[rescue] pocket terminal project, chip suggestions please?

[Tim H.]

I am hoping to make my Handera more useful as a terminal by adding a
portable keyboard, unfortunately the PDA can only talk to one serial
device at a time.  

I have a Landware GoType keyboard which has an external serial port,
however it will act either as a keyboard or a PDA cradle, not both
simultaneously.  

What I would like to do is create a device, with three serial ports,
which would act as a blind terminal, while echoing both what I typed and
what came back to the terminal program on the Handera, and passing
output from the Handera through to the remote device, to allow use of
macros and support for keys the keyboard lacks.

It would also need to function as a "normal" palm keyboard for input to
the Handera.

Requirments are:
Operation from the power out of the palm. If this is unreasonable there
is room in the keyboard for a AAA battery pack.

Small size, it needs to fit into the GoType keyboard

Optionally, it could be done with two serial ports if the device has the
brains to act as a keyoard decoder to replace the decoder currently in
the GoType, which would probably help with power consumption.

It also needs to be inexpensive to buy, and programmable without an
expensive interface.

If I manage to make this work, it will work with any PalmOS device,
which means even an original Palm Pilot would work as a terminal,
without having to fight with graffiti.  It would also be transparent to
the palm, and should work with any terminal package.

My last microcontroller programming was a decade ago, on 8051
controllers, and I am completely unaware of what has become available
since, so pointers to controller lines that would be appropriate would
be great.