Access control to a shared resource in an asynchronous system

Claim 3

The system of claim 1 wherein said first local line control means contains means for generating a bus acknowledge pass signal and wherein said highest priority bus master device further includes synchronization means operating upon the condition that said highest priority bus master device has no outstanding bus request signal for synchronizing said bus acknowledge signal with said highest priority bus master device control timing signals before said first line control means generates a bus acknowledge pass signal to send to the next downstream bus master device.

Claim 4

The system of claim 2 wherein said highest priority bus master device further includes inhibiting means for preventing the generation of said bus acknowledge pass signal for a period of time prior to the local cycle time for issuing a local bus request signal, wherein said period of time is sufficient to allow said synchronization means to stabilize.

Claim 5

The system of claim 3 wherein said inhibiting means continues to inhibit the passage of said bus acknowledge pass signal to said next downstream device when said local bus master issues a local bus request signal and said bus acknowledge pass signal is inactive.

Claim 6

In a system for resolving contention among a plurality of asynchronous bus master devices connected to a common bus, wherein said system includes bus arbitrator means connected to receive a bus request signal from any one of said bus master devices desiring the use of said bus and wherein each of said bus master devices are serially connected in order of priority with the highest priority bus master device directly connected to said bus arbitrator means so that said highest priority bus master device is first to receive a signal issued by said bus arbitrator means indicating that said bus is free to use, and in the case wherin said highest priority bus master device has no outstanding bus request signal, said highest priority bus master device propagates said signal indicating that bus is free to downstream bus master devices in accordance with priority, the method of enabling a bus master device receiving said signal indicating that the bus is free to seize control of said bus without a delay to synchronize said signal indicating that the bus is free to local bus master control timing signals comprising the steps of: upon the issuance of said bus request signal to said bus arbitrator means by a particular bus master device, issuing a local bus request signal for use in the local input line control section of that particular bus master device; combining said local bus request signal with said signal indicating that the bus is free to generate a bus request granted signal, said bus request granted signal being issued within said line control section without first synchronizing said signal indicating that the bus is free with local bus master control timing signals.

Claim 7

In a system for resolving contention among a plurality of asynchronous bus master devices connected to a common bus, wherein said system includes bus arbitrator means connected to receive a bus request signal from any one of said bus master devices desiring the use of said bus and wherein each of said bus master devices are serially connected in order of priority with the highest priority bus master device directly connected to said bus arbitrator means so that said highest priority bus master device is first to receive a signal issued by said bus arbitrator means indicating that said bus is free to use, and in the case wherin said highest priority bus master device has no outstanding bus request signal, said highest priority bus master device propagates said signal indicating that bus is free to downstream bus master devices in accordance with priority, the method of enabling a bus master device receiving said signal indicating that the bus is free to seize control of said bus without a delay to synchronize said signal indicating that the bus is free to local bus master control timing signals comprising the steps of: upon the issuance of said bus request signal to said bus arbitrator means by a particular bus master device, issuing a local bus request signal for use in the local input line control section of that particular bus master device; combining said local bus request signal with said signal indicating that the bus is free to generate a bus request granted signal, said bus request granted signal being issued within said line control section without first synchronizing said signal indicating that the bus is free with local bus master control timing signals.

Claim 8

The method of claim 5 further including the step of: synchronizing said signal indicating that the bus is free with local timing signals before passing said signal indicating that the bus is free to the next downstream device.

Claim 9

The method of claim 6 further including the step of: inhibiting the passage downstream of said signal indicating that the bus is free whenever the local bus master acts to seize control of said bus.