Genicom MatrixPrinter LA36 - Manual (Page 126)

5-39
5.3.9 Control panel control
The control panel has 16 LEDs, 7 push-button switches, a buzzer, and an LSI (MB623829) to control them. The
switch contact signals and LED drive signals are transmitted between the main board and the control panel
through a flat cable. An LED drive signal is issued from the main board to the LSI as serial data which the LSI
converts into parallel data. The switch contact signals are input to the LSI as parallel data which the LSI con-
verts into serial data and issues it to the main board.
The buzzer is driven by the 1-MHz clock signal from MPU (MB90706).
Figure 5.39 Control panel block diagram
MB623829
*OPDOT
*LOAD
*SHIFT
*BKSI
+5V
SGI
*SDIN
BZCLK
Internal
control
circuit
Serial-to-
parallel
converter
Parallel-to-
serial
converter
LEDs
+5V
+5V
Switches
SG1
Buzzer
SG1