Q: How to load rom for test ?
A: edn8usb testrom.nes

Q: How to load rom with custom fpga mapper for test ?
A: edn8usb edfc-fpga.rbf testrom.nes

Q: Where i can get drivers for usb port?
A: http://www.ftdichip.com/FTDrivers.htm

Q: Can i use USB port to transfer some debug data from nes to PC?
A: Yes
1) lda #1, sta $4400, lda #3, sta $4402 //magic initialization
2) now we can communicate with PC via $4401
also can be usefull to check $4403.1 and $4403.2 before than read or write to $4401. 
$4403.1 shows if port ready for read
$4403.2 shows if port ready for write
fpga bus_mode should be equal to 3(BMOD_REGS), otherwise access to custom registers will be closed
From PC side communication interface looks like standard serial COM port 

Contact me if you have some other questions about this stuff
biokrik@gmail.com
http://krikzz.com/forum/

07.02.2013
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