Ugh. So I finally got SoftMPU to play nice with my build and guess what? Pi 4 wants nothing to do with the adapter, main PC is able to receive the MIDI signaling.

Why the hell is my Pi 4B unable to communicate through serial? I am using the exact same cable, and null modem gender changer, that James Mckenzie over on YouTube used with his setup!

Why did it work for him but not for me?!

If you want help, you should list specifics rather than just complaining "thing doesn't work".

Did you read the documentation and configure the USB serial option in the MT32 Pi config? The Pi doesn't do anything with serial input if you don't.
https://github.com/dwhinham/mt32-pi/wiki/MIDI … r-USB-to-serial

Using serial for MIDI can be complex. Does your retro PC not have a soundcard with onboard MPU? USB Midi adapters are inexpensive and plug and play on the Pi.

Okay well for starters, yes I did configure USB serial in the MT32 Pi config unless I need to tell it not to receive serial data over the GPIO?

GPIO thru is disabled, USB is enabled unless that's for USB MIDI? USB Serial is set to 38400 bauds, so is my socket 775 PC. I know this all works because I can playback MIDI using my main PC over the adapter at 38400 bauds.
The Audigy has a gameport but I don't know if the Audigy has MPU on board, also I do not have a cable to convert the gameport to MIDI either.

Documentation says that it should detect my USB to serial adapter, which has a PL2303 serial converter chip. Like I said, I know the cable works because I can transmit over to my main PC over USB.

Hold up, the Sound Blaster Audigy is really an XP era card. Are you running the game in pure DOS mode or via DOSBox in Windows?

A socket 775 machine should have zero issue running DOSBox as well as a copy of MUNT at the same time. This would give you MT32 sound and you wouldn't even need the external device. Alternatively you could use a USB -> MIDI interface out from the PC and then a 2nd to bring the signals into your MT32 Pi.

I got inspired by Phil's Socket 775 Win 98 build and the Audigy is nothing but troubles so far for me, I'm replacing it soon with a CMI8738 based soundcard.
I'm also getting a Startech RS232 to USB cable, the FTDI based one that's already wired up for null modem and has the indicator lights on it. The Sabrant one uses the PL2303GS chipset which might be iffy with MT32-Pi

Since its Win98 through and through I'm running everything in pure DOS, but also in Windows if the game I play has General MIDI support.

Also tried my sister's Casio keyboard with the Pi and the USB ports are totally fine, I can use the Pi as a synth with her keyboard.

emmanu888 wrote on 2026-02-18, 23:54:

I got inspired by Phil's Socket 775 Win 98 build and the Audigy is nothing but troubles so far for me, I'm replacing it soon wit […]
Show full quote

I got inspired by Phil's Socket 775 Win 98 build and the Audigy is nothing but troubles so far for me, I'm replacing it soon with a CMI8738 based soundcard.
I'm also getting a Startech RS232 to USB cable, the FTDI based one that's already wired up for null modem and has the indicator lights on it. The Sabrant one uses the PL2303GS chipset which might be iffy with MT32-Pi

Since its Win98 through and through I'm running everything in pure DOS, but also in Windows if the game I play has General MIDI support.

Also tried my sister's Casio keyboard with the Pi and the USB ports are totally fine, I can use the Pi as a synth with her keyboard.

The main issue is Socket 775 can be used for Win 9X. But the MT32 era of gaming was in very early DOS. Those games really want ISA sound cards, and PCI pure DOS mode support was spotty even on Socket 754 423, and 478.

If you use a USB MIDI adapter from with Windows, it will show up as a MIDI in and out device. If you then run games through DOSBox you can select the MIDI output device which is the USB MIDI adapter. From there use a MIDI coupler to another USB MIDI adapter that's connected to your MT-32 PI. Using DOSBox will let you let you adjust speed as many earlier games have speed issues, and you are on a very fast computer. DOSBox can also be configured to have it's virtualized MPU401 be in intelligent mode so you don't need to mess with SoftMPU. Yes, it's not pure DOS mode, but you are trying to run really early DOS games on hardware that might have been released after Vista came out.

SScorpio wrote on 2026-02-19, 00:20:

emmanu888 wrote on 2026-02-18, 23:54:

I got inspired by Phil's Socket 775 Win 98 build and the Audigy is nothing but troubles so far for me, I'm replacing it soon wit […]
Show full quote

I got inspired by Phil's Socket 775 Win 98 build and the Audigy is nothing but troubles so far for me, I'm replacing it soon with a CMI8738 based soundcard.
I'm also getting a Startech RS232 to USB cable, the FTDI based one that's already wired up for null modem and has the indicator lights on it. The Sabrant one uses the PL2303GS chipset which might be iffy with MT32-Pi

Since its Win98 through and through I'm running everything in pure DOS, but also in Windows if the game I play has General MIDI support.

Also tried my sister's Casio keyboard with the Pi and the USB ports are totally fine, I can use the Pi as a synth with her keyboard.

The main issue is Socket 775 can be used for Win 9X. But the MT32 era of gaming was in very early DOS. Those games really want ISA sound cards, and PCI pure DOS mode support was spotty even on Socket 754 423, and 478.

If you use a USB MIDI adapter from with Windows, it will show up as a MIDI in and out device. If you then run games through DOSBox you can select the MIDI output device which is the USB MIDI adapter. From there use a MIDI coupler to another USB MIDI adapter that's connected to your MT-32 PI. Using DOSBox will let you let you adjust speed as many earlier games have speed issues, and you are on a very fast computer. DOSBox can also be configured to have it's virtualized MPU401 be in intelligent mode so you don't need to mess with SoftMPU. Yes, it's not pure DOS mode, but you are trying to run really early DOS games on hardware that might have been released after Vista came out.

Well its a good thing I also want to use the MT32-Pi as a General MIDI synth. Either way I'm putting that aside for now, until I get my StarTech cable.

Quick update on the situation. Its the damn Prolific chipset cable that was the culprit!

I got a Startech cable with the FTDI chipset and BAM! Works first try, I'm listening to the KI Theme being piped from my Win 98 PC right now.