PSGOUT: Send PC audio to MSX PSG over JOYSTICK2 included in MSXDISK 0.99.1

By ocitygate

Expert (70)

ocitygate's picture

28-11-2021, 17:55

Download MSXDISK.ZIP

System Requirements
1. Real MSX computer with 64K of RAM and Z80 CPU at 3.58MHz
2. Connection cable between audio output (PC) and cassette recorder port (MSX).
3. Connection cable between USB (PC) and JOYSTICK2 (MSX)
USB to TTL RS232 Adapter

JOYSTICK2 PIN1 to TTL TX (green)
JOYSTICK2 PIN6 to TTL RX (white)
JOYSTICK2 PIN9 to TTL GND (black)

Instructions for PSGOUT
1. Open MSXDISK.EXE and choose RS232 port.
2. Power up MSX and type BLOAD"CAS:",R then click Play Casette, PSGOUT and click Play button.
When complete "Listening for audio..." should appear on MSX. Click Close button.
3. Click PSGOUT.
4. PC audio should be sent to MSX PSG.

More Info
PC Audio is transmitted to MSX at 57600bps ie. 5760 bytes per second including a start bit and stop bit per byte.
Now, every byte encodes a transition in the form of channel (0-2: 2 bits) and volume (0-15: 4 bits) and 2 padding bits during which the PSG register is updated.

References
Playing samples on the PSG Grauw
Crystal clean PCM 8bit samples on the poor PSG ARTRAG

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By Grauw

Ascended (10317)

Grauw's picture

17-12-2021, 22:47

I saw the Youtube video on Twitter. Very cool!

By ocitygate

Expert (70)

ocitygate's picture

04-01-2022, 21:10

Thanks Grauw. Means a lot coming from you.