A method includes extracting a first netlist from a first layout of a semiconductor circuit and estimating layout-dependent effect data based on the first netlist. A data processing unit can extract the reception signal data from the first electrical signal and produce the second electrical signal in response to the transmission signal data. Each of the different voltage levels indicates a particular operational state combination of the plurality of memory chips. Accordingly, a user may purchase an item for a plurality of recipients quickly and efficiently. The legs assembly includes two terminal supports and center supports.