Using the TinyDuino, TinyDisplay and USB card I created a very simple Serial sketch and the serial device does not become ready so if I print something it is garbage. Garbage is output at the 4 second rate in the attached sketch. Input on the Mac serial device is attached in the screen shot. I use the same serial device and cable to program the TinyDuino which works fine.

So, it turns out that when I set the serial baud rate thusly:

Serial.begin(9600);

I have to create a serial port with a baud rate of 4800 and unset "Set DTR and RST".

Works fine now.

BTW this is with the "http://www.baeyens.it/eclipse/V3/" Eclipse plugin and behaves the same in OS X El Capitan and Windows 10.

http://forum.tinycircuits.com/index.php?topic=1901.msg3730#msg3730