Interrupt 21h Function 7156h

Changes the name of the given file or directory to the new name.

mov ax, 7156h           ; Rename File
mov dx, seg OldName     ; see below
mov ds, dx 
mov dx, offset OldName
mov di, seg NewName     ; see below
mov es, di 
mov di, offset NewName
int 21h

jc  error

Parameters

OldName
Address of a null-terminated string specifying the original name of the file or the directory to rename. Long filenames are allowed.
NewName
Address of a null-terminated string specifying the new name for the file or the directory. The function will fail if this parameter specifies an existing file or directory. The new name must not specify a drive different than the original drive. Long filenames are allowed.

Return Value

Clears the carry flag if successful. Otherwise, the function sets the carry flag and sets the AX register to an error value.