3=3 wire SPI
4=4 wire SPI
2=I2C
6=6800 8 bit parallel
8=8080 8 bit parallel

s=Arduino Standard Software Communication
  pinMode and digitalWrite are used for communication
o=Arduino Optimized Software Communication
  uC Specific low level functions for digital write and read
h=Hardware Communication with Standard Libs
  TWI and SPI library
H=uC specific hardware communication


SSD1306 128x64 
  Arduino with ATMega328 (e.g. Uno)	s2s3s4s6s8 h2h4
  Arduino with AT91SAM3X8E (Due)		s2s3s4s6s8 h2h4