Facilitate learning the Z80 Retro! hardware and software.

ESP32-s3 based board to provide WiFi enabled features.

• RS232 connection to main Z80-Retro console via cable for telnet console access
• RS232 connection to Z80-Retro Aux com port via cable for future WiFi enabled serial download.
• Z80 bus programmer using MCP23S17 SPI IO expander devices.
  • facilitates faster Z80 bus access at 10Mhz SPI rate.
    • Serial access still relatively slow but 25x I2C.
  • Program Flash without the need for a Raspberry Pi.
  • Might be possible to program areas of SRAM memory e.g. future WiFi file download.
• Off-board SPI using header connection to future board(s) such as FPGA video card.
  • programming FPGA plus additional SPI-FPGA debug features if needed.
• One byte, 8 bit, message register implemented in logic for handshaking with Z80.
  • uses IORQ addreess line 0xA4.
• USB OTG is present in hardware.
• SD card slot for future possiblities.