Oki 3390, Microline Printer, 3391 Operation Description, Element Description, Circuit Description

2.OPERATION DESCRIPTION

2.1Element 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)SN75189

An RS-232C standard line receiver

(3)SN75188

An RS-232C standard line driver.

(4)2764

An 8 kbyte ROM that contains the serial interface control program.

(5)HM6264

An 8192-byte static RAM used as a message buffer.

2.2Circuit Description

A block diagram is shown in Figure C-2-1.

C – 2