DB48X: HP48-like RPL implementation for DM42

[rprosperi]

(10-30-2024 12:55 PM)floppy Wrote:  Exact. For me,
- the DMx path is way too expensive
- the other direction (most impressive for me this year) is the RPN83 way: with very very cheap HP83 or HP84 hardware, you can have an RPN calculator.
So, please, we need now the calculator for the poor, and not only calculators for the rich.

I assume you mean TI83 and TI84 ??

[LinusSch]

(10-30-2024 12:55 PM)floppy Wrote:  So, please, we need now the calculator for the poor, and not only calculators for the rich.

Noted and seconded.

I have a spare 50g so that makes sense to me, but those are getting harder and harder to come by. I could get my hands on some cheap TI hardware and theoretically I could have a go at making it work. But there are many things I want to spend my time on and few things I actually end up spending time on. No promises.

[Gjermund Skailand]

Hi
I am running DB50X v. 0.8.3 on DM42N
I just started playing with this wonderful software, and may have done a lot of strange things.
There seems to be something wrong with matrix Random and HwFP Prec 7. Can someone confirm if they also get hard fault crash with the following setting?
shift MODES HwFP
shift DISP 7 Prec
{ 3 3 } shift shift MATRIX Random

The battery is running low, but the same happens on USB power.
best regards
Gjermund

[Gjermund Skailand]

Hi
there is also something else strange happening on DM42N when calculating directly from commandline using CATALOG menus
e.g
6 ENTER SHIFT CATALOG !
is ok

whereas
6 SHIFT CATALOG !
result in rubbish or it hangs
Maybe due some pointer error?
PS it does not happen in the browser.
best regards
Gjermund

[LinusSch]

(10-30-2024 10:01 PM)LinusSch Wrote:  

(10-30-2024 12:55 PM)floppy Wrote:  So, please, we need now the calculator for the poor, and not only calculators for the rich.

Noted and seconded.

I have a spare 50g so that makes sense to me, but those are getting harder and harder to come by. I could get my hands on some cheap TI hardware and theoretically I could have a go at making it work. But there are many things I want to spend my time on and few things I actually end up spending time on. No promises.

I looked around a bit and I found the following thoughts:

• TI 83 plus and 84 plus can work
  • but 512 kiB flash in the 83 plus may be limiting
  • Silver edition hardware has enough flash to maybe put db48x in there as a program
  • the display resolution of 96x64 may be tough challenge
  • the good ones are more expensive than I had guessed, on my used market
    
• TI 89 seems better
  • a display resolution of 160x100 is a definitive step up
    
• agarza's PX41CX has too limited flash
  • finding a 28-pin microcontroller with at least 1 MiB of flash may or may not be possible, at least it is not easy
  • the 250x122 pixel display is a welcome step up from TI hardware
  • this isn't really cheap
    
• Raspberry Pi Pico and Pico 2 may be a good way to get a good chip
  • 2 MiB flash on the original, 4 MiB flash on the Pico 2, compute power overkill but I like overkill
  • these are really cheap for what we get
  • displays are the challenge:
    • Adafruit sells a module with the 2.7" 400x240 Sharp Memory LCD that is pretty much perfect for calculators, yes, but it is... not exactly cheap (and requires soldering I think) https://www.adafruit.com/product/4694
    • Pimoroni had a 2.8" 320x240 IPS display at a better price, still a good chunk of the entire build cost, can be plugged in without soldering if your Pico has headers, eats more power and it is currently out of stock https://shop.pimoroni.com/products/pico-...y-pack-2-8
      
  • well there we go, everything except keyboard and case, 2.4" is a slight step down in size, eats power but not wallets https://shop.pimoroni.com/products/tufty-2040
    

The prices I found were

• 800 SEK for a good used TI
• 50 SEK for a Pico or 80 SEK for a Pico 2 so those are cheap as chips
• 700 SEK (but only $45) for the Adafruit display module
• €19 for the Pimoroni 2.8" display
• €24 for the Pimoroni Tufty 2040 that really seems tempting
  

That's more than enough calculator musings for my Saturday, I need to get my misbehaving computers in order.

[jibanes]

Another approach would be a hp48 (there are thousands on ebay, many under $100); gutted out with its internals replaced with a swissmicros-compatible (or like) internals (including LCD); basically you'd be buying the hp48 (or really hp50) just for the keyboard and shell. The PCB would be powered using the AAA batteries.

But then again, if db48x/newrpl comes to the hp50, then there's no need for the surgery. I just dislike keyboard overlays and stickers.

Meanwhile I use db50x on my dm42n daily.

[spiff72]

(11-02-2024 05:20 PM)jibanes Wrote:  Another approach would be a hp48 (there are thousands on ebay, many under $100); gutted out with its internals replaced with a swissmicros-compatible (or like) internals (including LCD); basically you'd be buying the hp48 (or really hp50) just for the keyboard and shell. The PCB would be powered using the AAA batteries.

But then again, if db48x/newrpl comes to the hp50, then there's no need for the surgery. I just dislike keyboard overlays and stickers.

Meanwhile I use db50x on my dm42n daily.

NewRPL is already available for the 50g - am I missing something in this discussion?

[nickapos]

(11-02-2024 06:46 PM)spiff72 Wrote:  

(11-02-2024 05:20 PM)jibanes Wrote:  Another approach would be a hp48 (there are thousands on ebay, many under $100); gutted out with its internals replaced with a swissmicros-compatible (or like) internals (including LCD); basically you'd be buying the hp48 (or really hp50) just for the keyboard and shell. The PCB would be powered using the AAA batteries.

But then again, if db48x/newrpl comes to the hp50, then there's no need for the surgery. I just dislike keyboard overlays and stickers.

Meanwhile I use db50x on my dm42n daily.

NewRPL is already available for the 50g - am I missing something in this discussion?

Newrpl is not as feature rich as DB48X. Also is is not under active development any more.

[jibanes]

> Newrpl is not as feature rich as DB48X. Also is is not under active development any more.

Oh thanks, I didn't know newrpl was stable. I will definitely give it a shot.

[n3mmr]

(11-03-2024 02:56 AM)jibanes Wrote:  > Newrpl is not as feature rich as DB48X. Also is is not under active development any more.

Oh thanks, I didn't know newrpl was stable. I will definitely give it a shot.

It isn't really stable, the author just stopped working on it.

And the db50x is potentially a really complete implementation, if Mr de Dinechin can find the time to take the project all the way.

[LinusSch]

I keep forgetting that I actually need to learn building Android apps. Which creates an obvious answer to what zero-budget db48x project I should actually attempt. Both the process and the result would be of most use to me personally if I did that.

So why... maybe I just want to look at hardware options for hours, without looking in my drawer of old phones for some reason.

Physical keyboard, you say? Most Androids happily accepts standard USB keyboards and I think that can be made use of to have the app double as a true desktop calculator. Phone screen can then be only screen, no keys... not the best aspect ratio, but with single line soft menus and landscape orientation I think three levels of the stack could be shown in a reasonably large font. Not high priority, not at all, but this possibility makes me at least a little excited - so that maybe I'll eventually get to work.

[raprism]

(07-11-2023 10:16 AM)c3d Wrote:  

(07-10-2023 09:46 PM)Helix Wrote:  I would be curious to know the result for this benchmark too.

I used the following program:

Code:


« Ticks 0 1 10000
for i
    i atan sin exp cbrt +
next Ticks Rot - »

The result for 10'000 loops is
- USB: 12.5s (stock DM42 is 26s)
- Battery: 36.4s (stock DM42 is 65.73s)
[/code]

Because of the current release doc in dev branch ("0.8.4") I researched to find the code of this benchmark "floating point sum" test. With 0.8.4 self-compiled from dev branch, and the released 0.8.3 I used this code:

Code:


« Ticks 0 1 1000
for i
    i atan sin exp cbrt +
next Ticks Rot - 1000 ÷ » 'T1K' STO

Note that T1K uses 1000 instead of 10000 loops, because timings were far slower as expected - although I can confirm the speed-up from 0.8.3 to 0.84. Results for DM42 USB-powered are:

• 0.8.3 ~18.3 s
• 0.8.4 ~16.2 s
  

What might be the reason that some early db48x version was much faster when running this test?

[Dashier]

There's a Facebook thread regarding a test of calculator accuracy based on an exam question that results in:

Code:

 (SQRT(2)-1)^10 = 3363-2378*SQRT(2)

There are a number of comments regarding the accuracy of various calculators.

I elected to set the DB50X to 2000 digits precision and test it. The difference between the LHS and RHS was 2.15651x10^-1997

Nice job Christophe!

[LinusSch]

(Yesterday 08:37 PM)raprism Wrote:  What might be the reason that some early db48x version was much faster when running this test?

Early versions used the Intel decimal floating point library, current versions use a custom floating point library that saves a lot of code space as compared to the Intel one and provides arbitrary precision. If you set your precision low enough the current versions should be able to go faster than the early versions, but I do not know how low you'd need to set it for which cases.