Telephonic communications – Telephone line or system combined with diverse electrical... – Having transmission of a digital message signal over a...
Patent
1983-08-31
1987-07-14
Heckler, Thomas M.
Telephonic communications
Telephone line or system combined with diverse electrical...
Having transmission of a digital message signal over a...
H04M 1100
Patent
active
046807888
ABSTRACT:
A control and switching device which links a remote terminal by modems over telephone lines to a local central processing unit (CPU) and a local computer console terminal is disclosed. The device, which is coupled by separate lines to the modem at the local site, the local console and the TTY and ASYNC ports of the CPU, includes a microprocessor, a memory, logic circuits and a switch assembly. The switch assembly includes first, second and third switches which are interlocked and which allow three different levels of remote access of the remote terminal. When the first switch is depressed, the device is powered down, the remote terminal has no access to either the TTY or ASYNC ports of the CPU and the local console is hardwired through the device to the TTY port of the CPU. When the second switch is depressed, the local console is hardwired to the TTY port of the CPU and the remote terminal is electrically connected to the ASYNC port of the CPU. When the third switch is depressed, the local console and the remote terminal both have access to either the TTY port of the ASYNC port of the CPU. A variety of firmware commands stored in the device, some of which may be applied by the local console and some by the remote terminal, depending on which switch is depressed, provide a number of different operating modes, the modes including a conversation mode wherein the CPU is locked out and the local console and remote terminal can communicate directly with each other.
REFERENCES:
patent: 3889062 (1975-06-01), Epstein
patent: 4048672 (1977-09-01), Seiden et al.
patent: 4356545 (1982-10-01), West
patent: 4484306 (1984-11-01), Kulczyckyj et al.
Cordeiro Craig A.
Graham John P.
Data General Corporation
Frank Jacob
Heckler Thomas M.
Kriegsman Irving M.
Wall Joel
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