Yet another ZX Spectrum clone on Sipeed Tang Nano 20k development board.

The firmware is still under heavy development. Border effects works incorrectly yet.

• HDMI output at 720x576 (49Hz)
• Analog sound output
• USB Keyboard
• Z80 Soft CPU (T80a)
• DivMMC with ESXDOS 0.8.9
• Turbosound (2x AY3-8010)
• Soundrive

1. Install openFpgaLoader tool
2. Upload bitstream into the external flash openFPGALoader -f impl/pnr/tang20k-speccy.fs
3. Connect USB keyboard (+5V, GND as well as D+, D- signals via 33 Ohm resistors)
4. Prepare the SD card (FAT32, ESXDOS 0.8.9)

• F10 - CPU reset
• F11 - NMI
• F12 - Reset

1. Refactor a videocontroller, implement it via a classic scheme with the scandoubler
2. Add i2c RTC and optionally i2c eeprom
3. Add ESP8266 module support via ZXUNO UART / AY UART or ZiFi UART standard
4. Add USB mouse as kempston mouse
5. Add USB gamepad as kempston joystick
6. Implement more video modes (like Timex hires, ULA+, etc)
7. Add Tape in/out
8. Create an addon PCB (motherboard?) for advanced peripherial