Data : This instruction extracts one byte (8 bits) from a given register, emulating the "Load Byte" instruction of Load-Store architectures. The data is shifted right, according to an offset, and the MSB are filled with the sign bit of the extracted data.
Address : If the source register is a static register, then the offset is zero. If the source is a Data register, the 2 LSBs (or only one for YASEP16) of the corresponding Address register are used as offset, and this Address register is updated with this offset.
Note : this instruction was meant to use auxiliary data from other registers. As of 2009-07, in order to use the auto-update function, the extended form (32-bit instruction) must be used.