Int 21H, AH=65H, AL=A1H

4.0 and higher

capitalize counted filename string

AX = 65A1h
DS:DX -> filename string to capitalize
CX = length of string

 CF set on error
AX = error code (see #01680 at AH=59h/BX=0000h)
CF clear if successful

Nonfunctional in MS-DOS 4.00 through 7.10 (Win98) due to a bug (the code sets a pointer depending on the high bit of AL, but doesn't clear the bit before branching by function number). Supported and functional(!) in Novell DOS 7 (Update 15), as well as PC-DOS 7 and OS/2 MVDM

Text based on Ralf Brown Interrupt List Release 61