"For ten UARTs it requires about 800 cells"

From the Keil Forum:

"The E520 has 2048 CSL 'Cells', and a full UART can be imlpemented in anything from 152 to 360 Cells (depending on whether you also want FIFOs, modem-control, etc, etc)

"So that's a max limit of 5-13 full UARTs - but then you wouldn't be able to add any other 'soft' peripherals!

"And programmable logic means you can do things like only have 'half' a UART if you only need to receive or transmit, but not both..."

http://www.keil.com/discuss/docs/thread1868.htm

See also: http://www.8052.com/forum/read.phtml?id=56975