NerdWorld Report

Prototype Board

June 9, 2025

As I continued to design and build the JRC-65 computer, I knew I'd need a fairly large prototype board to test the system as I built it. I had already purchased some prototyping equipment, but the full 6502 system would require more real-estate than my old prototyping system could support. I also worried that my small wall-wart power supply would not be able to keep up with all the ICs and Arduinos and Raspberry Pis I'd need. I therefore decided to build a new, larger prototyping board.

The Details

I started with 7 breadboards that I purchased from Ben Eater. I'm sure there are dozens of these breadboards that can be found on the internet, but I felt reassured by Ben's endoresement of the quality of these particular boards. Also, I'm new to breadboarding, so I took his advice which mentions the importance of getting high-quality breadboards so you don't waste time chasing down poor connections from an inferior board.

I also needed a robust power supply. I had been using a simple 2 amp wall-wart, but worried it would not handle the complete 6502 system, the ton of LEDs it would have, and the multiple Arduinos I planned to use. Checking Mouser, I found this 5 amp 5-Volt power supply that seemed like it should be adequate. I wanted the prototyping board to be simple to use, so I made sure that 5 Volts was distributed to every breadboard section. I did this by running 12-gage stranded wire power bus on either side of the breadboards and tying them into the power bus strips on each breadboard. These were then secured with hot melt glue to hold them in place. I put a few LEDs on them to verify that power was being distributed.

Power Bus along the edge

Hot melt holds everything in place.

I plan to use several Arduinos in this project. One is used to control the master clock for the 6502. Luckily, it will fit into a DIP socket so there was no special provisions needed for it. However, I also needed an Arduino Mega 2560 to display the Hex address and data info on an LCD display. I therefore mounted the Mega 2560 on standoffs at one end of the board, and ran power to it by making a custom USB cable. A Raspberry Pi is also planned as the Human I/O and network interface, so a Pi had to be mounted and powered via its USB also.

All of these things were mounted to a stock 36"x10" white laminated shelf board I bought at my local hardware store. As a final touch, I zip-tied all the wires to make them tidy, and covered the bare power bus wires in wire conduit to shield them from short circuits. A 110 Volt light switch feeds the power supply.

Now I'm ready to begin construction!

The final assmebly with the power bus shielded