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Tell me about the DM42
12-19-2017, 10:06 PM
Post: #1
Tell me about the DM42
How do you like the DM42? If it is so similar to HP 42S, then what is the large screen for? Is it more of a graphing calculator is it an extended stack? How do you like the build quality?

Oh, and is there some sort of instruction manual out there? (I don't even have one for my HP 42S)

Thanks!
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12-19-2017, 10:56 PM
Post: #2
RE: Tell me about the DM42
It's a great reimagining of the 42S. You might see some reports of graphing capability, but it's not a new built-in feature. The 42S always had PIXEL and AGRAPH commands which could make rudimentary plots in the 131x61 display. What's changed is that a 400x240 pixel display can be addressed with the same RPN programs that used to be limited to 131x61. Swissmicros left a program called "DJPLOT" in the included set of loadable programs so you can easily play with the new real estate. I'd say the display is the best part of the package. You really have to see it in person. There are new options for displaying the whole stack and the LastX (or alpha) register. You can play with font size and type too.

Thomas Okken's Free42 reproduces 99.999% of what the 42S does but much faster. I would have said 100%, but a few obscure differences have been found. Look up Free42's user manual as well as the original 42S user manual. External to Free42, the DM42 has an OS that controls features of the display and access to a 6MB FAT flash drive. The user manual for that stuff is apparently built in to the calculator (I haven't seen it myself in my beta unit). But look here: Online Manual

You get IR printing like the 42S, but you also get the much welcome USB file transfer ability. The USB port can also power the DM42 to save on battery consumption and allows for firmware updates. You get new alpha-input modes while retaining the classic menu alpha entry.

The build quality is outstanding where it really counts: looking inside for the first time at the PCB was a delight. The internals are rock solid. Some issues were identified with the beta hardware that I think are mostly fixed in the production units: bezel looseness, key feel and registering, USB port alignment. Those kinds of issues are less worrisome, however when Swissmicros offers suggestions for us to fix them ourselves or offers replacements. I don't feel nervous about taking the DM42 apart because it's clearly built to be opened up. It's not at all like a 42S that is heat welded shut and risky to open.
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12-19-2017, 11:42 PM
Post: #3
RE: Tell me about the DM42
(12-19-2017 10:56 PM)revwillie Wrote:  Swissmicros left a program called "DJPLOT" in the included set of loadable programs so you can easily play with the new real estate.

I don't have DJPLOT on my DM42 production unit. Can you share it?
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12-20-2017, 12:15 AM (This post was last modified: 12-20-2017 12:18 AM by Logan.)
Post: #4
RE: Tell me about the DM42
As someone who really enjoyed the 42S (I mean, really enjoyed it) I can say that this is almost unbelievable in how much I'm enjoying the DM42.

The screen does show all of the stack yes, which is great, but where the extra real estate really shines (for me) is in the programming. I can now see 8 lines of code at a time and it scrolls beautifully. No video I've seen does justice to how nice the screen looks in person.

The calculator does include a quick-start guide on the calculator itself, which is very well-written, and the large screen works nicely for that too Smile

In addition to tons of memory, and the ability to save and load programs from USB (hallelujah), it also has the surprising ability to save states. In other words, say I'm working in a particular environment and put on my financial hat for a moment. I can set up a custom menu and set of programs, the display settings, etc. and then save that configuration! Later I put on my EE hat and want to do some matrices, power equations, and customize everything to be set up to display in engineering mode, have my programs in the right spots (and don't clutter everything up with unnecessary programs for that application), etc. I can save that configuration too and then any time I need to switch hats, I can load the configuration I want and it's all set up exactly how I wanted it. I love this.

Or if I just want everything in one big messy spot, I set up a "General" state for myself where I can mess around.

One other thing you may have noticed, is there is an extra row of keys at the top specifically dedicated to the soft keys. This means you can have a menu open and also use the 1/x, sqrt, log, etc. at the same time. I knew that would be nice...but it's really nice.
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12-20-2017, 06:30 AM
Post: #5
RE: Tell me about the DM42
(12-19-2017 11:42 PM)Didier Lachieze Wrote:  
(12-19-2017 10:56 PM)revwillie Wrote:  Swissmicros left a program called "DJPLOT" in the included set of loadable programs so you can easily play with the new real estate.

I don't have DJPLOT on my DM42 production unit. Can you share it?

There's an online copy of the fat disk linked from the relevant part of the manual. Sorry I just tried to paste the link using my phone and I'm not sure why it didn't work.
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12-20-2017, 08:26 AM
Post: #6
RE: Tell me about the DM42
(12-19-2017 10:56 PM)revwillie Wrote:  Swissmicros left a program called "DJPLOT" in the included set of loadable programs so you can easily play with the new real estate.

I'm glad people are enjoying DJPLOT but please bear in mind that I wrote this during the testing phase so that we could try out the new roomy screen real estate before letting the beta testers loose on it. I wrote it double-quick, and its purpose was to test the PIXEL command (there's another one in there somewhere that tests AGRAPH and the interaction with flags 34/35), not to make something bullet-proof. Consequently, there's little to no error checking in there so expect the unexpected Smile
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12-20-2017, 09:55 AM
Post: #7
RE: Tell me about the DM42
(12-20-2017 06:30 AM)revwillie Wrote:  
(12-19-2017 11:42 PM)Didier Lachieze Wrote:  I don't have DJPLOT on my DM42 production unit. Can you share it?

There's an online copy of the fat disk linked from the relevant part of the manual. Sorry I just tried to paste the link using my phone and I'm not sure why it didn't work.

Thanks. I've found it. It didn't thought that the pre-filled FAT disk contents linked in the on-line manual would be different than was loaded on my production DM42.
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12-20-2017, 12:22 PM
Post: #8
RE: Tell me about the DM42
(12-19-2017 11:42 PM)Didier Lachieze Wrote:  
(12-19-2017 10:56 PM)revwillie Wrote:  Swissmicros left a program called "DJPLOT" in the included set of loadable programs so you can easily play with the new real estate.

I don't have DJPLOT on my DM42 production unit. Can you share it?

I don't have it on mine, either.

Tom L

I never knew my mother was such an animal lover. When the doctor told her the rabbit died, she went into shock!
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12-20-2017, 12:36 PM
Post: #9
RE: Tell me about the DM42
My quick list of thoughts so far:

- The build quality is great. This thing feels really solid (especially the glass screen cover).
- It runs very fast compared to a real 42S.
- The screen contrast is excellent, and having full-screen program editing is awesome.
- Available RAM is about 10 times that of a real 42S.
- The approach to using the ~6 MB flash storage works well (import/export individual programs, or save/load entire RAM backups).
- The keys are much too stiff. Think 49G, but thankfully they're not rubber keys, so you don't have to deal with them buckling under the force.
- Two of the keys on mine (2 and +) were a bit picky about responding; peeling up the keyboard layer for a quick cleaning seemed to fix it.
- I like that it uses a CR2032 rather than a special rechargeable pack. Makes it more future-proof.
- The multi-line stack layouts are very nice, though I'm not sure why they don't have an option for XYZTLA. You either get L or Alpha, not both.
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12-20-2017, 12:43 PM
Post: #10
RE: Tell me about the DM42
One thing I really like about the DM42 is the annunciators for user flags 00-10.
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12-20-2017, 01:26 PM
Post: #11
RE: Tell me about the DM42
(12-20-2017 12:36 PM)Dave Britten Wrote:  - Available RAM is about 10 times that of a real 42S.

In terms of bytes, yes, but bear in mind that Free42 uses memory at about twice the rate of a real HP-42S, so effectively you get about 5 Times the RAM.
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12-20-2017, 01:41 PM
Post: #12
RE: Tell me about the DM42
(12-20-2017 01:26 PM)Thomas Okken Wrote:  
(12-20-2017 12:36 PM)Dave Britten Wrote:  - Available RAM is about 10 times that of a real 42S.

In terms of bytes, yes, but bear in mind that Free42 uses memory at about twice the rate of a real HP-42S, so effectively you get about 5 Times the RAM.

Oh yeah, good point. Does that apply to program steps, or just data/numeric constants?
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12-20-2017, 02:23 PM
Post: #13
RE: Tell me about the DM42
(12-20-2017 01:41 PM)Dave Britten Wrote:  
(12-20-2017 01:26 PM)Thomas Okken Wrote:  In terms of bytes, yes, but bear in mind that Free42 uses memory at about twice the rate of a real HP-42S, so effectively you get about 5 Times the RAM.

Oh yeah, good point. Does that apply to program steps, or just data/numeric constants?

Real and complex numbers stored in registers or variables use twice what they use on the HP-42S. The same obviously goes for real and complex matrices.

As far as program bytes are concerned, Free42 uses up the same amount of space as the HP-42S with the exception of very slightly different storage of numerical literals in some cases.
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12-20-2017, 03:46 PM
Post: #14
RE: Tell me about the DM42
(12-20-2017 02:23 PM)grsbanks Wrote:  As far as program bytes are concerned, Free42 uses up the same amount of space as the HP-42S with the exception of very slightly different storage of numerical literals in some cases.

No, Free42 reports the same program sizes as the HP-42S, but it uses roughly double the space for program storage.

The shortest instructions on the 42S take up one byte, two in Free42; most 42S instructions with arguments take up two bytes, four in Free42; embedded GTO and XEQ offsets are 8 or 12 bits on the 42S, 32 bits in Free42; numbers are stored as a sequence of digits on the 42S, and in native integer or floating-point format in Free42, which can be shorter but is usually longer.

Most Free42 users are probably unaware of all this, since programs are imported and exported in the same "raw" format that Emu42 uses, which is the format in which the real HP-42S stores programs... but Free42 does this by converting between that format and its totally different internal format whenever it imports or exports programs.

Early versions of Free42 actually offered the choice between reporting true program size and HP-42S-compatible program size. I ended up dropping the "true size" option because, on platforms with megabytes of RAM, the actual size of programs didn't matter, while the 42S-compatible byte count still provided a useful, if weak, integrity check (except for the 1000 turning into 1E3 thing Free42 does, which grsbanks alluded to). Given that memory is much more limited in the DM42 than on a PC or smartphone, and it seems entirely possible that some people might fill it up, perhaps I should restore the "actual program size" option.
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12-20-2017, 03:50 PM
Post: #15
RE: Tell me about the DM42
(12-20-2017 03:46 PM)Thomas Okken Wrote:  Most Free42 users are probably unaware of all this, since programs are imported and exported in the same "raw" format that Emu42 uses, which is the format in which the real HP-42S stores programs... but Free42 does this by converting between that format and its totally different internal format whenever it imports or exports programs.

Thanks for the info. I was unaware of that and stand corrected.
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12-20-2017, 04:03 PM
Post: #16
RE: Tell me about the DM42
(12-20-2017 12:36 PM)Dave Britten Wrote:  My quick list of thoughts so far:

- The build quality is great. This thing feels really solid (especially the glass screen cover).
- It runs very fast compared to a real 42S.
- The screen contrast is excellent, and having full-screen program editing is awesome.
- Available RAM is about 10 times that of a real 42S.
- The approach to using the ~6 MB flash storage works well (import/export individual programs, or save/load entire RAM backups).
- The keys are much too stiff. Think 49G, but thankfully they're not rubber keys, so you don't have to deal with them buckling under the force.
- Two of the keys on mine (2 and +) were a bit picky about responding; peeling up the keyboard layer for a quick cleaning seemed to fix it.
- I like that it uses a CR2032 rather than a special rechargeable pack. Makes it more future-proof.
- The multi-line stack layouts are very nice, though I'm not sure why they don't have an option for XYZTLA. You either get L or Alpha, not both.

Thanks for all the info! What you say about the buttons give me a bit of a pause, since I have recently gone through two calculators with button issues. I guess I am a bit fed up with that right now Smile
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12-20-2017, 07:45 PM
Post: #17
RE: Tell me about the DM42
(12-20-2017 03:46 PM)Thomas Okken Wrote:  Most Free42 users are probably unaware of all this, since programs are imported and exported in the same "raw" format that Emu42 uses, which is the format in which the real HP-42S stores programs... but Free42 does this by converting between that format and its totally different internal format whenever it imports or exports programs.


Gene: Wish list... :-)

1) So what about some sort of translation between HP 41 raw formats into Free42 / DM-42 formats?

2) The HP 42S CUSTOM keyboard of three rows of menu labels always irked me. Any chance for a USER keyboard for every key?

3) Any chance at all for getting HP 41 rom images put in and running things from them?


Hey, I DID say it was a wish list. Thanks Thomas for all you have done with all of this.
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12-20-2017, 08:20 PM
Post: #18
RE: Tell me about the DM42
(12-20-2017 07:45 PM)Gene Wrote:  1) So what about some sort of translation between HP 41 raw formats into Free42 / DM-42 formats?

What translation? The 41 and 42S already use the same format. As long as you avoid 41- and 42S-specific functionality, you can copy programs between the two to your heart's content.

(12-20-2017 07:45 PM)Gene Wrote:  3) Any chance at all for getting HP 41 rom images put in and running things from them?

The only way to run HP-41 Mcode is on a hardware-level HP-41 emulator (or a real 41, duh). Free42 will never support this, and I dare say neither will Emu42.
If, on the other hand, you want to run user code from HP-41 ROM images, take a look a the rom2raw program on my web site.
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12-21-2017, 04:00 AM
Post: #19
RE: Tell me about the DM42
Great. If you can't have everything :-) you can certainly be thankful for some good things here! ty
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12-21-2017, 07:45 AM
Post: #20
RE: Tell me about the DM42
I'm afraid the DM42 is not compatible with the 42S: it shows lowercase characters in the menus!!

;-)
Werner
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