Parallax 28803 Board of Education Full Kit USB version Mechanically interlocked power supply to prevent dual connection of wall-pack and 9-volt battery USB connection for programming and communication during run-time Female 10-pin dual row connector for optional AppMods (more breadboard space) Traces on top of the board show connections between BS2-IC and breadboard connections Vdd and Vss connections brought adjacent to 5.1 x 3.5 cm (2" x 1 3/8") breadboard area