A1 10
FRONT PANEL
DISPLAY AND KEYBOARD
(2020 140)
The Front Panel Display and Keyboard assembly (A1 10)
is
divided into two functional sections.
Numeric display and annunciators
Keyboard
NUMERIC DISPLAY AND ANNUNCIATORS
This section of the assembly contains twelve common anode 7-segment numeric display units (DS1-DS12),
two green LED's (DS37 and DS38), and
a
maximum of twenty-four yellow LED's (DS13-DS36).
The twelve 7-segment LED's are mounted side-by-side, with space between each third digit from the right.
The corresponding cathode segments of the 7-segment LED's are connected. and the drive signals come
from the segment drivers 03 through 010. The signals to drive the digits come from the digit drivers
located on the Front Panel Logic board
(A1 1 1
).
The twenty-four yellow LED's (DS13-DS36) are divided into three groups of 8 LED's each. The anodes of
all
LED's in each group are connected. The cathode of each LED in a group are connected to one of the
segment drivers (03-010). With this arrangement each group of annunciator lights can be regarded
as
simi-
lar to one 7-segment LED. The digit drives for the 3 groups of annunciator lights also come from the
Front Panel Logic board
(A1 11).
The two green LED's (DS37 and DS38) are driven by 01 and 02. When these LED's light they indicate
that GATE and CONVERTER SEARCH are in operation.
KEYBOARD
This section of the assembly makes provision for a maximum of 25 (single-pole double-throw) switches,
of which only 21 are used. The switches are arranged in
a
4
row by 6 column matrix, with the extra switch
taking the row
4
column 7 position. The columns are connected to +5V through the resistor network
(RN1) on the Front Panel Logic board (A1 11).
The keyboard
is
continuously scanned. The signals scanning the keyboard are derived from A1 11. To scan
the keyboard the
4
rows are grounded sequentially. When
a
row
is
grounded, and
a
k@
in that row
is
pushed, one of the columns will be grounded. This information
is
sent to the All 1 board where key
debouncing
is
performed.
Scans by ArtekMedia © 2007
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