DM42 News

[DavidM]

(02-14-2018 04:50 AM)John Cadick Wrote:  

(02-13-2018 08:14 PM)martinot Wrote:  Great!

I just ordered a brand new 82240B to use with both my 50g and DM42.

I did not think that the 50g has a compatible IR? Is there a mod that I missed?

John

No modifications required. But the 50g's IR output is very weak compared to other models, and everything has to be "just right" for consistent results. I find that I have to keep the 50g within about an inch of the printer, carefully aligned, and sometimes I have to block out extraneous light as well. If printing GROBs or large amounts of text, it's also easy for the calculator to fill the printer's buffer. Changing the DELAY setting can help with this. If printing GROBs, I set a DELAY factor of 1.05 for my particular printer. That can slow down regular text printing, though, so experimentation may be needed for best results. EDIT: Hadn't finished my coffee before typing that. It's the other way around... setting the DELAY to 1.05 is useful when printing lots of text, but I set it to 0 for printing GROBs (which is already a slow process, and DELAY would make it even more painful).

[rprosperi]

(02-14-2018 03:49 PM)DavidM Wrote:  But the 50g's IR output is very weak compared to other models, and everything has to be "just right" for consistent results. I find that I have to keep the 50g within about an inch of the printer, carefully aligned, and sometimes I have to block out extraneous light as well.

HP deliberately limited the IR x-mit power to require devices be very close to communicate as schools were complaining about students "beaming" data back and forth. Though the administrators no doubt feared that test questions and/or answers were being sent, in truth it was much more likely to be chatting than cheating.

This is also the same reason the Prime has no IR, unit-to-unit is disabled, and they offer the proprietary wireless solution for schools.

[John Cadick]

Thank you Salvo and David. Good to know. The YouTube video is good primer. Think I’ll play with my 50g and printer for a while.

[Andreas]

My DM42 arrived yesterday and I was (and still am) eager to play with it. What can I say? This little machine is a fine example of a rock solid Swiss product, which looks and feels like it could hold forever.
David and Michael did a great job putting Thomas' software into modern hardware, thus assuring continued and enhanced use of one of the best calculators ever built.
Having tried Free42 for years on various hosts I'm very happy that a dedicated home for this software platform is available now - there's nothing like real keys when it comes to calculators. And the big and clear display is a huge advantage to the original one.

Now I only have to wait three more months before I really can use my DM42, since it will be a birthday present.

Andreas

[polbit]

(02-18-2018 06:48 PM)Andreas Wrote:  Now I only have to wait three more months before I really can use my DM42, since it will be a birthday present.

Andreas

That is self-control that I'm certainly not capable of!

[4ster]

(02-18-2018 08:29 PM)polbit Wrote:  

(02-18-2018 06:48 PM)Andreas Wrote:  Now I only have to wait three more months before I really can use my DM42, since it will be a birthday present.

Andreas

That is self-control that I'm certainly not capable of!

Heck, I'm already using my 2019 birthday present to myself!

[Andreas]

(02-18-2018 08:29 PM)polbit Wrote:  

(02-18-2018 06:48 PM)Andreas Wrote:  Now I only have to wait three more months before I really can use my DM42, since it will be a birthday present.

Andreas

That is self-control that I'm certainly not capable of!

This is true, it is very hard in fact. I still remember the scent of the SR-56 (HPs were too expansive at the time), its cover and manuals, which was a christmas present 42 years ago.
Secretly, when my parents where not at home, I went to its hiding place just to touch the device and inhale the wonderful scent.

By the way, with renewed batteries the SR-56 ist still working with all led segments bright and key clicks nearly as new despite heavy use over its first years.

[eulerfan]

Hi all, I've been using Okken's Free42 for a long time, and am looking into getting a DM42. But before I do, I'd like to know what battery it uses and how long the battery lasts. I think the DM42 has been out long enough that plenty of people have had to replace its battery(ies).

[Thomas Okken]

(03-10-2018 08:25 PM)eulerfan Wrote:  Hi all, I've been using Okken's Free42 for a long time, and am looking into getting a DM42. But before I do, I'd like to know what battery it uses and how long the battery lasts. I think the DM42 has been out long enough that plenty of people have had to replace its battery(ies).

Please, call me Thomas. Or Mr. Okken, if you prefer last names.

The DM42 uses a single CR2032. From what I hear, worst-case life is about three days, while running programs non-stop; under continuous normal use, where the screen is on but the calculator is mostly idle, it lasts for several weeks, and on standby, several years. If you expect to use it normally, you should be able to go several months on one battery.

You may also want to check the SwissMicros forum: https://forum.swissmicros.com/ -- this topic has been covered in great detail over there.

[toml_12953]

(03-10-2018 08:25 PM)eulerfan Wrote:  Hi all, I've been using Okken's Free42 for a long time, and am looking into getting a DM42. But before I do, I'd like to know what battery it uses and how long the battery lasts. I think the DM42 has been out long enough that plenty of people have had to replace its battery(ies).

I haven't heard of anyone having to replace the battery (a CR-2032 coin cell) yet. That doesn't mean no one has, just that I haven't heard of it. I have both a beta unit and a shipping unit and neither has needed a battery yet. I use min about 3-4 hours a day.

[eulerfan]

(03-11-2018 02:07 AM)Thomas Okken Wrote:  

(03-10-2018 08:25 PM)eulerfan Wrote:  Hi all, I've been using Okken's Free42 for a long time, and am looking into getting a DM42. But before I do, I'd like to know what battery it uses and how long the battery lasts. I think the DM42 has been out long enough that plenty of people have had to replace its battery(ies).

Please, call me Thomas. Or Mr. Okken, if you prefer last names.

Sorry, I didn't know I was being offensive. I just wanted to be specific that I was using your Free42.

Quote:The DM42 uses a single CR2032. From what I hear, worst-case life is about three days, while running programs non-stop; under continuous normal use, where the screen is on but the calculator is mostly idle, it lasts for several weeks, and on standby, several years. If you expect to use it normally, you should be able to go several months on one battery.

You may also want to check the SwissMicros forum: https://forum.swissmicros.com/ -- this topic has been covered in great detail over there.

Thanks. The battery on my HP-42S was a real concern as the calculator wouldn't let me back up my programs. I think several years on standby for the DM42, plus a way to save some files to my PC, will be perfect.

[eulerfan]

(03-11-2018 02:08 AM)toml_12953 Wrote:  

(03-10-2018 08:25 PM)eulerfan Wrote:  Hi all, I've been using Okken's Free42 for a long time, and am looking into getting a DM42. But before I do, I'd like to know what battery it uses and how long the battery lasts. I think the DM42 has been out long enough that plenty of people have had to replace its battery(ies).

I haven't heard of anyone having to replace the battery (a CR-2032 coin cell) yet. That doesn't mean no one has, just that I haven't heard of it. I have both a beta unit and a shipping unit and neither has needed a battery yet. I use min about 3-4 hours a day.

That's good news, thanks.

[Logan]

I too have had mine since mid-December and have been using it daily, entering tons of programs, saving and loading states. It goes with me everywhere and I haven't yet seen an appreciable drop in battery voltage. I anticipate it will last quite a while. Certainly longer than any of my graphing calculators, and backing up programs is as simple as connecting a USB cable and dragging and dropping with a second or two to transfer files. Loving it.

[Michael de Estrada]

Keep in mind that you can also power the DM42 from a USB cable, during which time the battery will not be consumed. The calculator will also run faster when powered by USB. Finally, you can back up memory in the calculator’s flash drive, so if the battery happens to go dead and you didn’t back up to an external hard drive, you won’t lose your programs and data. Really, the DM42 has addressed all the major shortcomings of the HP 42s. I have also had my DM42 for nearly three months, and am still using the original battery. Just remember to save the calculator state before you replace the battery.

[eulerfan]

(03-12-2018 01:39 PM)Logan Wrote:  I too have had mine since mid-December and have been using it daily, entering tons of programs, saving and loading states. It goes with me everywhere and I haven't yet seen an appreciable drop in battery voltage. I anticipate it will last quite a while. Certainly longer than any of my graphing calculators,

Excellent, thanks.

Quote:and backing up programs is as simple as connecting a USB cable and dragging and dropping with a second or two to transfer files. Loving it.

Great! Whenever I changed the batteries on my 42s, my programs always vanished. It's been years, so I forget whether the calculator had provisions for sustaining the memory while the batteries were being changed. Or maybe I was just too slow at swapping the button cells. Whatever, my programs were gone, and I got really tired of reentering them (they were quite large). Looks like the DM42 has fixed that.

[grsbanks]

(03-12-2018 04:21 PM)eulerfan Wrote:  just too slow at swapping the button cells.

If you replace them one at a time you can get away with it, but you have to be quick.

(03-12-2018 04:21 PM)eulerfan Wrote:  Whatever, my programs were gone, and I got really tired of reentering them (they were quite large). Looks like the DM42 has fixed that.

Provided you save the machine state to flash before yoiking the old battery out! And you have to do that before the battery voltage drops below 2.2V or it won't allow you to write to flash. In that case, just connect it to USB and then you can save the machine state.

[eulerfan]

(03-12-2018 02:43 PM)Michael de Estrada Wrote:  Keep in mind that you can also power the DM42 from a USB cable, during which time the battery will not be consumed.

Good to know.

Quote:The calculator will also run faster when powered by USB.

Nice.

Quote:Finally, you can back up memory in the calculator’s flash drive, so if the battery happens to go dead and you didn’t back up to an external hard drive, you won’t lose your programs and data.

Backing up to flash should be even more convenient than using the USB cable.

I just had a thought. I suppose the operating system (Free42 + device drivers) is also stored on that flash drive. Is there a way to do a checksum or CRC on the OS to verify that it's intact? Does the DM42 have a reset button that forces a reboot?

Quote:Really, the DM42 has addressed all the major shortcomings of the HP 42s.

Looks like it!

Quote:I have also had my DM42 for nearly three months, and am still using the original battery. Just remember to save the calculator state before you replace the battery.

I'll do that.

[grsbanks]

(03-12-2018 04:37 PM)eulerfan Wrote:  I just had a thought. I suppose the operating system (Free42 + device drivers) is also stored on that flash drive.

There are two flash ROMs in the DM42.

There is one of 1MB within the STM32L476 main CPU and there is an external 8MB QSPI chip.

The O/S and all the executable code is in the STM32L476. The QSPI chip is divided into a zone of 2MB and the remainder of 6MB. The 2MB portion contains tables used by the Intel Decimal Floating Point library and other bits of static data. The 6MB chunk is the flash drive that you see on your computer when you plug the DM42 into your USB socket and activate "FAT Disk mode".

(03-12-2018 04:37 PM)eulerfan Wrote:  Is there a way to do a checksum or CRC on the OS to verify that it's intact?

Not on the O/S in the STM32L476, but a checksum of the QSPI's 2MB zone is performed at every machine reset to ensure that you have the right version of the QSPI contents to go with your version of the Intel library etc. If there is a mismatch then you are prompted to flash the correct QSPI version.

(03-12-2018 04:37 PM)eulerfan Wrote:  Does the DM42 have a reset button that forces a reboot?

Look on the back of the calculator

[Paul Dale]

(03-12-2018 06:43 PM)grsbanks Wrote:  The 2MB portion contains tables used by the Intel Decimal Floating Point library and other bits of static data.

I did wonder where these ended up. The heavy reliance on tables means fast execution but large size which isn't always the best trade off in embedded devices. Intel's library also uses the equivalent binary operations to provide starting points. This means they'll typically be more accurate than required and thus slower to compute and even more space is consumed.


Pauli

[eulerfan]

(03-12-2018 04:26 PM)grsbanks Wrote:  

(03-12-2018 04:21 PM)eulerfan Wrote:  just too slow at swapping the button cells.

If you replace them one at a time you can get away with it, but you have to be quick.

That was my thinking too. I guess I wasn't quick enough.

Quote:

(03-12-2018 04:21 PM)eulerfan Wrote:  Whatever, my programs were gone, and I got really tired of reentering them (they were quite large). Looks like the DM42 has fixed that.

Provided you save the machine state to flash before yoiking the old battery out!

That makes sense.

Quote:And you have to do that before the battery voltage drops below 2.2V or it won't allow you to write to flash. In that case, just connect it to USB and then you can save the machine state.

I'll remember that, thanks.