720K External Drive  (250-1061)      Installation       Faxback Doc. # 5257

Adding Tandy's 720K External Disk Drive to your computer as a secondary
disk drive significantly increases the amount of disk storage.  This 3 1/2"
floppy disk drive supports all standard MS-DOS version 2.11.24 and ROM BIOS
commands and uses the 3.5", 80 track microfloppy diskettes.

* 720K bytes formatted storage, 1M byte unformatted

* Uses 3 1/2", double-sided, double-density diskettes

* Connects to a computer via a cable

* Front loading, horizontally-mounted

The external disk drive connects directly to your computer by the cable
from the drive's rear panel.

CONNECTING THE DISK DRIVE

Caution should be exercised when using the disk drive in low humidity
environments to prevent damage to electronic parts by static electricity
being discharged through them.  Before proceeding further, discharge any
static electricity build-up by touching a grounded metal object.

1. Turn off power to all equipment.  Disconnect the power cord form the
   electrical outlet.  If the computer is on, you could damage the central
   processing unit, as well as your external disk drive.

2. Connect the external disk drive's cable to the EXTERNAL DRIVE connector
   on the rear panel of the computer and to the disk drive.

INSERTING THE DISKETTE

Storing your files on diskettes gives you unlimited data file storage
space.  The disk drive uses a 3 1/2", soft sectored, double sided, double
density, 80-track microfloppy diskette (26-417 or 26-418).

1. Follow the instructions in your computer operation manual for powering
   up the system.

   Cover the write-protect notch (square hole in the upper right corner) on
   the diskette when you want to change information on the diskette.
   Otherwise, the disk drive can not write (change information) on the
   diskette.  Move the small tab (normally red or black) down to write
   enable the diskette or move it up to write-protect.  The rule-of-thumb
   is that "If you can see through it, you can't write to it."

2. Insert the diskette with the label side up into the disk drive insertion
   window.

   The LED indicator will light while the drive is in use.  Push in the
   eject button below the insertion window to remove the diskette.

   Before turning off power to the system, be sure to remove the diskette.
   Leaving it in the drive may result in loss of the contents of the
   diskette.

   For instructions on using data diskettes, making backups and formatting
   a diskette, refer to the first part of "A Practical Guide to the Tandy
   1000 EX."

ACCESSING INFORMATION

Information can be accessed from your secondary disk drive and copied to
the 5-1/4" internal drive of the computer.

To access the secondary drive, give the drive reference in the command or
pathname. For example, you might type:

       DIR B:    or B:\PROGRAM

A special function key is used to boot a diskette in the secondary drive
which is designated as Drive B.  Press [F3] during bootup after you hear
the beep to swap drives and change the secondary drive's reference to Drive
A.

For details on using software with your disk drive, refer to the first part
of "A Practical Guide to the Tandy 1000 EX."

CARE AND MAINTENANCE

Your disk drive is designed to be free from periodic maintenance when it is
operated within normal operation duty.

   * Five-year design component life
   * MTBF (mean-time-between-failure) equals 10,000 hours or more with
     power on for typical usage

It is recommended that you clean the magnetic head with a cleaning disk to
maintain reliability of the data.

If some of the parts in the disk drive are operated in a specially heavy
duty condition, or if it is operated over 5 years, it is recommended that
you have the unit serviced by a qualified Radio Shack technician.

Do not apply excessive impact or drop the disk drive on the desk.

(dtc/BKL-01/23/96)