Hmm - waiting for my next trip over to SFO to get hold of a HP35s - it would be a sin to break apart an HP41c - but the 35s hmm. It seems to have lots of room inside it. Isn't this the chance we've been waiting for to open it up and create a frankenstein monster based on Eric Smiths execellent previous work? Adding a mini usb and sd card should be simple - the CPU, well there are plenty of us around to get an open source version running ?