HP Forum Archive 17

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41s Message #1 Posted by Hugh Evans on 1 June 2007, 12:22 p.m. Alright, so the 35s isn't even out yet, but even so it's a good platform for making modifications partially due to its' thickness. Here is my proposal of what we should do with it to make it better: Gut the electronics, keep the LCD, make a new PCB with either an arm7 or arm9TDMI, give it about 512KB of SRAM, USB, SD/MMC card support, and load it with the command set of the 41c. We can give the keyboard a new set of labels with an overlay and silk-screen the keys. If there's enough room it could even be fun to add 2 to 4 41c expansion module sockets. Since the enclosure will be ready to go, producing the rest of a modification kit will cost under $50. Anyone interested in bringing back the 41 in a more powerful form? -Hugh

Re: 41s Message #2 Posted by cfh on 1 June 2007, 12:31 p.m., in response to message #1 by Hugh Evans Hmm, Yes, but why not an HP42sx - Whooo haaaa! cheers /cfh

Re: 41s Message #3 Posted by Hugh Evans on 1 June 2007, 12:39 p.m., in response to message #2 by cfh The form factor of the 35s is a better match for the 41. I think one of the products from OpenRPN will satisfy your desire for a 42sx.

Re: 41s Message #4 Posted by cfh on 1 June 2007, 12:44 p.m., in response to message #3 by Hugh Evans Nice pic! But can we assume it will materialize? And when? /cfh

Re: 41s Message #5 Posted by Miguel Toro on 1 June 2007, 3:12 p.m., in response to message #3 by Hugh Evans I want my OpenRPN 42sx!!!! :-)

Re: 41s Message #6 Posted by DaveJ on 1 June 2007, 7:09 p.m., in response to message #1 by Hugh Evans I have never opened a 33s, on which the 35s hardware is presumably based. Does the keyboard have it's own PCB, or is it integral to the main PCB? (making the job a bit messier) Anyone got any internal photos of the 33s? Dave.

Re: 41s Message #7 Posted by Gerson W. Barbosa on 1 June 2007, 8:55 p.m., in response to message #6 by DaveJ Open_33s.JPG (167 KB)

Re: 41s Message #8 Posted by Walter B on 1 June 2007, 11:49 p.m., in response to message #7 by Gerson W. Barbosa Oh, oh, old HP calcs look a lot cleaner!

Re: 41s Message #9 Posted by Hugh Evans on 1 June 2007, 10:24 p.m., in response to message #6 by DaveJ Judging by the specs of the 35s, we're going to have tons of room to work with inside. There are enough engineers around here to create a standard modification procedure. Even if it entails major surgery we can figure it out. I'm just happy to have a good enclosure and set of keys to work with.

Re: 41s Message #10 Posted by Don Williams on 1 June 2007, 9:09 p.m., in response to message #1 by Hugh Evans While everyone else is going "gaga" over the new 35S, I am a little disappointed in the "expected" lack of I/O. So any attempt to create it , however the means, would interest me.

Re: 41s Message #11 Posted by Hugh Evans on 1 June 2007, 11:31 p.m., in response to message #10 by Don Williams I suspect you are not alone in your opinion. I'm viewing the 35s as a nice enclosure, set of keys, and lcd we can use to make something much better. Making electronics is much easier than the other parts. This has the potential to be an exceptionally cool project.

Re: 41s Message #12 Posted by Bill Wiese on 2 June 2007, 12:35 a.m., in response to message #11 by Hugh Evans There's really little need for the horsepower of an ARM. Packaging suitable for the casing, as well as power considerations and I/O appropriate for the existing HP LCD should be chosen first. A TI MSP430 or PIC or other CPU along with an SPI serial flash memory (up to 2MB) and SPI serial RAM can work just fine to emulate an improved existing calc. I'm betting the HP 35S uses low-cost COB (chip-on-board - chip bonded to PCB, covered with a glop of silicone) mounting, and that the PCB is heat-staked to the case. A thin 'sub-PCB' will prob need to be fabricated, and existing CPU disabled somehow (foil cuts?). Tapping into PCB where exsiting chip is will be a bitch - there may be better places (test connector?) to get access without doing a whole new main PCB. We really won't know until we can see the innards of a 35S. Bill Wiese San Jose CA

Re: 41s Message #13 Posted by Paul Dale on 3 June 2007, 11:57 p.m., in response to message #12 by Bill Wiese Quote: There's really little need for the horsepower of an ARM. I'm sure the horsepower could be utilised in one form or another. I wouldn't go so far as CAS and possibly not even to full on matrix support. However, there is plenty of scope to make the mathematics more accurate and/or faster. E.g. using something like medium precision reals via the MPFR library. Knowing your answers are correct is comforting. Likewise being able to add new native functions (i.e. fast) via the inbuilt programming would be a major boon. - Pauli

Re: 41s Message #14 Posted by DaveJ on 2 June 2007, 3:55 a.m., in response to message #1 by Hugh Evans Quote: Alright, so the 35s isn't even out yet, but even so it's a good platform for making modifications partially due to its' thickness. Here is my proposal of what we should do with it to make it better: Gut the electronics, keep the LCD, make a new PCB with either an arm7 or arm9TDMI, give it about 512KB of SRAM, USB, SD/MMC card support, and load it with the command set of the 41c. We can give the keyboard a new set of labels with an overlay and silk-screen the keys. I would add IrDA to that. Dave.

Re: 41s Message #15 Posted by Hugh Evans on 2 June 2007, 4:47 a.m., in response to message #14 by DaveJ Of course, I neglected to mention that feature. It's almost implied around here!

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