#typedef Eric The_Annoying_GrandMa
you got new nick

(Calling main() from interrupt!?), don't you ever get bored?

In expecting from Dmitri wrote: .... and so on



Back to topic, i do agree that soft implementation is not a simple task, as maybe sounded from my post. Not a simple hardware task either.

1) Nobody is saying that single uC should handle 7 soft UARTS

2) You should consider finding your optimal solution using some modern 8051/52 components like:

http://para.maxim-ic.com/cache/en/.../4592.html

some quite speedy 2 UART built in devices. Only one way to determine how many soft UARTS you can implement is to spent some time coding and experimenting, not bugging it's impossible.
If you can achieve let's say 2 soft ones, then you'll need 2 uC for 8 UARTS.

3) Always try to find somebody elses solution if possible. I did not find any multiple UART projects (up to similar number of ports as you need) but i scoped some existing MIDI solutions (asychronous full duplex 31250 baud rate communication)

- on web page www.ucapps.de you'll find information about 4 channel MIDI router. He used dedicated PIC16F88 per each independent port as may not be an optimal one ( 1 uC per UART )

- i own Steinberg Midex, an 8 channel I/O MIDI Router. Fist glance on the PCB reveiled their realisation of multiple serial routing.

They use ST16C454 - quad universal UARTS, two of them for 8 independent ports, and Cypres CY62256 microcontroller. Guess this is close to optimal.

So it will be your decision where to start, but plenty of work you can expect for sure.

Best, Dmitri