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Just ordered a DM42
05-06-2019, 03:44 PM
Post: #1
Just ordered a DM42
Hi all, I'm new here.

Long story short, I've decided to teach myself math. Had a pretty terrible math education (all of my worst teachers in high school and college were math teachers) and I find it annoying that I just don't 'get it'. So I decided to jump back in and learn it as a hobby. Well I needed a calculator right? So I got a TI 92+, which turned into a couple of Casios, a Prizm, and then an HP 50g and a Prime over the course of a couple of years. Hey, a hobby has to have gadgets, right? That's mostly thanks to random post results through google from here too.

While I enjoy all of them, one thing stuck out: the 50g. Having absolutely no experience with RPN/RPL, I was forced to learn it to use the damn thing... and I quickly found that RPN is the most helpful of the bunch when learning math, or at least, it is for me. Once I got it, I found it to be more of an ... extension of my brain I guess? Not only is it faster, it breaks down problems into component bits, forces me to 'walk' through them rather than just key them in, press a button, and see the answer. In the process, this often teaches me *where* I'm going wrong learning something. Super useful.

In the end, I ended up reading a bunch of stuff here about RPN, which led me to the HP 42s, and then, the new DM42. Given how much I'm learning with these things, I figure $200 on a new cal with pc-transfer capabilities was worth the expense... and now I'm waiting like an impatient child for the damn thing to show up.

If you'd have told me five years ago I'd be excited about a calculator, I'd have laughed at you.

Funny how things work out. Who knew this stuff was so fun? Looking forward to seeing where this takes me.
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05-07-2019, 04:06 AM (This post was last modified: 05-07-2019 04:08 AM by rrpalma.)
Post: #2
RE: Just ordered a DM42
(05-06-2019 03:44 PM)Androsynth Wrote:  Hi all, I'm new here.

Long story short, I've decided to teach myself math. Had a pretty terrible math education (all of my worst teachers in high school and college were math teachers) and I find it annoying that I just don't 'get it'. So I decided to jump back in and learn it as a hobby. Well I needed a calculator right? So I got a TI 92+, which turned into a couple of Casios, a Prizm, and then an HP 50g and a Prime over the course of a couple of years. Hey, a hobby has to have gadgets, right? That's mostly thanks to random post results through google from here too.

While I enjoy all of them, one thing stuck out: the 50g. Having absolutely no experience with RPN/RPL, I was forced to learn it to use the damn thing... and I quickly found that RPN is the most helpful of the bunch when learning math, or at least, it is for me. Once I got it, I found it to be more of an ... extension of my brain I guess? Not only is it faster, it breaks down problems into component bits, forces me to 'walk' through them rather than just key them in, press a button, and see the answer. In the process, this often teaches me *where* I'm going wrong learning something. Super useful.

In the end, I ended up reading a bunch of stuff here about RPN, which led me to the HP 42s, and then, the new DM42. Given how much I'm learning with these things, I figure $200 on a new cal with pc-transfer capabilities was worth the expense... and now I'm waiting like an impatient child for the damn thing to show up.

If you'd have told me five years ago I'd be excited about a calculator, I'd have laughed at you.

Funny how things work out. Who knew this stuff was so fun? Looking forward to seeing where this takes me.

Nice post! I can empathize very much with it, since I’m going over all my engineering classes that I took when completing my degrees in CS and EE almost 30 yrs ago. It is quite an experience to go through all the theory behind with the aid of the newer HP and Swissmicros calculators (I used a 15C, 42S, 28S and 48SX while in school). I think (old) age and these tools give you a better perspective. I still don’t know which I prefer, though: the 50G or the Prime — both are outstanding machines — and so is the DM42.
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05-07-2019, 11:33 AM
Post: #3
RE: Just ordered a DM42
I've been using my DM42 for about a year and a half now. While there's certainly room for some improvement in the keyboard feel, the software and internals are top notch. Using RPN (particularly programming) is quite different from RPL - some things are easier, some are harder - so being good with both gives you a lot of flexibility.

Here's a non-exhaustive list of programs I keep on mine, in case you want ideas of what to do with it:

- Stack save/restore routines
- Probability programs (binomial distribution, negative binomial, Poisson, hypergeometric, etc.)
- Floor, ceiling, GCD, LCM
- Some matrix routines: column/row/whole matrix sums, min/max, sort
- Unit conversions (One that I wrote; easier to add new units than the traditional unit conversion programs that were floating around prior)
- Triangle solver
- Flag browser
- TVM/amortization package
- Many small solver programs for various equations
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05-07-2019, 01:49 PM (This post was last modified: 05-07-2019 01:50 PM by burkhard.)
Post: #4
RE: Just ordered a DM42
(05-06-2019 03:44 PM)Androsynth Wrote:  Hi all, I'm new here.
Long story short, I've decided to teach myself math...
<SNIP>

Great post! I enjoy hearing people excited about learning for its own sake, not because school, career, or some other necessity demands it.

For as much absolute crap as there is on the internet, it has indeed fostered a true renaissance of auto-didacticism. For that, I am grateful.
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05-07-2019, 02:17 PM
Post: #5
RE: Just ordered a DM42
(05-07-2019 01:49 PM)burkhard Wrote:  
(05-06-2019 03:44 PM)Androsynth Wrote:  Hi all, I'm new here.
Long story short, I've decided to teach myself math...
<SNIP>

Great post! I enjoy hearing people excited about learning for its own sake, not because school, career, or some other necessity demands it.

For as much absolute crap as there is on the internet, it has indeed fostered a true renaissance of auto-didacticism. For that, I am grateful.

Couldn’t agree more.
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05-07-2019, 02:56 PM (This post was last modified: 05-07-2019 02:58 PM by Androsynth.)
Post: #6
RE: Just ordered a DM42
Thanks for the responses, some good info here (thanks for the program suggestions Dave).

And yeah, I agree, the internet is fairly toxic these days, but it's also a great resource. My Dad was a teacher, and one thing he taught me was to love learning, and that learning did not require a school.

Diving back into math has made me realize just how bad our teaching of it is in general. If someone as a kid, had told me 'hey you love writing yeah? Well, math is the language you use to describe the universe around you' and let me actually play around with it, I would have had an entirely different experience, I think.

It's been interesting seeing the different design philosophies of Ti/Casio/HP in terms of the calculators. TI/Casio are designed (generally) to be easy to use, but at the same time, the actual steps involved in solving something are often obscured by the routine you're using to solve it. Type it in, hit enter, get an answer. Nothing wrong with that, if you use it to shorten time but not understanding.

HP (excluding the Prime, but that's another post) forces you to break down the problem you're solving into small pieces due to RPN, and your brain is what sorts/organizes the sequence. What I've found in learning math, is that if I can come up with an RPN/RPL program to do something, than I really do understand it. If I can't, very often I can see exactly where in the problem I'm making a mistake.

Doing rote exercises really isn't the best way to learn math, I'm finding. It's more playing around with it, and in the process, you learn how it expresses the world around you.

It's like I spent 12 years of school learning grammar, and only now am learning 'hey, you can write a story with this thing'
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05-09-2019, 08:57 AM
Post: #7
RE: Just ordered a DM42
(05-06-2019 03:44 PM)Androsynth Wrote:  In the end, I ended up reading a bunch of stuff here about RPN, which led me to the HP 42s, and then, the new DM42.

Thanks for sharing your thoughts here.
RPN can be addictive and i was introduced to it back in 1974 when a teacher brought one 35 to the electronics class.
Then i acquired a 25 and after that a 67 and a 25C and forgot my Casio fx-21 for good.

Concerning the DM42, while i am a big fan of the concept, i understand how hard is to get the physical keyboard right.
A few reports from buyers c9mment on some issues with the keys registration that are being addressed by the manufacturer.
When you get yours please share your experience with it.

Jose Mesquita
RadioMuseum.org member

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05-09-2019, 03:55 PM
Post: #8
RE: Just ordered a DM42
(05-09-2019 08:57 AM)jebem Wrote:  Concerning the DM42, while i am a big fan of the concept, i understand how hard is to get the physical keyboard right.
A few reports from buyers c9mment on some issues with the keys registration that are being addressed by the manufacturer.
When you get yours please share your experience with it.

Will do, I'm hoping I get it soon. I'd heard about the stiff keyboard issue, though it's unclear if that was more an early on thing that's been resolved, or an ongoing issue.

I'll post a review when I get it.
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05-09-2019, 04:19 PM
Post: #9
RE: Just ordered a DM42
(05-09-2019 03:55 PM)Androsynth Wrote:  Will do, I'm hoping I get it soon. I'd heard about the stiff keyboard issue, though it's unclear if that was more an early on thing that's been resolved, or an ongoing issue.

I'll post a review when I get it.

I'd definitely be interested in hearing about the keyboard feel on more recent models. I got mine in December 2017 from the first retail batch, and it was stiff to the point of being uncomfortable to use. You can improve it quite a bit by removing the PCB and flexing the keys slightly, but you need to be very conservative in doing this, or you'll end up having to epoxy worn out key legs like I've had to do a couple of times. But even still, the required force is very inconsistent from key to key. Honestly, I would have preferred if they had taken a less daring approach and just used a plain old rubber-dome keyboard like your average Casio. You've got much wider margins of error in getting those to feel good.
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05-09-2019, 07:26 PM (This post was last modified: 05-09-2019 07:28 PM by Zaphod.)
Post: #10
RE: Just ordered a DM42
Despite having bought a DM15 and DM41, I continue to hold off buying the DM42 based purely on the feedback on the keyboard problems.

I don’t want to buy into something with an inherent physical/design problem/weakness.... if they fix it consistently then I’m in.
The DM15 and 41 are good, I’d like the 42 to be the same.

What Dave is reporting is not good.
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05-09-2019, 07:54 PM
Post: #11
RE: Just ordered a DM42
(05-09-2019 07:26 PM)Zaphod Wrote:  Despite having bought a DM15 and DM41, I continue to hold off buying the DM42 based purely on the feedback on the keyboard problems.

I don’t want to buy into something with an inherent physical/design problem/weakness.... if they fix it consistently then I’m in.
The DM15 and 41 are good, I’d like the 42 to be the same.

What Dave is reporting is not good.

The 15L and 41L are definitely better than the 42, but even those are still a far cry from a real Voyager or 41C. These kinds of tactile keyboards are tough to get right, and not even every model/production run of HPs nailed it. And the LED TIs had pretty universally nasty keyboards too.

I like the DM42 for its software, and I use mine daily, but I've never been too fond of the keyboard (which I guess is a testament to how good Free42 is).
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05-10-2019, 08:34 AM
Post: #12
RE: Just ordered a DM42
(05-09-2019 07:54 PM)Dave Britten Wrote:  The 15L and 41L are definitely better than the 42, but even those are still a far cry from a real Voyager or 41C.

The problem is, anyone using a Voyager or a 41C (or 48G/S(X) for that matter) as a tactile feedback yardstick will never be happy with anything else. It just doesn't get any better than those. Even the Prime, good as it is, doesn't get anywhere near them.

(05-09-2019 07:54 PM)Dave Britten Wrote:  I like the DM42 for its software, and I use mine daily, but I've never been too fond of the keyboard (which I guess is a testament to how good Free42 is).

The DM42's keyboard does soften up with time and use. I have a production unit that I sometimes bring out but usually use my original beta unit from about 2 years ago. There is now a very marked difference between the two of them. The beta unit is now quite comfortable to use. Nowhere near as good as an original Pioneer/Voyager/whatever, but still pretty damned good all the same.
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05-10-2019, 11:15 AM
Post: #13
RE: Just ordered a DM42
(05-10-2019 08:34 AM)grsbanks Wrote:  
(05-09-2019 07:54 PM)Dave Britten Wrote:  The 15L and 41L are definitely better than the 42, but even those are still a far cry from a real Voyager or 41C.

The problem is, anyone using a Voyager or a 41C (or 48G/S(X) for that matter) as a tactile feedback yardstick will never be happy with anything else. It just doesn't get any better than those. Even the Prime, good as it is, doesn't get anywhere near them.

(05-09-2019 07:54 PM)Dave Britten Wrote:  I like the DM42 for its software, and I use mine daily, but I've never been too fond of the keyboard (which I guess is a testament to how good Free42 is).

The DM42's keyboard does soften up with time and use. I have a production unit that I sometimes bring out but usually use my original beta unit from about 2 years ago. There is now a very marked difference between the two of them. The beta unit is now quite comfortable to use. Nowhere near as good as an original Pioneer/Voyager/whatever, but still pretty damned good all the same.

I've got a Prime, and I can honestly say that the keys feel much better than the 3 SM calculators I own, and it's certainly much closer to the gold standard of the 41C. The 15L and 41L are a bit stiffer than they should be, but reasonably consistent and responsive. The 42 is much too stiff, even after over 1.5 years of use and deliberate key loosening, and the feel is very inconsistent from key to key. But I've at least gotten it to the point that I can live with it, despite not really liking the keyboard. I think it's a sign that SM needs to scrap their keyboard design if they require nearly 2 years of break-in (and pieces of cut-up paper stuffed under the Enter key) to arrive at something tolerable.

Short version: The DM42 is a lovely calculator, that's really held back by its keyboard which prevents you from doing any fast operation.
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05-10-2019, 06:22 PM
Post: #14
RE: Just ordered a DM42
It’s that micro-dimensional interface between the bottom of the keys and the top of the domes that makes all the difference.

That needs to be addressed across the whole keyboard area, a tenth of a millimetre variance makes a huge difference with ‘across the keyboard’ slickness.
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05-10-2019, 07:06 PM
Post: #15
RE: Just ordered a DM42
I love everything about mine. I do not understand the micro-complaining. Cheers!

R Nav
Clinton Twp, MI

28c
28s
48sx
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17bii
33s
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Prime
wp34s
DM42 (daily user)
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05-10-2019, 10:15 PM
Post: #16
RE: Just ordered a DM42
(05-07-2019 02:17 PM)rrpalma Wrote:  
(05-07-2019 01:49 PM)burkhard Wrote:  Great post! I enjoy hearing people excited about learning for its own sake, not because school, career, or some other necessity demands it.

For as much absolute crap as there is on the internet, it has indeed fostered a true renaissance of auto-didacticism. For that, I am grateful.

Couldn’t agree more.

I completely third that! I also came back to maths thanks to a HP-29C!
Thanks for your post and welcome!
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05-31-2019, 08:59 AM (This post was last modified: 05-31-2019 09:25 AM by Matthias D..)
Post: #17
RE: Just ordered a DM42
Do you have to have a calculator to learn math?

WP 34 S
HP 11, 20 s, 25, 27 s, 28C, 32 SII, 33 s, 42 s, 45
Casio fx 9860G slim, 7000G, 3100, 991 MS, 350 W, 602, 600, 502, 401, 82solar, H1
A bunch of Sharps, Tis and a lot of miscellaneous ones.
Last but not least: slide rules in any shape and form.

(Inserting a Smiley with sunglasses didn´t work)

Yours!
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05-31-2019, 12:05 PM
Post: #18
RE: Just ordered a DM42
(05-31-2019 08:59 AM)Matthias D. Wrote:  Do you have to have a calculator to learn math?

WP 34 S
HP 11, 20 s, 25, 27 s, 28C, 32 SII, 33 s, 42 s, 45
Casio fx 9860G slim, 7000G, 3100, 991 MS, 350 W, 602, 600, 502, 401, 82solar, H1
A bunch of Sharps, Tis and a lot of miscellaneous ones.
Last but not least: slide rules in any shape and form.

(Inserting a Smiley with sunglasses didn´t work)

Yours!

Cool

What? Wink

Greetings,
    Massimo

-+×÷ ↔ left is right and right is wrong
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05-31-2019, 12:26 PM (This post was last modified: 05-31-2019 12:27 PM by Thomas Okken.)
Post: #19
RE: Just ordered a DM42
Hmm. This suggests that you should just be able to insert standard Unicode emoji, but I just tried the one with the sunglasses, and while it did show up in the message preview, it did not show up when I hit Post Reply.

smile : ?
sunglasses : ?
scream : ?
pile of poo : ?

Nope. Looks like the forum turns them into question marks when you hit Post. Not a rendering issue but an actual filter.
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05-31-2019, 12:41 PM
Post: #20
RE: Just ordered a DM42
See here:
https://www.hpmuseum.org/forum/thread-10...l#pid95051

--Bob Prosperi
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