Interrupt 21h Function 71AAh Minor Code 2h

Determines if the specified drive is associated with a path and, if it is, retrieves the associated path.

mov ax, 71aah            ; SUBST
mov bh, 2                ; Query SUBST
mov bl, DriveNum         ; see below
mov dx, seg PathName     ; see below
mov ds, dx
mov dx, offset PathName 
int 21h

jc error

Parameters

DriveNum

Drive to SUBST. This parameter can 1 for A, 2 for B, and so on. Note that DriveNum cannot be 0 to indicate the default drive.

PathName

Pointer to buffer that receives the null-terminated string of the path associated with the specified drive. The buffer must be of MAXPATHLEN size.

Return Values

Clears the carry flag and retrieves the associated path in the specified buffer if successful. Otherwise, the function sets the carry flag and returns an error value in the AX register.