I have a need for an RS-485 Network.

The network will have one master , a pc with an RS-232 -> RS485 converter.
Most of the slaves will be minor function nodes ( one or 2 I/O lines ) and a
few will need to be a lot bigger.

I've taken a look at the spec sheets for various PIC's ( those with buit-in
USARTS and others ) and i've also gone through just about every one of
MAXIM's RS-485 chips.

I'd like to be able to use something as small as a 12c509 for the smaller
slaves (Cost is a major factor here), im also prepared to go for the bigger
PIC16C63/6 types for the larger nodes.

Doing this im going to end up lots of different mixes of hardware and just
about every chip is going to need special tweaking.

What ideas do you have for trying to keep the network as uniform as possible
whilst also keeping the node cost down to a minimum?

Should i look at other RS-485 drivers than the maxim ones?  I know theyre
pricey, but where i am u gotta work with what i can source locally.

John