I have been looking at this Mega103/128 board , it seems like one that is possible to do at home (Single sided , eagle layout)
But i do not understand the 4053 analog switch he is using , to pin2/pin3 from the Mega , between a max202 and the ISP plug :?: :?:
Arent MISO/MOSI used on a Mega103/128 , to do ISP programming ???
Can anyone help out here ???
Documentation in german (Schematic at last page)
The Eagle Project