Signalling voltage question

[JBotAlan]

Hey all,

I have somewhat of an interesting question/problem. I am trying to interface a Handspring Visor (a very old PalmOS device) to the dashboard port on the OI. Now, the way I understand it, the OI's port is a standard RS-232 port. That would imply it is signalling at, like, +/- 12 volts, wouldn't it? The port on the Visor demands 3.3v, and I think that's a maximum, not a minimum. Is there an easy way, other than trying to track down a serial dock, to do the hardware interface here? I know which pins are the serial pins on this device, but I don't want to fry it with 12 volts. EDIT: Forgot to mention, I am definitely cracking the device open, so the physical interface is not a problem.

I am developing software for it, and this will be open-source for future teams if I get anywhere with it. It's the perfect dashboard device--small, lightweight, battery lasts *forever* and has audible and visual feedback. And an open SDK to boot.

I just don't know enough about the electrical side. I understand there's a way to drop voltage with diodes/a resistor but I don't understand it fully. Perhaps an experienced EE can help me...

Thanks in advance,
JBot

EDIT2: Ohh! I could just use a MAX232 couldn't I?