Hi friends,
I need help in selecting the components and in assembling them (additional circuitry required, if any) for a system Im trying to develop.

The specs are as follows:

8051 compatible controller (@12MHz),
2-4kb flash ROM
32 DIO channels
2 A/D Channels (Differential Inputs @±15vDC and 8-bit resolution)
3 D/A Channels (Differential Inputs @±15vDC and 8-bit resolution)
4 Nos. RS-485 ports.
for one system and 72 instead of 32 DIO ports and 5 RS-485 ports instead of 4 for another system.

I guess Cygnal has the chips that come with Built-in ADC and DAC but are limited to around ±5v. Is there any way out...
Then which chips support RS-485 (4-5 ports)?

Also I need help (atleast links) on how to connect them to the 8x51. I believe you should have some Capacitors and Resistors in between...

Please help me ASAP.

Warm Regards,
Sriharsha