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.