There's a great presentation from the recent HHC conference, about building a series of DIY calculators based firstly on microcontrollers (430, ARM) and then on 6502.

HHC 2019: DIY Calculators (YouTube)

One of the challenges is the construction of a good keyboard with stable labelling, which is mentioned in the presentation and also on the nearby blog. (As is the question of writing fast code for the arithmetic)
http://joldosh.blogspot.com/search/labe ... ulator?m=1

See also these nearby threads:

Button caps
Fast BCD multiplication
Javascript 6502 emulator
Assembly optimizer

(This presentation and project is Druzyek's I think, going by a different name.)

Thanks for sharing. I had not realized the new HHC videos were up yet. They are always sooo interesting

Thanks for the video. He did seem a little critical of the 6502. Or maybe I just misunderstood.

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Cat; the other white meat.

Seemed fair to me: he notes that stack-based addressing isn't efficient on 6502, and that it's worth managing zero page usage well instead (using a common block, in effect, like Fortran, rather than using stacked variables like C).

What I got was that he said that the 6502 really only had two "usable" registers because one is used for addressing. And, the usage of ZP memory was wasted if you weren't using them at the moment.

I mean, that's probably true to some extent. But what's he comparing it to? Modern ARM processors? Is the Z80 any better?

I guess any negatives about the 6502 is like calling my child ugly. LMAO.

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Cat; the other white meat.

I'm surprised to see you challenging someone who's written a 6502 emulator and is working on a zero-page storage allocator, and building a scientific calculator based on 6502, as being in some way negative on 6502.

As the 6502 isn't perfect one can usefully say things about ways in which it's awkward.

It's worth perusing his blog: he's considered some dozen or more microcontrollers, out of interest presumably, and is proceeding with the 6502 at present out of nostalgic fascination. I can understand that!

I didn't think I was challenging or being really negative. Sorry if it came off that way.

Being a fan of calculators myself (including working on designing one around the 6502), I certainly am a fan of what he's doing. I guess I just was a little taken back with some of the stuff he said about the 6502.

I've never read his blog but maybe I should.

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Cat; the other white meat.

Hey guys! Thanks for watching my video.

cbmeeks, thanks for your comments. You didn't seem negative to me, and I think your questions are fair. I should say I didn't know I was presenting until the day before and threw together some stuff I had the night before, including what I planned to say. Maybe I didn't explain my point about the 6502 as well as I would have liked to. My criticism is not that there is anything wrong with the 6502 so much as using the X register to keep a stack in zero page is slower than statically allocating addresses where possible like I'm trying to do. Even more important (to me at least) is that all else being equal, you can write faster code with A,X, and Y free than just A and Y. So the "only two usable registers" comment was related to the case where you chose to let X be your zero page stack register. The comment about ZP being wasted was about the other scenario where you assign each function a chunk of zero page and never reuse it even if the function isn't running. Sorry if it wasn't clear! I'm still a big 6502 fan

Hey, no worries! My own idea of a 6502 calculator were much simpler (not scientific). I did some RPN stuff in .NET years ago and sort of developed a passion for it. Even though I still get tripped up by it sometimes.

But I wanted to create a calculator that looked like it came from 1972. Big bright digits and basic functions.

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Cat; the other white meat.

That sounds cool! I thought about doing a different project with a big display that would look good sitting on my desk at work even if it wasn't that portable. It will be cool to see what you come up with!

I seemed to have recalled seeing a calculator project here a while ago. A search came up with this:

viewtopic.php?f=2&t=3639&hilit=calculator+project&start=0

Nice project Calculi!

Cheers,
Andy

Hello,

I've been away for a long time, but I regularly peek at the forum... and surprise, a reference to my already old project. Thank you, Andy and here's a little update :

My calculator still goes strong, I use it regularly. Last hardware / software updates have been done 2 years ago : I ramped the clock up to 8 MHz (still stable at 10) and did many little optimizations. I also made some PC utilities to edit programs and download them into the machine. The user code now runs at an average speed of 3,400 steps / second, which I find very satisfying.

My new job takes me too much time for a new serious project, the only 6502-related fun I recently had was fixing a Rockwell AIM-65 board found at a flea market for 10 euros... No keyboard, no printer, but I was quite happy anyway. A few components were missing in the clock section and some hacks had been done to fit the board in an industrial machine. I reverted it back to its original state and everything works fine

Cheers,
Marc

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