Hard Disk Ccontroller Board (250-1007)  Installation   Faxback Doc. # 2022

Since your computer should have one memory expansion board already within it,
preferably in the extreme left-hand slot as you face the front of the mac-
hine, we suggest that this board be installed in the extreme right-hand slot
to allow suitable room for the two cables.

1. Turn off all equipment. If any unit is on, you can damage the integrated
   circuits on either the controller board or within the computer itself.
   Allow a minimum of 10 seconds to pass before any board is either inserted
   or removed from the Tandy 1000.
2. Repeat the procedure of discharging any potentially dangerous static
   electricity build-up by touching a grounded metal object before handling
   the controller board or the CPU.
3. Remove the 2 screws on the front on the main unit. Remove the cover by
   sliding it away from the rear of the unit, parallel to the computer.
4. Rotate the chassis so that the fan faces you. Locate the option slot cover
   furthest to your left as you face the rear of the unit. Remove the sheet
   metal screw from this cover. Tilt the metal strip away from you and lift
   the strip so that the tab on the panel clears the bottom of the slot.
   Store the cover in a safe place for possible future replacement.
5. See Figure 4. Insert the free ends of both cables into the open slot from
   the inside of the computer. Guide the cables through so that the board is
   positioned over the third edge connector socket. Insert the tab on the
   bottom of the controller board mounting bracket into the vacated slot on
   the rear of the computer chassis. At the same time, apply even downward
   pressure, engaging the edge-connector of the board into the socket. Align
   the entire board so that the U-shaped cutout on the top of the board's
   bracket is positioned over the screw-hole on the rear of the chassis.
   Replace the screw you removed before and tighten it to secure the board.
   Do not over tighten the screw.
6. Before replacing the cover of the computer, examine the main circuit
   board. Toward the front of the unit, directly below the slots of the
   speaker panel, you will see a gold colored, three-pronged bracket
   approximately 1/2" square. If your unit does not have this bracket, con-
   tact your Radio Shack Computer Center to arrange for installation of one.
   Grasp the short wires which protrude from each of the ribbon cable plugs
   and slide the terminal of each onto one of the prongs of the bracket.
7. Replace the top cover, securing it with the screw previously removed.

CONNECTIONS TO THE HARD DISK
1. Refer to Figures 5 and 6 for the following cable connections to your
   primary or secondary hard disk.
2. There are generally three sockets on the rear of the hard disk unit.
   Assuming this to be your first external hard disk, or Drive C, connect the
   cable with the wider of the two plugs to the socket on the disk drive
   marked CONTROLLER IN. If your cable has a thin red stripe on one edge,
   position the stripe to the right as you face the rear panel of the drive.
3. The cable with the narrow plug in then inserted into the socket marked
   DATA IN. Also position the red stripe to the right. In both cases, the
   ribbon cable should exit the plug in a downwards fashion.
4. If you have already connected you first external disk, Drive C, and this
   is your secondary, Drive D, the additional DATA cable, equipped with the
   narrow plugs, must be inserted into the second narrow socket on the board,
   adjacent to the one used for Drive C. This cable is also routed beneath
   the strain-relief clamp and through the same slot in the rear panel of the
   Tandy 1000. Then the cable is inserted into the DATA IN socket of Drive D.
5. The Tandy secondary hard disk is supplied with an interconnecting cable,
   about 7 inches long, which is routed between the CONTROLLER OUT socket on
   Drive C and the CONTROLLER IN socket on Drive D.

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