Communications: electrical – Digital comparator systems
Patent
1975-06-09
1977-01-11
Shaw, Gareth D.
Communications: electrical
Digital comparator systems
G06F 300, G06F 304
Patent
active
040030326
ABSTRACT:
A system for and a method of automatically determining the terminal characteristics and line speed of an unknown asynchronous line terminal are disclosed. The automatic terminal and line speed detector (ATLSD) is a feature that is selectably addable to an existing communications multiplexer module (CMM) of an existing communications controller (CC). The CMM provides the means for selectively intercoupling one of a plurality of different line terminals (LT) at a plurality of remote sites to a central processor (CP) at a central site. The ATLSD includes an ATLSD Table in which are stored a plurality of multibit terminal identifier characters (TICs), each of which TICs defines the terminal identity, terminal characteristics and line speed of the LT that is identified thereby. When ATLSD is desired, a command from the CP places the ATLSD in the scan mode and loads a count transition number (CTN) and a character transition number (KTN) into associated registers of the CMM. The first character that is transmitted by the LT that is to be identified by the ATLSD is sampled by a transition detector for Mark to Space and Space to Mark transitions with a real-time sample counter initiated by the first Mark to Space transition caused by the initial Start (S.sub.T) bit. As the sample count accrues, it is compared to the currently addressed one of the maximum sample counts that are associated with and are a part of each of the terminal identifier characters that are stored in successive address locations of the ATLSD Table. When the current sample count equals the currently compared to maximum sample count that is stored in and associated with the currently addressed terminal identifier character, the ATLSD Table location address is incremented to address the next subsequent terminal identifier character (the terminal identifier characters that define a set of line terminals are stored in the ATLSD Table in an ascending order of successively increasing maximum sample counts). Several sets of terminal identifier characters may be stored in the ATLSD Table. When the number of signal transitions that is detected by the transition detector equals the CTN, i.e., CTN = 0, the address incrementer is disabled and no further change in the ATLSD Table location address is made. However, the transition detector continues counting transitions until the character transition number (KTN), as determined by the last signal transition of the first character, is reached. When the KTN is reached, the ATLSD Table is referenced to read out a portion of the currently addressed terminal identifier character which portion is then transferred to the associated CMM registers from which the CMM conditions its associated logic to accommodate the terminal characteristics and line speed of the identified LT.
REFERENCES:
patent: 3311889 (1967-03-01), Birmingham
patent: 3560937 (1971-02-01), Fischer
patent: 3618037 (1971-11-01), Wollum
patent: 3699525 (1972-10-01), Klavins
patent: 3771135 (1973-11-01), Huettner
patent: 3828325 (1974-08-01), Stafford
patent: 3909791 (1975-09-01), Wouter van den Berg
Austin Michael M.
Barrett William G.
Grace Kenneth T.
Nikolai Thomas J.
Shaw Gareth D.
Sperry Rand Corporation
Thomas James D.
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