> 	Has anyone managed to get the mac HP48 (calculator) cable 
> connection to work?  I was going to play with it, but the instant I plug 
> the cable in, *everything* freezes (console, X, whatever I'm in), then 
> when I unplug, I get a "ring overrun" message.. I remember the 
> instafreeze trick happening on the mac side if I left it plugged in while 
> booting..  (on a different mac)

Sorry it has taken so long to get back.

I think your problem is that the HP calculator is doing something strange
with the signals. Most likely, it's providing a clock signal on one of
the handshaking pins.

The easiest thing to do, if possable, is to hook an oscilliscope up to
the pins and see what's going on.

Once you've done that (or as an experiment) you can tell the kernel
(if it's the 1.2 pre-release) about the clock signal using booter 1.9.3.
When you set a clock up (in the serial port settings menu), this interrupt
gets turned off. The problem is that the kernel normally
expects these pins to be DCD and CTS, and changes in these signals sould
be passed on to the rest of the kernel. A many-kHz clock was not in the
scheme of things. By telling the system about the clock, the interrupt
gets turned off.

Take care,

Bill