| 摘要 |
A host computer system allowing the utilization of designated characters as flow control characters and also the utilization of the same designated characters as ordinary data. During the transfer of data from the host computer to the terminal, the operating system controlling the host computer first disables the use of the designated characters as flow control characters, starts the transfer of information to the terminal, performs operations to determine whether or not the terminal is approaching the point where it can no longer receive data, and enables the utilization of the designated characters as flow control characters when the terminal reaches the latter point. The enabling of the designated characters for use as flow control characters allows the terminal to signal to the computer when it has received too much data and control the flow of data to the terminal using the designated flow control characters. When the operating system is preparing to receive large amounts of data from the terminal, it disables the flow control utilization of the designated characters so that these characters can be transmitted from the terminal to the computer as data. The operating system is of the multiprogram type and the enabling and disabling of the flow control is accomplished by an application program making requests to an I/O handler program that is directly controlling the terminal via operating system calls.
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