Chapter 10Terminal Handling

A common type of peripheral device found on 4.4BSD systems is a hardware interface supporting one or more terminals. The most common type of interface is a terminal multiplexer, a device that connects multiple, asynchronous RS-232 serial lines, which may be used to connect terminals, modems, printers, and similar devices. Unlike the block storage devices described in Section 6.2 and the network devices to be considered in Chapter 11, terminal devices commonly process data one character at a time. Like other character devices described in Section 6.3, terminal multiplexers are supported by device drivers specific to the actual hardware.

Terminal interfaces interrupt the processor asynchronously to present input, which ...

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