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macOS marks the . and .. entries in each directory of a FAT filesystem as both directory and hidden. I'm not sure if this is compliant with the FAT spec, but every other OS I've seen has these marked as only directory. Impulse Tracker both uses . and .. as the only way to navigate "up" in its file browser, and also hides hidden directories. The end result is that if you copy samples over from a Mac and navigate to them, you get stuck in that directory.
The fix is to patch the attribute mask used in the call to INT 21h, Function 4Eh ("Find First File") to allow hidden directories as well. This patch fixes the sample browser, module browser, and instrument browser. Here it is:
--- IT_DISK.ASM 2024-10-20 05:27:26.000000000 -0500
+++ IT_DISK2.ASM 2026-05-29 01:49:46.000000000 -0500
@@ -1502,8 +1502,8 @@
D_LoadFileNameUpdateCurrentFile:
Mov DX, Offset AllFilesMask
- Mov CX, 10h ; Directories
- Mov BX, CX
+ Mov CX, 12h ; Directories
+ Mov BX, 10h
Call D_LoadFileNames4
Mov AX, NumEntries
@@ -5035,7 +5035,7 @@
Pop DS
Mov DX, Offset AllFilesMask
- Mov CX, 10h
+ Mov CX, 12h
Mov AH, 4Eh
Int 21h
@@ -5142,7 +5142,7 @@
Push CS
Pop DS
Mov DX, Offset AllFilesMask
- Mov CX, 10h
+ Mov CX, 12h
Mov AH, 4Eh
Int 21h
@@ -8853,7 +8853,7 @@
Push CS
Pop DS
Mov DX, Offset AllFilesMask
- Mov CX, 10h
+ Mov CX, 12h
Mov AH, 4Eh
Int 21h
If you're using some other DOS software and are seeing weird issues with directories copied from a Mac, this might be why...
Last updated 29 May 2026