When I recently tested my freshly configured 286 PC with a few period-appropriate games, I encountered a strange issue with Prince of Persia 2. Everytime I launched the game via PRINCE.EXE, I was greeted with the message: Couldn’t find NISMIDI.DAT.
So I tried switching the music output to PC Speaker as a test. This time, the message changed to Couldn’t find NISDIGI.DAT. Interestingly, when all sound was set to PC Speaker, the game ran flawlessly. But as soon as Adlib or Sound Blaster sound was enabled, those error messages reappeared.
After some research, I discovered the root of the problem: in my MS-DOS 5.0 setup, the default setting in CONFIG.SYS was FILES=10. Prince of Persia 2 doesn’t handle this well—it requires at least FILES=30. Once I updated the line in CONFIG.SYS accordingly and rebooted the system, everything worked perfectly with Sound Blaster sound enabled.