Communications circuit having an interface for external address decoding

Claim 3

The method of claim 1 and further comprising the step of generating a failed comparison signal if all of the segment addresses within the inter-ring routing information of the data frame do not match the predetermined segment address.

Claim 4

The method of claim 1 and further comprising the step of determining whether the data frame is a broadcast frame.

Claim 5

The method of claim 3 and further comprising the step of indicating that all bridge stations between the first and second data ring networks should copy the data frame if the data frame is determined to be a broadcast frame.

Claim 6

The method of claim 3 and further comprising the step of comparing any segment address within the inter-ring routing information of the data frame to a predetermined segment address if the data frame is determined not to be a broadcast frame.

Claim 7

The method of claim 5 and further comprising the step of copying the data frame into the second adapter circuit if any of the segment addresses within the inter-ring routing information of the data frame matches the predetermined segment address.

Claim 8

The method of claim 5 and further comprising the step of generating a failed match condition if all of the segment addresses within the inter-ring routing information of the data frame do not match the predetermined segment address.

Claim 9

The method of claim 1 and further comprising the step of determining whether the data frame includes an escape sequence therein.

Claim 10

The method of claim 8 and further comprising the step of generating a failed comparison signal if an escape sequence exists within the data frame.

Claim 11

A bridge station for communicating from a first data ring network to a second data ring network a data frame containing a fixed destination address and fixed inter-ring routing information including at least one segment address, wherein each data ring network includes a plurality of locally addressable processing stations, the bridge station comprising: input means for receiving the data frame originating in the first data ring network; protocol handler circuitry, comprising: a first address register, connected to the input means, for storing the destination address of the data frame; a second address register for storing a pre-assigned address; and an intra-ring comparator, connected to the first address register and the second address register, for comparing the destination address to the pre-assigned address; a local data bus, connected to the input means, for storing the data frame externally from the protocol handler circuitry; external address comparison circuitry operating externally and independently from the protocol handler circuitry, comprising: a first segment address register, connected to the local data bus, for storing inter-ring routing information; a second segment address register for storing a predetermined segment address; an inter-ring comparator, connected to the first segment address register and the second segment address register, for comparing any segment address within the inter-ring routing information to the predetermined segment address; and interface terminals for passing comparison signals to the protocol handler circuitry; and decision logic responsive to both the protocol handler circuitry and the external address comparison circuitry for causing the data frame on the local data bus to be stored into a memory for presentation to the second data ring network.

Claim 12

A bridge station for communicating from a first data ring network to a second data ring network a data frame containing a fixed destination address and fixed inter-ring routing information including at least one segment address, wherein each data ring network includes a plurality of locally addressable processing stations, the bridge station comprising: input means for receiving the data frame originating in the first data ring network; protocol handler circuitry, comprising: a first address register, connected to the input means, for storing the destination address of the data frame; a second address register for storing a pre-assigned address; and an intra-ring comparator, connected to the first address register and the second address register, for comparing the destination address to the pre-assigned address; a local data bus, connected to the input means, for storing the data frame externally from the protocol handler circuitry; external address comparison circuitry operating externally and independently from the protocol handler circuitry, comprising: a first segment address register, connected to the local data bus, for storing inter-ring routing information; a second segment address register for storing a predetermined segment address; an inter-ring comparator, connected to the first segment address register and the second segment address register, for comparing any segment address within the inter-ring routing information to the predetermined segment address; and interface terminals for passing comparison signals to the protocol handler circuitry; and decision logic responsive to both the protocol handler circuitry and the external address comparison circuitry for causing the data frame on the local data bus to be stored into a memory for presentation to the second data ring network.

Claim 13

The bridge station of claim 10 wherein the protocol handler circuitry and the external address comparison circuitry operate independently.

Claim 14

The bridge station of claim 10 wherein the interface terminals pass match and fail signals responsive to the results of the comparison in the inter-ring comparator.

Claim 15

The bridge station of claim 10 wherein the data frame containing a fixed destination address and fixed inter-ring routing information including at least one segment address remains unmodified while communicated from the first data ring network to the second data ring network.

Claim 16

The bridge station of claim 10 wherein a first data frame stored on the local bus is overwritten by a second data frame received by the input means upon a failed comparison of both the protocol handler circuitry and the external address comparison circuitry.

Claim 17

The bridge station of claim 10 wherein segment addresses within the fixed inter-ring routing information are stored in sequence and a match of the predetermined segment address with the last segment address in sequence initiates an intra-ring transfer using the fixed destination address.