Local network interface for use in multi-station word processing system and a data communications network

Claim 2

A local network interface for use in a network for enabling each of a plurality of data processing stations to communicate with one another via a communications medium (52), in which the local network interface is operatively connected between said communications medium (52) and said data processing stations, characterised in that said local network interface comprises a processor (10), a direct memory access (DMA) controller (12) operatively connected to said processor (10), means for controlling communications (14, 36) operatively connected between said communications medium (52) and said processor (10) and memory means (16) operatively connected to said processor (10), to said means for controlling communications (14, 36) and to. said DMA controller (12) so that the data residing in said memory means (16) may be accessed for transmission to said communications medium (52) via said local network interface and may be updated therefrom.

Claim 3

A local network interface in accordance with claim 1, characterised in that said means for controlling communications (14, 36) includes a transmitter state controller (36) for allowing said means for controlling communications (14, 36) to be actuated without intervention by said processor (10).

Claim 4

A local network interface in accordance with claim 2, characterised in that said means for controlling communicatinns (14, 36) includes a communications controller (14) operatively connected to said transmitter state controller (36).

Claim 5

A local network interface in accordance with claim 3, characterised in that said means for controlling communications includes an encoder (42) operatively connected to said communications controller (14) for encoding data to be transmitted into a standard format.

Claim 6

A local network interface in accordance with claim 4, characterised in that said standard format of encoded data to be transmitted is the Manchester code format.

Claim 7

A local network interface in accordance with any one of claims 1 to 5, characterised in that said memory means includes a random access memory (RAM) (16) and refresh circuitry (18) operatively connected thereto for maintaining the data therein.

Claim 8

A local network interface in accordance with any one of claims 1 to 6, characterised in that it further comprises a programmable read only memory (PROM) (32) operatively connected to said DMA controller (12) and said memory means (16), said PROM (32) having instructions therein for controlling data transfer over said communications medium (52).

Claim 9

A local network interface in accordance with claim 7 characterised in that it further comprises means (60, 64) for controlling communications among the processors of two or more data processing stations operatively connected to said processor (10) and to said memory means (16).

Claim 10

A local network interface in accordance with claim 8 characterised in that said means for controlling communications among the processors of two or more data processing stations includes an interprocessor communications controller (20).

Claim 11

1 0. A data communications network for use in a data processing system characterised in that it comprises a plurality of data processing stations (50, 58) adapted to transmit and to receive data via a common communications channel (52), a communications channel having a first segment and a second segment,. each of said segments being adapted to transfer data from one of said plurality of data processing stations operatively connected thereto to another of said plurality of data processing stations operatively connected thereto and one (64) of said plurality of data processing stations being a nodal point data processing station operatively connected between said first segment and said second segment so that data generated by one of said plurality of data processing stations (50, 58) operatively connected to one of said segments may be transferred to another of said plurality of data processing stations (50, 58) operatively connected to the other of said segments via said nodal point data processing station (64).

Claim 12

1 0. A data communications network for use in a data processing system characterised in that it comprises a plurality of data processing stations (50, 58) adapted to transmit and to receive data via a common communications channel (52), a communications channel having a first segment and a second segment,. each of said segments being adapted to transfer data from one of said plurality of data processing stations operatively connected thereto to another of said plurality of data processing stations operatively connected thereto and one (64) of said plurality of data processing stations being a nodal point data processing station operatively connected between said first segment and said second segment so that data generated by one of said plurality of data processing stations (50, 58) operatively connected to one of said segments may be transferred to another of said plurality of data processing stations (50, 58) operatively connected to the other of said segments via said nodal point data processing station (64).

Claim 13

1 1 . A data communications network in accordance with claim 10 characterised in that one of said plurality of data processing stations (58) is directly operatively connected to said first of said segments and another of said plurality of data processing stations (58) is directly operatively connected to said second of said segments.

Claim 14

A data communications network in accordance with claim 11 characterised in that all of said data processing stations (50, 58) including said nodal point data processing station (64), are substantially identical.

Claim 15

13 . A data communications network in accordance with claim 11 or 12 characterised in that each of a plurality of data processing stations (50) includes at least one terminal operatively connected to a module (60), said module (60) being operatively connected to said channel (52).

Claim 16

A data communications network in accordance with claim 11 characterised in that it further comprises an independent intelligent device operatively connected to one of said segments of said communications channel for exchanging data with any of said plurality of data processing stations operatively connected thereto.

Claim 17

A data communications network in accordance with claim 14 characterised in that said independent intelligent device is a computer.

Claim 18

A data communications network for use in a data processing system characterised in that it comprises a plurality of data processing stations (50, 58) adapted to transmit and to receive data via a common communications channel (52), a first communications channel adapted to transfer data from one of said plurality of data processing stations (50, 58) operatively connected thereto to another of said plurality of data processing stations (50, 58) operatively con nected thereto, a second communications channel adapted to transfer data from one of said plurality of data processing stations (50, 58) operatively connected thereto to another of said plurality of data processing stations (50, 58) operatively connected thereto and, a nodal point data processing station (64) operatively connected between said first communications channel and said second communications channel so that data generated by one of said plurality of data processing stations (50, 58) operatively connected to one of said communications channels (52) may be transferred to another of said plurality of data processing stations (50, 58) operatively connected to the other of said communications channels (52) via said nodal point data processing station (64).

Claim 19

A data communications network for use in a data processing system characterised in that it comprises a plurality of data processing stations (50, 58) adapted to transmit and to receive data via a common communications channel (52), a first communications channel adapted to transfer data from one of said plurality of data processing stations (50, 58) operatively connected thereto to another of said plurality of data processing stations (50, 58) operatively con nected thereto, a second communications channel adapted to transfer data from one of said plurality of data processing stations (50, 58) operatively connected thereto to another of said plurality of data processing stations (50, 58) operatively connected thereto and, a nodal point data processing station (64) operatively connected between said first communications channel and said second communications channel so that data generated by one of said plurality of data processing stations (50, 58) operatively connected to one of said communications channels (52) may be transferred to another of said plurality of data processing stations (50, 58) operatively connected to the other of said communications channels (52) via said nodal point data processing station (64).

Claim 20

A data communications network in accordance with claim 16 characterised in that said nodal point data processing station (64) is one of said plurality of data processing stations.

Claim 21

A data communications network or local network interface in accordance with any one of claims 1 to 17 characterised in that said communications channel (52) is a coaxial cable.