IBM XT 286 Operation Manual page 126

and press Enter, and continue until the in-use light on
the external drive comes on. When the Ught comes on,
you know that the last drive letter entered is the letter
of the external drive.
Be extremely careful to specify the correct drive letter
when using DOS commands such as FORMAT and
ERASE (DEL) to avoid unintentionally destroying
data.
IBM PC Network Program
If you plan to use your 3.5 inch External Diskette Drive
with the IBM PC Network program, make sure that you
do not use the same drive letter DOS assigns to your
external drive for a network device. For example, if
DOS assigns drive E to your external drive, you may
not assign a network device name as E if you want to
access your external drive while using the network.
Notes to Experienced Users
Wammg: Do not write on a 360KB diskette in your
1.2MB drive if you intend to use that diskette in a
360KB drive.
Support for 3.5 Inch External Diskette Drives is
provided through the use of installable device drivers.
For DOS to install the device drivers, three fUes must
be present on any diskette or fixed disk from which
DOS is started;
. EXDSKBIO.DRV
The EXDSKBIO.DRV file is an extension to BIOS
that provides support for external diskette drives.
The driver is installed when DOS is started and
remains resident for AT systems only. Copy the
EXDSKBIO.DRV file from the Device Dnver
diskette to your self-starting diskette.
4-72 3.5 Inch External Diskette Drive