Improved apparatus and process for testing a variety of electronic components, such as printed circuit boards (101, figure 3), which have a large number of potential circuit paths. The apparatus of the invention is characterized by a versatile searching sequence which achieves a surprising combination of search speed and efficiency and hardware economy. Advantages embodiments of the invention enable multiple test stations (32, 34, 36, figure 1) to be connected in parallel to one set of switch cards through special "matrix boards" (90, figure 3). Multiplexing of the switch cards is accomplished by only bringing one circuit board into contact with test probes at one time. The sytem has a microprogrammed sequencer wherein signals representative of pin and board designations of switch boards are utilized in conjuction with a PROM which normally contains the next address to the currently-addressed pin and board designation.