Apparatus for providing multiple controller interfaces to a standard digital modem and including separate contention resolution

Claim 2

In a communication system, having a modem for providing an interface to a communication link, said communication system further having a plurality of controllers whereby each of said controllers is connected to said modem via an interface apparatus, and further wherein said modem and said controllers comply with a predetermined protocol, said interface apparatus comprising: (a) first means, for providing a local medium to transfer signals between said controllers and said modem; (b) second means, for providing an arbitration path between said controllers when at least one of said controllers is requesting access to said first means; (c) first interface means, connected to said first means, for interfacing said modem to said first means, said first interface means implementing simple retiming of signals on said first means to maintain the predetermined protocol between said modem and said first interface means; and (d) a plurality of second interface means, each of said second interface means being connected to said first and second means and to a corresponding controller, for interfacing each of said plurality of controllers to said first and second means, each of said interface means implementing a controller-associated multi-state state machine which responds to signals on said first and second means further responds to signals from the corresponding controller, each of said second interface means maintaining the predetermined protocol between the second interface means and the corresponding controller.

Claim 3

An interface apparatus according to claim 1, wherein each of said second interface means implements a controller-associated multi-state state machine having six states, identified as S-idle, S-arbitrate, S-copy, B-wait, B-arbitrate, and B-pad.

Claim 4

An interface apparatus according to claim 2, wherein said first interface means is further connected to said second means.

Claim 5

An interface apparatus according to claim 3, wherein said first interface means simulates a modem, said modem being effectively disconnected from said first interface means, whereby said simulation functions in a local loopback mode.

Claim 6

An interface apparatus according to claim 4, wherein said predetermined protocol is a standard as defined by IEEE standard, 802.4-(1989).

Claim 7

An interface apparatus according to claim 2, wherein said first interface means simulates a modem, said modem being effectively disconnected from said first interface means, whereby said simulation functions in a local loopback mode.

Claim 8

An interface apparatus according to claim 2 wherein said predetermined protocol is a standard as defined in IEEE standard 802.4-(1989).

Claim 9

An interface apparatus according to claim 6 wherein said predetermined protocol is a standard as defined in IEEE standard, 802.4-(1989).

Claim 10

An interface apparatus according to claim 1, wherein each of said second interface means implements a first controller-associated multi-state state machine having three states, identified as F-empty, F-active, and F-overrun, cascaded into a second multi-state state machine itself having three states; identified as T-idle, T-arbitrate, and T-source.

Claim 11

An interface apparatus according to claim 9, wherein the first and second controller-associated multi-state machines form a third controller-associated multi-state machine having the nine states.

Claim 12

An interface apparatus according to claim 1, wherein each of said second interface means implements a first controller-associated multi-state state machine having three states, identified a F-empty, F-active, and F-overrun, cascaded into a fourth multi-state state machine itself having six states, identified as T-idle, T-arbitrate, T-source, T-sync, T-wait, and T-busy.

Claim 13

An interface apparatus according to claim 11, wherein the first and second controller-associated multi-state machines form a third controller-associated multi-state machine having the eighteen states.

Claim 16

An apparatus as in claim 13, in which each of said controller-associated multi-state state machine has six distinct states identified as S-idle, S-arbitrate, S-copy, B-wait, B-arbitrate, and B-pad.

Claim 17

An apparatus, as in claim 13, in which said controller-associated state machine is a composite of a cascaded first and second state machines, the first state machine having three distinct states, identified as F-empty, F-active, and F-overrun, and the second state machine having three distinct states, identified as T-idle, T-arbitrate, and T-source.

Claim 18

An apparatus, as in claim 15, in which said first and second state machines form a third state machine having the nine distinct states.

Claim 19

An apparatus, as in claim 13, in which said controller-associated state machine is a composite of a cascaded first and second state machines, the first state machine having three distinct states, identified as F-empty, F-active, and F-overrun, and the second state machine having six distinct states identified as T-idle, T-arbitrate, T-source, T-sync, T-wait, and T-busy.

Claim 20

An apparatus, as in claim 17, in which said first and second state machines form a fourth state machine having the eighteen distinct states.

Claim 21

An apparatus, as in claim 13, in which said modem is replaced by a timing source and logic means for simulating a modem functioning in a local loopback mode.

Claim 22

An apparatus, as in claim 13, wherein said shared bus comprises: signaling paths which are in one-to-one functional correspondence with the signaling paths specified in the standard modem-controller interface of section 10 of IEEE Std 802.4-1989 (otherwise known as the IEEE 802.4G interface).

Claim 23

An apparatus, as in claim 14, in which said modem is replaced by a timing source and logic means for simulating a modem functioning in a local loopback mode.

Claim 24

An apparatus, as in claim 21, wherein said shared bus comprises: signaling paths which are in one-to-one functional correspondence with the signaling paths specified in the standard modem-controller interface of section 10 of IEEE Std 802.4-1989 (otherwise known as the IEEE 802.4G interface).

Claim 25

In a communication system, having a first plurality of modems for providing an interface to a communication link, said communication system further having a second plurality of controllers whereby each of said controllers is connected to said plurality of modems via an interface apparatus, and further wherein each of said modems and each of said controllers comply with a predetermined protocol, said interface apparatus comprising: (a) bus means, for providing a medium to transfer signals between each of said controllers and each of said modems; (b) a plurality of first interface means each of said first interface means connected to a corresponding modem and, connected to said bus means, for interfacing each of said modems to said bus means, each of said first interface means implementing a modem-associated multi-state state machine which responds to signals on said bus to maintain the predetermined protocol between the corresponding modem and the first interface means; (c) a plurality of second interface means, each of said second interface means being connected to said bus means and to a corresponding controller, for interfacing each of said plurality of controllers to said bus means, each of said second interface means implementing a controller-associated multi-state state machine which responds to signals on said bus means and further responds to signals from the corresponding controller, each of said second interface means maintaining the predetermined protocol between the second interface means and the corresponding controller; (d) connecting means, connected to each modem and to each of said second interface means, for providing a common clocking signal to each modem and each of said second interface means; and (e) contention bus means, for providing an arbitration path between said controllers when at least one of said controllers is requesting access to said bus means.

Claim 26

In a communication system, having a first plurality of modems for providing an interface to a communication link, said communication system further having a second plurality of controllers whereby each of said controllers is connected to said plurality of modems via an interface apparatus, and further wherein each of said modems and each of said controllers comply with a predetermined protocol, said interface apparatus comprising: (a) bus means, for providing a medium to transfer signals between each of said controllers and each of said modems; (b) a plurality of first interface means each of said first interface means connected to a corresponding modem and, connected to said bus means, for interfacing each of said modems to said bus means, each of said first interface means implementing a modem-associated multi-state state machine which responds to signals on said bus to maintain the predetermined protocol between the corresponding modem and the first interface means; (c) a plurality of second interface means, each of said second interface means being connected to said bus means and to a corresponding controller, for interfacing each of said plurality of controllers to said bus means, each of said second interface means implementing a controller-associated multi-state state machine which responds to signals on said bus means and further responds to signals from the corresponding controller, each of said second interface means maintaining the predetermined protocol between the second interface means and the corresponding controller; (d) connecting means, connected to each modem and to each of said second interface means, for providing a common clocking signal to each modem and each of said second interface means; and (e) contention bus means, for providing an arbitration path between said controllers when at least one of said controllers is requesting access to said bus means.

Claim 27

An interface apparatus according to claim 23, wherein each of said second interface means implements a controller-associated multi-state state machine having six states, identified as S-idle, S-arbitrate, S-copy, B-wait, B-arbitrate, and B-pad.

Claim 28

An interface apparatus according to claim 24, wherein said predetermined protocol is a standard as defined by the IEEE standard 802.4-(1989).

Claim 29

An interface apparatus according to claim 23, wherein each of said second interface means implements a first controller-associated multi-state state machine having three states, identified as F-empty, F-active, and F-overrun, cascaded into a second multi-state state machine itself having three states, identified as T-idle, T-arbitrate, and T-source.

Claim 30

An interface apparatus according to claim 26, wherein the first and second controller-associated multi-state machines form a third controller-associated multi-state machine having the nine states.

Claim 31

An interface apparatus according to claim 23, wherein each of said second interface means implements a first controller-associated multi-state state machine having three states, identified as F-empty, F-active, and F-overrun, cascaded into a fourth multi-state state machine itself having six states, identified as T-idle, T-arbitrate, T-source, T-sync, T-wait, and T-busy.

Claim 32

An interface apparatus according to claim 28, wherein the first and second controller-associated multi-state machines form a third controller-associated multi-state machine having the eighteen states.