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  • Writer's picturerehsd

65816 Motherboard - Building Your Own

Updated: May 15, 2022

I have received several inquiries from others wondering about building their own version of my 65816 motherboard. If you're interested in building your own, read on...

Disclaimer #1: This is a hobby for me. I have no formal education or work experience in this field. What I am sharing below is what I have designed and am using as my 65816 motherboard. You are welcome to use the design files that I provide, modifying as you see fit. The design files come with no warranty. I suggest you validate all aspects of the design prior to purchasing your own PCBs, ordering parts, etc.

Disclaimer #2: I have high confidence that there are bugs, quirks, issues, and plenty of room for improvement in my 65816 motherboard design.

Disclaimer #3: A common question I get is about the ISA slot connectors. I am only using the physical aspects of ISA (i.e., the connectors and some of the same general pinouts). However, I am not following the ISA protocol spec, so other add-in cards outside of mine will not work in this system.

If you identify issues with the design or have suggestions for improvement, please drop me a note. I will do my best to incorporate improvements.

The current versions of my design files are available below, including Gerber files. The design files were built in EasyEDA (V6.5.1 most recently). Realistically, you are going to want to have the project open in EasyEDA as you build the PCB, allowing you to verify connections, components, etc. The silkscreen on the PCB will provide some guidance, but is not comprehensive.

Schematic_65816 Motherboard 1.0_2022-05-04
Download PDF • 1.11MB
Gerber_PCB_65816 Motherboard 1.0
Download ZIP • 2.79MB
Download ZIP • 1.90MB

Bill of Materials

To build out the motherboard in its entirety, you will need the following items (minimum). Many of these parts have alternates. I am listing the parts that I am currently using. Any prices listed are estimates as of May, 2022, in US dollars, and do not take into account shipping, handling, taxes, tariffs, duties, or other fees. While prices are not all listed below, I expect that a set of five motherboard PCBs and parts to populate a single board will cost $200 or more (plus S/H, taxes, etc.). You may do better (or worse) for costs, depending on where you source your parts. You will also need a soldering iron, EEPROM+PLD programmer, and other tools.

  1. Motherboard PCB (four-layer). A set of five from JLCPCB currently costs approximately $87 ($17.50 per board).

  2. W65C816S6TPG-14, qty. 1, $13.

  3. 74AC245PC, qty. 1.

  4. CD74AC573E, qty. 1.

  5. W65C22S6TPC-14, qty. 1, $10.

  6. SST339F040-70-4C-PHE, qty. 1.

  7. 32-pin ZIF for SST339 ROM, qty. 1.

  8. IDT71256-SA15TPG, qty. 1.

  9. ASC6C4008-55PIN, qty. 1.

  10. SN74F260N, qty. 1.

  11. SN74AC14N, qty. 1.

  12. CD74AC00E, qty. 1.

  13. GAL22V10D-10LP, qty. 1. (This will need to be programmed for address decode logic. For details on my decode logic and the programming for the PLD, see this folder.)

  14. SN74HC14, qty. 1.

  15. SN74HC595, qty. 2.

  16. 555, qty. 4.

  17. SN74HC08, qty. 1.

  18. SN74HC32, qty. 1.

  19. SN74HC00, qty. 1.

  20. SN74AHC74, qty. 1.

  21. SN74AHC04, qty. 1.

  22. CD4068, qty. 1.

  23. Trimpot, 220K, qty. 1.

  24. Trimpot, 1M, qty. 1.

  25. Oscillator (1 MHz to 28 MHz), qty. 1. (The oscillator is halved before going to the processor. 14 MHz to the processor runs well for me. Something slower may be good to have on hand in case you encounter issues at 14 MHz.)

  26. Switch for clock auto/manual, qty. 1.

  27. Momentary switch, qty. 2.

  28. Barrel power connector, qty. 2.

  29. Screw terminal, qty. 8.

  30. PS/2 connector, qty. 1.

  31. Sockets for ICs, if desired. (recommended)

  32. Pin headers, male or female. (based on preference)

  33. Jumper pins and shunts, qty. 30.

  34. Capacitor 0.01 uF, qty. 35. (general filtering cap, can size according to preferences)

  35. Capacitor 0.1 uF, qty. 40. (general filtering cap, can size according to preferences)

  36. Capacitor 10 uF, qty. 15. (general filtering cap, can size according to preferences)

  37. Capacitor 100 uF, qty. 10. (general filtering cap, can size according to preferences)

  38. Capacitor 470 uF, qty. 10. (general filtering cap, can size according to preferences)

  39. LEDs, qty. 3.

  40. ISA slot connector 98-pin, qty. 7, $1 each. ($0.69 each with $30 minimum order here)

  41. Bus resistor array, 9-pin, 1K, qty. 10.

  42. Resistor, 3.3K, qty. 20.

  43. Resistor, 1K, qty. 10.

  44. Resistor, 1M, qty. 2.

  45. Resistor, 330K, qty. 1.

  46. Resistor, 33K, qty. 1.

  47. Resistor, 330, qty. 3. (for LEDs, can size to preference for selected LEDs)

  48. Anything else I missed from the PCB...

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