In one of my projects, used a 89C51 WITH 89c1051 together for want of 2 Serial port at very low cost.

I have used one 8 bit port and 2 external ints of Both 89c51 and 89c1051 to exchange data. In addition 64kb NV memory also interfaced to 89c51.

So why not use the 89c1051 UART which is very cheap. Problem is the extra sw and chip programming.

Regards,

V.Nagarajan.