Monkey Island I & II work just fine! Thanks!
My setup here is sort of odd, but I don't see why it wouldn't work with a normal serial port and sound card.

hw:
emachines 1300 nForce 430 AM2/Athlon64
Intel HDA
Moschip serial/parallel port low profile PCI-Express card
COM1 connected to Roland SK-50 (keyboard w/same serial interface as SC-55mkII) RS232C-2 setting

software:
Windows 98SE (DOS 7.1)
SBEMU
HimemX
STNDOSIN.EXE -a (Moschip driver)
*all software below from the softmpu-master.zip that you provided:
jemm386
jload qpiemu.dll
softmpu /MPU:330 /OUTPUT:COM1

Great work, watching with interest!

The same system also works great with a more modern motherboard:
Asus B75M-PLUS w/1GB of DDR3 RAM and no PCI/PCIE cards at all.
It has pin headers for one COM port and one LPT port on board, and there are working drivers for the NIC (RTL8168) for use with mtcp.

A bit off topic, but Cloudschatze's midi-over-serial patches for Duke Nukem 3D and Doom work with SBEMU too!
With the previous emachines system, the serial IF pcie card drivers use IRQ 5 and 7, apparently causing crashes when sound effects and MIDI are used at the same time.
Now I am using an original SC-55.
The SC-55 only has standard 5 pin MIDI ports, but I found that if you connect the COM port to a Yamaha MU-80, MIDI data is transmitted over the Yamaha's MIDI OUT, which you can connect to the SC-55.
Now I have the SC-55's THRU connected to a PC with MUNT, playing Monkey Island 2.

Baron von Riedesel wrote on 2023-12-10, 11:27:

The current SoftMPU v1.91 requires MS EMM386 or Qemm v7.03+. […]
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The current SoftMPU v1.91 requires MS EMM386 or Qemm v7.03+.

A modified SoftMPU that should also work with Jemm386/JemmEx is attached.

The binary was created with MSVC v7 and Masm v6.11d - I don't have MSVC v6..

I don't know if it works, though -I tried with the SB16 emulation of both Qemu and VBox, but SoftMPU tells that it is unable to detect the MPU at port 0x330. I'm no expert in such topics - I guess one has to try it with true SB hardware ( which I didn't do as of yet ).

Anyway, if someone is interested and willing to test, go on and please report the results.

Note that to activate the Jemm port trapping, one has to load QPIEMU.DLL first:

C:\>JLOAD QPIEMU.DLL

I tried with two configs on virtualbox:
1. latest sbemu with softmpu piggybacked to the virtual sb card: Exception 06
2. softmpu directly on COM1: Not detected by any game despite loading fine

this is great stuff! i tested this out on physical hardware (pentium p45c 75mhz) using the softmpu /output:comx switch and it worked fine. i first tried jemmex v5.79, but softmpu port trapping failed to activate which isn't too surprising since jload v5.85 was included with the modified softmpu. replaced jemmex with v5.85 and everything was good to go.