Oki ML490 Maintenance Manual - Page 128

Appendix C, Rs-232c Serial Interface Board Option, General, Operation Description

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Appendix C RS-232C SERIAL INTERFACE BOARD (OPTION) 1. GENERAL This section describes the operation of the RS-232C Serial Interface board installed in the Printer as an option using a start-stop synchronization and serial communications circuit. This serial interface board is capable of transmitting and receiving simultaneously at speeds up to 19,200 bits per second. Two protocols are available: printer Ready/Busy and X-ON/X-OFF modes. 2. OPERATION DESCRIPTION 2.1 Element Description (1) 80C51 with MASK ROM An eight-bit microprocessor controller that controls the following: (a.) Serial interface protocol and data transfer through a serial port. (b.) Message buffer. (c.) Transmission of parallel data to the printer. (2) 75189 An RS-232C standard line receiver (3) 75188 An RS-232C standard line driver. (4) ROM (No Mount) A 64Kbit ROM that contains the serial interface control program. (5) RAM A 64Kbit static RAM used as a message buffer. 42114101 Rev.1 128 /

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42114101
Rev.1
128 /
Appendix C
RS-232C SERIAL INTERFACE BOARD (OPTION)
1.
GENERAL
This section describes the operation of the RS-232C Serial Interface board installed in the Printer
as an option using a start-stop synchronization and serial communications circuit. This serial
interface board is capable of transmitting and receiving simultaneously at speeds up to 19,200
bits per second. Two protocols are available: printer Ready/Busy and X-ON/X-OFF modes.
2.
OPERATION DESCRIPTION
2.1
Element Description
(1)
80C51 with MASK ROM
An eight-bit microprocessor controller that controls the following:
(a.)
Serial interface protocol and data transfer through a serial port.
(b.)
Message buffer.
(c.)
Transmission of parallel data to the printer.
(2)
75189
An RS-232C standard line receiver
(3)
75188
An RS-232C standard line driver.
(4)
ROM (No Mount)
A 64Kbit ROM that contains the serial interface control program.
(5)
RAM
A 64Kbit static RAM used as a message buffer.