DM15L keyboard response?

Discussion of hardware issues related to the DM1x/DM41. Please ensure that you specifiy whether the issue is related to a credit card size unit or a "Voyager" unit (DM1xL/DM41L).
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fcrvincent
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Location: UK

DM15L keyboard response?

Post by fcrvincent » Tue Jan 29, 2019 5:58 pm

An amazon verified purchaser of a DM15L on 11 Jan 2018 reported that ".. I found that if you press the keys too fast, the numbers won't register which leads to mistakes in my calculations. I have to slow down and recheck everything I do.."

Also I found the the following comment on http://cgi.linuxfocus.org/~guido/hp_calc/: ".. The original HP keyboard is better but the DM-15L keyboard is totally usable altought it is possible to presss a key without it registering which does not happen on original HP-15c calculators.." (serial 00554).

Is this something that owners of the DM15L on this forum have experienced too?

Just a bit concerned before taking the plunge on one as the physical keyboard is probably 99% of the reason to buy a DM15L (vs an HP-15C smartphone app).

Thanks for your inputs

Dave Britten
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Re: DM15L keyboard response?

Post by Dave Britten » Wed Jan 30, 2019 7:41 pm

I don't have a 15L, but I have a 16L and 41L, and the only way I can get them to miss keystrokes when typing fast is by slowing the CPU down to 12 MHz. It runs at 48 MHz by default, and I don't have any problems with responsiveness.

grsbanks
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Re: DM15L keyboard response?

Post by grsbanks » Wed Jan 30, 2019 9:10 pm

Just to confirm, if it wasn't obvious from Dave's comment, that the DM11L, 12L, 15L, 16L and 41L all run on identical PCBs. The only differences between them are the housing, keys and firmware.
Not SwissMicros staff, just an enthusiast.

fcrvincent
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Joined: Wed Dec 05, 2018 8:18 pm
Location: UK

Re: DM15L keyboard response?

Post by fcrvincent » Thu Jan 31, 2019 10:36 am

Thanks for your feedback.

Interesting point about the keyboard response being good at 48MHz. May be something to improve in next gen DM1xL devices (or in the firmware?). The nutcore processor of the original HP-15C runs at less than 400KHz (that is 30 times slower than the DM1xL at 12MHz) and registers all keys reliably.

Running the unit at 48Mhz may be a solution but is likely to shorten battery life significantly (when the calculator is on).

cdmackay
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Re: DM15L keyboard response?

Post by cdmackay » Thu Jan 31, 2019 10:26 pm

fcrvincent wrote:
Thu Jan 31, 2019 10:36 am
Running the unit at 48Mhz may be a solution but is likely to shorten battery life significantly (when the calculator is on).
This was discussed in another thread recently, and the outcome wasn't entirely clear. Since the calculator probably uses a similar amount of energy to perform an operation, regardless of processor clock frequency (since at 4 times the speed it may complete the operation up to 4 times quicker), and because the processor goes into low-power mode when you're not pressing keys or running programs, it's not clear that it makes a big difference. The LCD will be on longer, but that takes a fraction of the current so can be ignored for this comparison.

I'd like to hear a definitive answer (which this isn't!).
Cambridge, UK
41CL, 12C/15C, DM15/16, 71B, 17B, 28S, DM42, 48GX, 17bII+, 50g (& newRPL), 35s, 30b (WP 34S), Prime G2
& Casios, Rockwell 18R :)

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