W25Qxx
The W25Qxx is a common series of serial EEPROM chips.
Naming
These EEPROM chips are typically named "x25qxxx" where the first x indicates the manufacturer ("W" indicates Winbond) and the xxx after the Q indicates the size (in Mbits). A "W25Q128" is therefore 128 Mbits = 16 mB EEPROM manufactured by Winbond.
Connections
W25Qxx devices are available in a number of different packages, but the most common is a SOIC-8 package. These will typically have the following pinout:
It is worth noticing that many (if not all) of these devices can operate in two different "modes". Regular SPI with a MOSI/MISO pair of signals, and Quad-SPI where 4 data lines are being used.
Memory Layout
To be added