Hello!

I'm kind of new in the 8051 world. I've previously been working with other micro-controllers(PICs, Motorola etc..:-) but not the 8051.
What I'm looking for is an 8051 with 2 UARTs, CAN-controller execution in external memory. Both of the UARTs should communicate through 9-bit RS485 with address bit and full duplex. One of them with a low data rate but the other one with 256kbaud data rate. The question is how do I know if a certain MCU is capable of handling 256kbaud data rates. I suppose the UARTs data rate is derived from the oscillator frequency in some way. Is this done the same way in all 8051 MCU:s, or does this differ between differnet 8051:s? Does anyone know of any 8051 with built in hardware receive buffers? The UARTs that I've come across previously has been with 2-3 levels of receive buffers but i would assume that a deeper buffer could be necessary to avoid over-run... The 8051 also has to have a bunch of I/O:s and a couple of timers but as far as I've seen this shouldn’t be a problem.
The Dallas DS80C390 seems to fulfill but how cost effective will it be? Does anyone know the approx. price in 1k volumes? I've also been looking at some Philips and Infineon parts but have not come across any MCU:s with 2UARTS and CAN. Maybe a more cost-effective solution would be to have an external UART or an external CAN-controller to the Infineon or the Philips part...

All suggestions and comments are very appreciated.