PDA / HP-41 Hybrid Hardware? (Just wondering . . . )


For $5.00 on clearance at Office Depot, I just found a Fellowes "Type N Go" PDA keyboard for a Palm V / Vx. I checked and they're selling for similar amounts on eBay.

It's a goofy little plastic clamshell case with a spot for the Palm to slide into, and an ugly numeric/alpha/functions keyboard inside the front cover. Obviously, deep inside (I haven't got it fully disassembled yet) it's got the circuitry necessary to graft a keyboard onto a Palm PDA. (Some driver software is included as well.)

I don't even have a Palm (yet), but it got me to thinking of a way to "reincarnate" a broken-down HP-41C. If the circuitry inside this thing could be made to graft an HP-41C keyboard onto a Palm PDA, and if the Palm's guts could be made to slide in & out of the top of the 41's case, then one might be able to create (with software) a combination calculator/PDA with a nice keyboard.

In "retracted mode", maybe only the top half-inch of the Palm's screen would show, where the 41's display used to be. In "extended mode", full-screen PDA functionality would be available.

I believe the 41's keyboard PCB could be connected to the Type N Go circuitry. Whether the keypresses result in similar electrical connections may indeed be an issue. (For example, I noted when fooling around with Pioneer keyboards that a certain amount of electrical resistance is expected by the chip -- simply shorting traces together didn't work.) But this can be tested with a multimeter -- I'll check that tonight. Obviously, the actual key-for-key correspondence wouldn't necessarily be that important, as they could be re-mapped by software.)

I have noted that a PDA's innnards might indeed be shoehorned into a 41's case, with some creative reconstruction. I don't know about the exact dimensions of a Palm V, nor whether it could be adapted to such a role (with or without its original external case).

But, if this could be pulled off, the PDA would bring with it lots of plusses: memory, connectivity, development tools, touch-screen capability, etc., while the 41's keyboard and case would no doubt continue to provide its great look & feel for years to come.

This isn't the first brainstorm along these lines with which I've been afflicted. I recently traded for an empty Card Reader shell to experiment with grafting the electronics from my TI-83+SE into the HP-41. The TI brings with it many of the benefits of the PDA: FLASH-upgradeable OS, lots of RAM, PC connectivity, and (for development) a Windows emulator & Z-80 Assembler development tools.

What's especially attractive about the TI-83+SE is the separate LCD PCB, connected to the relatively short main board via a 15-conductor (IIRC) ribbon cable. That would enable an extendable/retractable display like I envision for "the ultimate modern calculator".

Unfortunately, the LCD (and its board) is just a wee bit too wide to fit comfortably within the 41's case, and so would dictate rather more substantial rework than would be desirable. (However, I'm not sure I'd even need the card reader shell to extend the case lengthwise.)

Anyway, if you're still with me, any comments?

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