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1.概述8251可编程通讯接口(以下简称8251)是8080微型计算机系统中主要的外围芯片之一。它是一种典型的串行数据通讯接口,用于实现8080CPU与外部设备之间的串行通讯。例如与电传打字机、盒式磁带机、显示器通讯;也可以通过调制解调器(MODEM)与电话线联接,实现远距离的数据通讯。由于它的通讯格式既可以是同步通讯也可以是异步通讯,既可以作为发送器也可以作为接收器,所以被称为通用同步异步接收发送器,简称为USART。由于它的通讯波特率,
1. Overview 8251 Programmable Communication Interface (hereinafter referred to as 8251) is one of the main peripheral chips in the 8080 microcomputer system. It is a typical serial data communication interface for serial communication between the 8080CPU and external devices. For example, teletypewriter, cassette tape drive, display communications; also through the modem (MODEM) and the telephone line connection, to achieve long-distance data communications. Because of its communication format can be either synchronous communication can also be asynchronous communication, either as a transmitter can also be used as a receiver, so called Universal Synchronous Asynchronous Receiving Transmitter, referred to as the USART. Because of its communication baud rate,