
Show HN: KnightOS – An open-source OS for calculators - ddevault
http://knightos.org
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sleepychu
I'd never really considered this till now but all those "you must wipe the
calculator's memory before the exam" rules are totally owned by installing a
sufficiently deceptive custom OS.

Like another commenter, I wrote some of my first programs on a TI-84, amazing
that the school encouraged us to buy them and then completely failed to teach
anyone how to use any of the features :'D

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vanderZwan
> that the school encouraged us to buy them and then completely failed to
> teach anyone how to use any of the features :'D

This is exactly the kind of thing Seymour Papert warned against; just like
handing out tablets and then _stopping the students from learning how to
unlock them for their own uses_ defeats the whole point.

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fimdomeio
I would say that for future hackers putting a calculator/tablet/whatever in
one's hands and then trying to limit it's use just adds to the fun.

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vanderZwan
That's good for finding the natural crypto people who like to break out of
such crippleware restrictions, but I can't think of anywhere else in the
industry where that is useful selection bias.

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eitland
Senior sysadmins? SW developers above CRUD level?

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webkike
I dunno, the HP-50g was the pinnacle of calculator OSs for me. RPN, stack
based programming, lisp. It really was wonderful.

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unixhero
Why is RPN good?

My gripe is:

\- Why should a person doing difficult mathematics also have to struggle with
a different notation?

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kmill
Basically, when you're using a calculator, you're calculating, not notating.
With RPN, you have a data stack, and everything you do is an action you
perform on this stack (like entering a number or doing an operator). You can
see your calculation in progress. It can be somewhat natural to put verbs at
the end ("3 and 4's sum" for instance), and you don't have to think ahead to
figure out whether you'll need parentheses.

If the expression gets to complicated, though, traditional notation is nice
because it's easier to verify you calculated what you intended to, I feel.

But let me deconstruct your gripe. A good part of mathematics has been about
finding the right notation to express particular ideas. RPN, in my experience,
makes it easier to express certain calculations to a machine. But: why is
there 'should' and 'have to' in your gripe? No one is forcing anyone to use
RPN. You struggle with it to learn the notation, and maybe it makes the
"difficult mathematics" easier to deal with. It's not like people make RPN
calculators to be intentionally difficult and alien.

Your gripe could equally apply to modern algebraic notation vs. the old latin
longhand, or arabic numerals vs. roman. I'm sure it was a struggle for people
to learn the new notation in either case.

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thesmallestcat
Wow OP, this is a ton of amazing work (in the GitHub organization). Your blog
is great too. Do you have any advice for being so prolific? My butt can't take
the sitting and my shoulders can't take the typing posture for the amount of
time it seems to take to churn out so much (not being sarcastic in the least).

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Sir_Cmpwn
Thanks! I just spend a lot of time working. Maybe you can look into more novel
keyboard designs and nicer or novel chairs? I use a mechanical keyboard with
cherry MX blue switches and an above-average desk chair.

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thesmallestcat
The above-average desk chair has made a huge difference but I've been using a
cheapo keyboard for ages now, will have to get on that. Do you use a keyboard
tray?

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Sir_Cmpwn
No.

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qwertyuiop924
I hear Drew's done some great work with this. I'd look at it myself, but
flashing my calculator firmware is a bit risky for such an overpriced device.

Thank you, College Board.

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Sir_Cmpwn
FWIW it's very difficult to brick a calculator without doing so intentionally.
The boot sector has a recovery mode built in for reflashing in case of the
worst and the boot sector itself is write protected except in some very
exceptional circumstances.

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qwertyuiop924
Ah, good. Thanks Drew. By the way, I didn't see any actually, you know,
_graphing_ applications in the repos. Those exist, right?

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MaxLeiter
They don't - KOS currently doesn't have FP support (although the C library[1]
does provide FP, it's not too accurate or fast)

[1]
[https://www.github.com/KnightOS/libc](https://www.github.com/KnightOS/libc)

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qwertyuiop924
FP?? I was asking about using the calculator as a calculator.

EDIT: Oh, floating point! Now it makes sense!

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boyce
Anyone looking to have a play without finding their TI link cable - works on
Andiegraph TI emulator from F Droid

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tombert
This deserves all the upvotes. You saved me a trip to eBay.

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linohh
When I was in school (10+ years ago) we already had elaborate mods for the
TI83+ used for cheating our way through the final exams. Also we overclocked
the hell out of them. Those were the days.

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overcast
I've still got my trusty TI-85 sitting next to me at the desk here, from
twenty years ago!

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niftich
Ah, TI-83! I wrote my first-ever programs on this thing.

The 'getting started with assembly' guide is really good; the whole thing is
really inviting to tinker. Excellent work!

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unixhero
No install guide in the wiki. Humm.

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Sir_Cmpwn
[http://knightos.org/download](http://knightos.org/download)

