining which answers were correct took significant time and much arguing).

Bottom line, per our impromptu tests and my personal experience, RPN is faster and easier.

I could easily explain why it requires fewer keystrokes, but why exactly it requires less cognitive effort is harder to describe. I believe, though, that it's because when you use RPN you pick a "path" through the expression, and then just follow it. At each point along the path you only have to remember where you've been and where you're going. The calculator keeps track of the stack. With infix you have to manage the "stack" in your head, figuring out when to add and remove nesting levels with parentheses. That's not exactly right, but it's as close as I've been able to come.