Please read this page from the main YASEP interface
Execution units 16-bits mode, switch to 32-bits mode 32-bits mode, switch to 16-bits mode ptr=
(LSB of Ax reg)
SND=
(reg)
SI4=
(r/Im4/Im16)

This window lets you define input data and see the results given by the different execution units, for all the valid opcodes. Use this tool if you are unsure about the result of an instruction.