|Re: despite the likelihood of more squishy keys|
Message #4 Posted by Paul Brogger on 18 June 2002, 3:37 p.m.,
in response to message #2 by Tom (UK)
I doubt very much that a 20s can be hacked at all. I haven't taken one apart, but all of the other "later" Pioneer models are single-chip designs, with single-sided exposed copper (not multi-level gold-plated) circuit boards. (The 32SII PCB is a one-component design: the surface-mount chip, with connections to the keyboard, display and battery.)
Just because we can upgrade the RAM on the 42s, don't get your hopes up for any similar 20s modifications. In fact, the 42s has two sets of surface-mount pads etched onto the PCB: the RAM set and one for an alternate ROM. The lower-end and later models have no such avenues of extensibility built in. (Unless I'm missing something REALLY subtle!) Even the 32sII's precursor, the old 32s, which shares the 42s' technology (gold-plated PCB and chip "riding in a hammock" of micro-fine connections) has no external memory pads or other obvious means of expansion.
I bought a TI-83+ Silver recently, but haven't started messing with it yet. (Now that I've bought it, I'm not sure I'll ever have time . . . ) It's a Z-80 based unit in a pretty solid package, with a graphic matrix screen and something like 1.5 Mb of Flash ROM. A Zilog assembler and SDK, a Windows emulator, and (literally) hundreds of pages of TI documentation are available for free. It ought to be available for a while, and it may indeed be amenable to fundamental redesign. (Though there are now only two limited modes offered for software enhancement, and documentation of the calculator OS "kernal" is apparently still proprietary.)
Also available is the TI-89, which is 68000-based, with similar support tools and documentation available. (And both have available PC connectivity, too.)
I think it would be fun to get an interested group cooperating on a next-generation RPN device by all agreeing to work through some available, promising technology with adequate developer support . . .