Connection To Computer; Location Of Controller Circuit Board; Installing The Controller - Texas Instruments 990 Installation And Operation Manual

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7. Connect plug P2 (9-pin socket) of the data cable to jack J2 on the rear of the display
unit.
8. On the power supply/logic board in the display unit is a video compensation circuit. This
circuit has two gain settings selected by switch or jumper plug configuration. Remove the
top cover of the VDT for access to the gain selector.
9. Set the video compensation circuit to the L position if the length of the cables between
the terminal and the computer is 305 metres
(1000
feet) or more; otherwise, configure
the circuit to the S position.
NOTE
The video compensation circuit should be set for optimum display
clarity regardless of cable length.
2.6 CONNECTION TO COMPUTER
The VDT controller circuit board may be installed in either the main chassis of the computer or
in an expansion chassis that is connected to the computer. In all cases the computer and/or
expansion chassis equipment must be installed and operating properly. Refer to the Computer
System Hardware Reference Manual for computer installation instructions. Before installing the
VDT controller circuit board, reference table 2-2 to verify that the controller on hand supports
the associated VDT(s).
2.6.1 LOCATION OF CONTROLLER CIRCUIT BOARD. The physical location of the circuit
board within either the computer or the expansion chassis determines the CRU address that the
controller circuit board responds to. Therefore, before deciding upon a chassis location for the
new circuit board, determine the address that the system software expects it to recognize. Refer
to the configuration label on the top of the computer chassis to determine the location in the
chassis corresponding to the expected address. Refer to table 2-3 to determine the expansion chassis
corresponding to the base address.
2.6.2 INSTALLING THE CONTROLLER. Once the proper location for the VDT controller
circuit board has been determined, the controller may be installed in the computer or expansion
chassis and connected to the terminal cables. Perform the following steps to complete that
procedure:
I . Set the POWER switch on the front of the computer or expansion chassis to the OFF
position to remove ac power from the unit.
NOTE
The VDT controller circuit board (figure 2-6) has two plastic
pivoted tabs (card ejectors) on the end of the board. This end is
the outside edge of the circuit board. The opposite edge of the
circuit board inserts into the connectors in the computer chassis.
2-9
Digital Systems Division