E&L instruments cmos/ttl designer. Excellent breadboard with clock, voltage source, monitors, logic switches, and other circuit design tools built into permanent housing. Used to significantly reduce design time of prototype circuits and quickly troubleshoot errors I have 4 CD-1 and 3 DD-1 boards CD-1 boards are $50 each and are fully functional Fully functional DD-1 boards are $25 each DD-1 boards in need of repair are $25 each Discount for orders of 2 or more Please note that not all DD-1 boards are fully functional. Inside, there have been a few wires cut, but the colors on wires of both ends of the cut will make the repair work easier. Because the wiring is not complete, full verification of functionality cannot be performed, but initial inspection suggests there to be no problems. All ICs inside are in sockets which would make repairs incredibly quick if needed As I have time I will be repairing them and replacing the wires on both CD and DD models with PTFE wires and I will update prices and availability as I do.