| 摘要 |
An I/O controller functions to provide management of, control of, while functioning as two "virtual" data link processors for at least two separate types of peripheral terminal units, thus enabling data transfers between a host computer and any selected one of the peripheral terminal units. A commonly shared logic interface, common to both virtual controllers, is selected for use by a Request-Program Array Logic unit which arbitrates the utilization of the common logic by one of two virtual controllers at any given time. A first and second status latch is provided in the common front end interface of the I/O controller whereby each status latch provides status signals to the main host computer system of the state of any one of two virtual controllers which share common interface to a host computer. At the particular time that the host is addressing one of the virtual controllers (for the purpose of initializing communications with that controller) via its status latch register, a path is provided to the I/O microprocessor in the controller such that microprocessor access to that status latch is temporarily inhibited in order to maintain stable status signals for the interrogating host computer.
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