My friend had a Sentry CA756, but the EXE button stopped working, and he gave it to me (but I can't fix it). These graphing calcs are about $20, with a very small screen and only 10 program spaces. Yes, 10. You reference them by using Prog, like Prog 1. It's looping capabilities are lbl, goto, ISZ, and DSZ. Sad, isn't it? And it doesn't even have a function catalog! You have to access function with a Shift- or Shift-Alpha- key sequence. To change the calc's mode, you have to press MODE, MODE-SHIFT, or MODE-ALPHA and a number.  D: This thing is awful! So, without further ado, here are some pix!

Here's the awful small screen and the label that tells all the calc modes.



Sorry about this one being blurry, but here's the keyboard. As you can see, almost all of the keys have SHIFT, ALPHA, and SHIFT-ALPHA labels on them.



Here's a close-up of the arrow keys. Notice how they stole the "REPLAY" and "EXE" from Casio.



The "screenshots" on the quick reference aren't even screenshots. They didn't even attempt to make them look real.



The battery. Notice how the calc only needs one battery to work, so they just glued foam to the other contact!



This is the inside of the calc.



The main (and only) chip is, of course, buried under epoxy.



Here you can see that foamed-up battery slot also has terminals running to the circuit board, just like the other one!



The only thing holding the LCD in is the back cover pressing against it. I can freely pull it out of its slot (that is too big, the LCD can wobble all around in the slot).



Another shot of the calc, this time with the LCD flopping.


You have just witnessed how awful this cheap, $20 calc actually is. It's definitely worth less than $20

Actually, I'm moderately impressed that a $20 calculator is programmable at all. I'm a bit curious what sort of processor/memory they have under that epoxy blob, whether it's something standard or custom.

I meant to post my opinion yesterday, but this is basically my verdict. I think it's definitely worth $20 considering how much an 84+ costs in comparison

Definitely. To expand on my wondering about what sort of hardware is lurking under that epoxy, I'm curious how much this could be hacked and expanded. If a TI calculator is already a fun challenge for hacking, this seems like it would be an even bigger and potentially therefore more rewarding challenge.

Back in the 90s, I saw a $20 programmable calc (Sharp, I think) in a catalog, but it was just scientific, not graphing. I wanted it but I later eventually settled on the TI graphing calculators I started out with, which probably eliminated my interest in the lower-level models.

I wonder if this calc is actually a rebranded Casio, given the similarity in the keys and the mode-number key sequences that many Casio scientifics used.

Oh good, it's not just me. I thought that looked awefully familiar from my experiences with the Casio scientific calculators.

I hope that smiley means you're kidding. Why would you pay that much for this? But I suppose if TI calculators are the scale, then I'll go along with that statement.

Smiley means happy, non-sarcastic verdict, so no, I hold to the $20 verdict This thing is a lot cheaper than alternatives, and still has many capabilities not found in similarly priced TI/Casio Scientific Calculators. $20 seems about right for a very low end 84+ replacement.

$20 seems pretty cheap for something that can be used for arbitrary programming to me, personally.

So one man's trash is another man's treasure? Fair enough.

Well, it depends on your perspective. Most computer coders would find (and do find) calculator programming laughable, but we here in the community know how to appreciate the challenge that it provides. Similarly, I see this as even more of a challenge as far as a lower-cost, lower-capability device that still somehow has cool programmability.

I'd rather get a $30 86 from amazon, or a raspberry pi but I suppose if I already had one I'd mess with it. I've heard there are ways to get epoxy blobs off of those things with the right chemicals and whatnot.

http://www.amazon.com/gp/offer-listing/B00000JF53/ref=dp_olp_used?ie=UTF8&qid=1325405691&sr=1-1&condition=used

I rest my case. That's a lot more powerful.

And it seems there's a steady supply. I got my 86 for $30 4 years ago, and I've never seen a change in the lower prices. None of them are in non-working condition either.

Also, the thing I find most fascinating about calc programming over computer programming is how much is known about the hardware. We know these calculators so well that we make programs that far exceed the expectations people put on things 5 times faster. That's impressive. Imagine a PC world like that. Skyrim could run on a PIII. But it really requires the hardware specialization we only see in areas like this, where asm is really the most viable language, not C. C has a tendency to hide what slows it down the most on a low level.

Interesting, I didn't realzie that Amazon had those kinds of deals. I'm used to getting very inexpensive TI-83+s that require some repair. I wonder what they have in the way of Prizms.

This is also the reason why console games can run quite fast even with the often meager specs of the system. The people who write the libraries and compiler for the console have a single target. Thus, there are far fewer layers of abstraction and the code created can be very close to the hardware.

While it is true that hand optimized assembly will almost always be faster than equivalent C code, it's often the libraries that slow things down, and there are quite a few cases in Windows where a function calls a function that calls another function, memory is read to see what other functions it should branch to for compatibility, etc. On an integrated system, a lot of it is cut out because there will only be one specific set of hardware running this code, so all of those checks are wholly unnecessary.

Anyways, on topic: That calculator doesn't look at all shabby for $20. I wonder why schools don't get these on the cheap instead of expensive TI-84's or even worse... TI-nspires!

My school doesn't get ripped off at all. They rent calcs out for $30 a trimester, so their investments are paid off in under 2 years. And those calcs are a lot more than 2 years old, most of them are 82s. It's nice to see the school being smart about products. They seem to be on a smartboard kick, though.

I realized that this is a very outdated, but I disagree. I am primarily a Java/C# programmer for computers, yet I find calculator programming very enjoyable (I.E. It's mindless, but not TOO mindless).

Please try to avoid necroposting in the future, unless there's a very good, on-topic reason (and your post was only half-related to the topic's original subject). I will address your point, though: I think the vast majority of us do enjoy the challenge of trying to program on a limited platform, or we'd just program for computers instead.