Here you can download the original PCMIDI utilities and manual as well as the newer version quick setup guide.
Keep in mind no drivers are needed for DOS.
Windows 3.x , 9x and ME include the "Roland MPU-401" driver which works perfectly with PCMIDI.

Original PCMIDI manual
Original PCMIDI utilities disk image and files (for historical reasons)
New PCMIDI Quick Setup Guide (all you really need!)
Windows 9x/ME MPU-401 MultiPort drivers (gets rid of annoying "this device is used by another application" message)
All of the above files in a single package

User-made game patches:

These are patches made by users and getting added as they get released/discovered.
They are mainly patches that fix games locked resources or bugs and they usable by every MPU out there not just PCMIDI.
If you know any that should be added to this list please contact Leo so they can be mirrored here.

Patches made by kykypyza

These patches remove the IRQ2/9-only restriction in the following games:
Innocent Until Caught
Princes Maker
Princess Maker 2
David Wolf
It Came from the Desert


Patches made by ripsaw8080

The following patches fix music playback in BIOFORGE when using a Music Quest PCMIDI:
Bioforge ver.f1.01
Bioforge ver.f1.02s