Hello,
I have a arduino 2009, a standard Ethenet shield and a standard mini-breadboard shield.
When I look at the Ethernet shield Eagle printed board schematic I see that most I/Os are linked to the shield. Only analog in A2 to A5 and digital I/O 7 are not connected, and digital I/O 0-1 are devoted to serial link.
Then my question is : may I stack the board and the shields and use without special care all the analog and digital I/Os on the breadboard ?
Many thanks
Alain
No, you can't use all of the pins with your breadboard circuit: the 4 used for the SPI interface to the Wiznet chip (D10-D13) are unavailable.
Also, the "standard" Ethernet shield has some circuitry for the SD card interface that includes pull-ups on A0 and A1 that will cause problems if you try to use them as analog inputs (but probably won't interfere with using them as digital I/Os). The Adafruit Ethernet shields that I use don't have those, so only D10-D13 are "off-limits" for normal use.
Ran
Thank you Ran,
I missed the SD card (X1 on Eagle schematic) which is not implemented, now I understand the schematic.
Many thanks for your help! 
Alain