Oki Microline 390 Maintenance Manual - 3. Theory of Operation
3. THEORY OF OPERATION
3.1 Electrical Operation
This
the electrical operation of the printer circuits.
3.1.1
The block diagram of the printer circuit is shown in Figure 3-1.
The control board consists of the microprocessor and its peripheral circuits, the drive circuits, paper
end sensor and interface connector.
The power to the control board is provided from the power supply board via the connector cord.
The power to the other electrical parts is distributed via the connectors in the control board.
3.1.2
Microprocessor and its peripherals circuits
The microprocessor is the nucleus of the control circuit. Its peripheral circuits operate under
program control by this microprocessor. The
ports of the microprocessor are connected to
the address bus, data bus, and control lines.
(2) Program ROM (Q12)
The program ROM contains the control program for the printer. The microprocessor operates
by execution of this control program.
(3)
RAM
and
and
are option.
The RAM stores data such as print data which has been received.
3-1