37.9.2.2 Byte Select Access
Byte Select Access is used to connect one 16-bit device. In this mode, read/write operations can be enabled/disabled at Byte level. One Byte-select line per byte of the data bus is provided. One NRD and one NWE signal control read and write.
For 16-bit devices, the SMC provides NBS0 and NBS1 selection signals for respectively Byte0 (lower byte) and Byte1 (upper byte) of a 16-bit bus.