The answer regarding conversion to RS485 was the first idea I thought
     of. However, as long as you are doing a conversion, you could turn it
     into an IIC network over the same lines. This would work to the
     peripherals of the 16C63/73 at minimum by using the USART to interface
     to the lab device, and the SSP to interface to the controller. AND
     there are also IIC ISA boards for control on the PC side.

     A less expensive possibility is to use the 16C62/72 devices and
     implement the USART in firmware. Either way, the host should poll all
     of the devices on the network to determine if any has applicable data,
     in some sort of (nearly) round-robin scheme to keep the RAM buffers
     from overloading in the IIC slaves. And if you run the PICs >10MHz,
     you can run the IIC bus at 400kHz.

     More implementation notes: Remember to add a couple jumpers (three,
     say) to each interface module to help the conversion PICs determine
     which IIC address to use, and have the MSb(s) use an address that is
     not already co-op'd by Philips. Like 0101jjj, where 'jjj' represents
     the jumpers.

     Norm LeMieux
     MCHIP FAE/NW