As-easy-as-possible, but still expandable single board computer with 65C02 CPU.
Issue 4 is available
Issue 3 adds a 6522 VIA circuit. It features:
- A pair of 8bit parallel ports.
- Each pin of each port can be individually set to the input or to the output.
- Serializer (8 bit shift register)
- A pair of 16bit timer / counter
Issue 4 fixes some problems in the Issue 3 design. See below.
Issue 3 problem fix
Issue 3 board has some design problems, which is fixed in the Issue 4. Issue 3 is fully working, but you have to manual solder:
- A wire between GND port and a pin 8 of the 74HC138.
- A 180k resistor parallel to the Q1 (between the CPU pins 3 and 37).
- A 47pF capacitor between the CPU pins 1 and 3