Make an expansion board with a serial port(s) for WL-500b/g

[Technik]

Yes you can use an old chips if they can operate at 13 MHz clock rate. That's why I put the UART to socket - sometimes it's not easy to find a datasheet of some specific chip... 16c55x recommended because of FIFO buffer.
It should be also possible to use XTAL with lower frequency and change the serial port initialization to get the same baud rate.

BTW this is a list of PMON commands:

...
Opened ethernet
Downloading from ethernet, ^C to abort
break!
~PMON> h
      h  The help command                           m  modify memory
   copy  copy memory                                d  display memory
   fill  fill memory                           search  search memory
compare  compare memory                         uncmp  Uncompress gzip file
    set  display/set variable                   unset  remove variable
     hi  display command history                 vers  display version info
   load  load memory from hostport               call  call function
  cp2fl  Copy Ram to Flash                     nvInit  no options
nvErase  no options                            etdiag  enet diag. test
 ildiag  iline diag. test                      rmdiag  sdram diag. test
 mpdiag  mass production diag. test           pcidiag  pci interface diag. test
pmadiag  pcmcia interface diag. test          leddiag  led gpio interface diag. test
usbdiag  usb interface diag. test             plpdiag  parallel port interface diag. test
PMON>

The help function is working also for every listed command.