HBC-56 Schematics / PCBs THis directory contains all of the schematics and (some) PCBs/Gerbers for this build. Schematics with PCBs HBC-56 Backplane HBC-56 Proto Card Schematics only 6502 CPU Card 3-way Clock Card RAM/ROM Card Character/graphics LCD Card TMS9918A Display Card Dual AY-3-8910 Sound Card Keyboard / Dual NES Card