Hal Communications DKB-2010 Instruction Manual Download

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HAL DKB-2010 EXTENDED MEMORY OPTION

Introduction

The HAL 64/128 Key Buffer option extends the memory capacity of the DKB-2010 Dual Mode Keyboard

to 64 or 128 keystrokes, depending on the model chosen. With the buffer installed, the operator is free to
type for an extended period at a rate greater than the keyboard transmission speed without losing

characters.

Buffer operation is controlled by the shifted CQ, AUX and HERE IS keys . Typing a shifted HERE IS clears

the buffer memory. A shifted AUX turns the memory output off, allowing characters to accumulate in the
buffer for later transmission. Typing a shifted CQ turns the memory output on; the stored keystrokes are
then passed to the keyboard logic circuitry. Complete operating instructions are given in Section 3.

A feature of special importance is that the buffer stores keystrokes rather than individual characters. As a

result, the QBF (quick brown fox), identifier, CQ and AUX messages occupy only a single location in the
memory. It is possible, for example, to press the QBF key as many as 64 (or 128) times. Each keystroke will

be stored, and the keyboard will repeat the entire quick brown fox test message as many times as the key
was pressed.

Installation of the buffer requires no wiring changes in the keyboard. The buffer circuit board is fitted

with card-edge connectors and simply plugs in between the keyswitch board and the wiring harness

connector. Complete installation instructions are given in Section 2.

Installation

You will find it very easy to install the buffer in your keyboard by following the steps listed below.

TO PREVENT DANGEROUS ELECTRICAL SHOCK, UNPLUG THE KEYBOARD FROM THE AC OUTLET
BEFORE PROCEEDING. 115 Volt (230 V) AC is exposed at several points within the cabinet.

1st Stand the keyboard on its right end. Remove the three screws from the lip of the bottom cover at the

rear of the unit. Remove the screw from the center of the front edge of the bottom plate. Slide the bottom
plate back to free it from the front lip of the cabinet and lay it flat on the table. The logic board remains

attached to the bottom panel.

2nd The large circuit board remaining inside the cabinet is the keyswitch board. It is held into the cabinet

with five slotted-head screws – two at the upper end, two at the lower end, and one in the center toward
the rear of the cabinet. Remove these five screws, starting with the bottom ones. As you remove the upper
screws, hold the circuit board to prevent it from falling from the cabinet.

3rd Swing the upper end of the circuit board away from the cabinet. As you do so, reach behind the

board and pull the BUFFER FULL lamp from the plastic lens. Cut the lamp leads off as close as possible to
the circuit board. The lamp may be discarded, as it will be replaced by the new lamp connected to the buffer

circuit board.

4th Carefully detach the circuit board connector from the contact fingers at the rear edge of the board.

5th Plug the keyswitch board into the card edge connector mounted on the buffer circuit card. Note that

the buffer board will be beneath the keyswltch board when the keyboard is in its normal operating position.
Then plug the buffer board into the card edge connector previously removed from the keyswitch board.
Make certain that the connector has not been reversed – the yellow and red leads should be closest to the
power transformer when the keyswitch board is reinstalled.

6th Return the keyswitch board (with the buffer circuit card attached) to its original position in the

cabinet. As you do, reach beneath the board and insert the lamp connected to the buffer board into the lens

from which the old BUFFER FULL lamp was removed. Then secure the keyswitch board to the cabinet with
the five screws removed during disassembly.