Create a MIDI file that uses the portamento effect the way you want it to work and I will test it to see if it works the same way on the Microsoft GS Wavetable Synth and on my Roland Sound Canvas.

Microsoft GS Wavetable Synth is available on every Windows computer.
The problem is to create a MIDI file.
What messages besides the "Portamento On" are required for it to work?
Which banks/programs support it?
Can you do portamento on Sound Canvas?

Check the bottom reply from this thread:

https://www.midi.org/forum/9694-roland-sc-7-portamento

I supplied 6 files that have portamento. Test them out, see what happens!

I did not hear anything like Portamento.
In Heart_of_Fire_DMC.mid and Marble_Gallery_MMP.mid there were only drums.
Perhaps, MS GS Wavetable Synth did not recognize the bank/program combination.

I modified Heart Of Darkness. Microsoft GS does not like LSB 1, so I changed it all to LSB 0. There is no portamento with Microsoft GS. With VirtualMIDISynth, and with MIDI Player, it works as expected. There should be an almost constant portamento from low to high and back to low throughout the song.

Have a listen.

[quotePost id=11367]I modified Heart Of Darkness. Microsoft GS does not like LSB 1, so I changed it all to LSB 0. There is no portamento with Microsoft GS. With VirtualMIDISynth, and with MIDI Player, it works as expected. There should be an almost constant portamento from low to high and back to low throughout the song.

Have a listen.[/quotePost]"Heart Of Fire*" ( Heart Of Darkness is a different Castlevania track that is not in this batch :p )

The Roland Sound Canvas supports portamento and works as expected.
The Microsoft GS Wavetable Synth does not respond to portamento settings.