If you wanna get your #PicoGUS working under Windows 3.1, I think I've figured it out:
* Install GUS drivers through the Control Panel > Device Drivers / Browse to C:\ULTRASND\WINDOWS
* This always gives an error. https://www.vogons.org/viewtopic.php?t=52561 says to copy stuff from C:\ULTRASND\WINDOWS\SYSTEM to C:\WINDOWS\SYSTEM but I got away with just trying to do it again and choosing "Current Driver."
* Select your ULTRASND IRQ (5 by default) for >BOTH< GF1 & MIDI!
Don't forget pgusinit! #IndiPTips