More about math, calculators, RPN and programming

[robert rozee]

take a deep breath everyone, and think of your happy places!

i've actually been following the 43S thread with interest, and the lamenting of the lack of progress. here seems as good a place as any to put forward a few ideas.

we've seen a credit-card sized HP-25 emulator built using quite minimal hardware, and swiss micros are shipping their tiny HP-41 reinterpretation. the level of interest in both on the forums suggests to me that perhaps the time is ripe to look at someone doing a run of 'homebrew' HP-42S calculators.

the same keyboard solution as used on Chris Chung's "HP-25C Eumulator". a standard 1602 LCD module for the display (16x2 characters, HD44780 based). 2xAA cells for power directly to processor and LCD module. a PIC32MX170F256B (28-pin DIP package) to run it all, with 256k flash and 64k RAM on board. and running Free-42 as the calculator firmware.

i reckon that minimal additional components would be required beyond PIC32, display module, and keyboard switches. the processor has it's own on-board clock generation and around 20 spare I/O pins to connect to everything. the keyboard could be charlieplexed if needsbe to save pins.

comments?

cheers,
rob :-)