Hardware schematic for Fastbeta ZX Spectrum. You can combine both VGA and HDMI video outputs or solder only one of them

Composite Video output on GP13. Make sure both TV and computer hardware GND are connected

Optional PSRAM connection (RP2040 only, not applicable to RP2350):

PSRAM_PIN_CS=GP18
PSRAM_PIN_SCK=GP19
PSRAM_PIN_MOSI=GP20
PSRAM_PIN_MISO=GP21

supported PSRAM ICs:
Espressif ESP-PSRAM64H
apmemory APS6404L
Lyontek LY68L6400
IPUS IPS6404

Full list of RP2040/RP2350 pins used by Fastbeta:

GP0 - PS/2 keyboard clock
GP1 - PS/2 keyboard data
GP2 - SD card clock
GP3 - SD card MOSI
GP4 - SD card MISO
GP5 - SD card CS
GP6 - VGA BL / HDMI_CL-
GP7 - VGA BH / HDMI_CL+
GP8 - VGA GL / HDMI_D0-
GP9 - VGA GH / HDMI_D0+
GP10 - VGA RL / HDMI_D1-
GP11 - VGA RH / HDMI_D1+
GP12 - VGA HS / HDMI_D2-
GP13 - VGA VS / HDMI_D2+ / Composite video
GP14 - NES controller clock
GP15 - NES controller latch
GP16 - NES controller data
GP18 - PSRAM_PIN_CS
GP19 - PSRAM_PIN_SCK
GP20 - PSRAM_PIN_MOSI
GP21 - PSRAM_PIN_MISO / Clock for external AY8910
GP22 - Real audio input
GP26 - PWM sound AY R / I2S DAC DATA
GP27 - PWM sound AY L / I2S DAC LRCK
GP28 - PWM sound Beeper / I2S DAC BCK
GP29 - Clock for external AY8910

Fastbeta keys

To flash the firmware press and hold BOOT SEL button on your RP2040/RP2350, connect USB cable to the computer, copy the firmware UF2 file to the external flash RP2 drive

New firmware FASTBETA37a. Both RP2040 and RP2350 support, volume control for I2S DAC sound output, file browser speedup, keyboard joystick changes, minor code optimizations, bugfixes

ps. scl and hardware AY fixes added

New firmware FASTBETA38. Composite video support, combined VGA/HDMI/Composite driver, auto-detection of any video mode, improved AY8912 sound emulation, added 6-channel stereo Philips SAA1099 PSG emulation, code optimization, bugfixes

New firmware FASTBETA38a. Bugfixed and improved SAA1099 emulation: frequencies, envelopes, and operating logic

New firmware FASTBETA39. ROM flashing procedure from SD, 15-20% overall performance boost, composite video mode improved, some Z80 emulation issues fixed, DivIDE jumper added

New firmware FASTBETA39c. Bugfixed version with improved performance, pentagon model ROM (64k, four 16k banks) can be flashed correctly, added reset to system ROM