Toshiba APLEX4 Series Original Instruction page 11

Service Manual
Connection board schema
CPU – Screen/Keyboard
(1) Screen
Serial connector to the CPU with power and data. It has its
own controller, only receives data from the CPU using an
special protocol, in the future can be replaced by other
type (i.e. tactile) without modifying the CPU PCB.
(2) Selection controller
Serial connector to the CPU with power and data. As the
screen it has its own controller.
(3) CPU PCB (behind)
Control the communication with the screen and keyboard
and with the connection board controls the input, outputs,
solenoid valves and piston sensors.
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