(circuit design) A digital logic circuit which can act either as a flIP-flop or as a serial shift register and which is used to form a scan path. The most common design is a multIPlexed flIP-flop: ___ ____ normal in --| | | | |------|D Q|---- normal/scan output scan in ----|___/ mux | | | | | test mode ----+ +----|> | flIP-flop | |____| clk ---------------+ The addition of a multIPlexor (mux) to each flIP-flop' s input allows operation in either normal or test mode. The output of each flIP-flop goes to the normal functional logic as well as to the scan input of the next multIPlexor in the scan path. The other common design is level-sensitive scan design (LSSD). (1995-02-14)