US 4,541,043 AGranted

Resource granting process and device in a system comprising autonomous data processing units

AssigneeThomson-CSF

InventorsJean C. Ballegeer, Duyet H. Nguyen

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Abstract

A process and an apparatus for the granting of a resource in a system comprising at least two antonomous data processing units in which each unit can request the granting of the resource by means of an individual interface circuit. The interface circuits are coupled to a multiple conductor channel of the binary type which can assume first and second logic states. Each unit is also associated with a particular number and a priority level. For allocating the resource to one of the units, a sequence of three conditional control signals generated in autonomous manner by the individual interface circuits is used, namely a first signal, whose positioning in the second logic state indicates that at least one unit is requesting the granting of the resource, a second signal, whose positioning in the first logic state indicates that the resource has not been allocated to any of the units, and a third signal, whose transition from the first logic state to the second logic state simultaneously authorises the start of a competition between the requesting units, followed by the choice of only one of the said units for the granting of the resource, and inhibits the requests of other units. The reverse transition of the third signal after a predetermined period validates the chosen unit and leads to the display on the multiple conductor system of a binary word representing the number of the chosen unit, as well as allowing new requests for the resource.

Claims18

Dependent claims

In a data processing system comprising at least two autonomous data processing units and a resource which may be used by said units and wherein each of said units is assigned an identification number and a priority level for requesting the use of said resource, and wherein each unit is provided with an interface means and a multiple-conductor channel to connect said interface means, a method for granting said resource to at least one of said units in a decentralized manner, comprising the steps of:

providing communications between said units, said communications consisting of first, second and third conditional control signals each capable of assuming a first or second logical state, a first binary word representing the priority level of the requesting unit which has the highest priority level, a second binary word representing the identification number of the unit which has been granted the use of said resource,
determining whether any of said units has requested said resource, said request being signaled autonomously by any of said interface means positioning said first conditional control signal in said second logical state,
determining whether said resource has been granted to any of said units, said granting being signaled by the interface means associated with the unit which has been granted said resource positioning said second conditional control signal in said second logical state,
determining whether said unit is requesting said resource while at least one other unit is also requesting said resource thus necessitating a competition run among said requesting units to determine which unit will be granted said resource, said competition run being signaled by said interface means positioning said third conditional control signal in said second logical state,
inhibiting other requests for said resource during said competition run,
resolving said competition run by sampling said first binary word and calculating whether the priority level of said unit is higher than the priority levels of the other units within said run,
validating the winning unit of said competition run after a predetermined period of time by the interface means associated with said winning unit transmitting said indentification number in said second binary word,
positioning said third conditional control signal in said first logical state to allow new requests for said resource and a new competition run.

5 more elements

In a data processing system comprising at least two autonomous data processing units and a resource which may be used by said units and wherein each of said units is assigned an identification number and a priority level for requesting the use of said resource, a device for granting said resource to at least one of said units in a decentralized manner, comprising:

multiple-conductor connecting means for providing communications between said units, said connecting means comprising:
first, second, and third bidirectional connecting conductors respectively conveying first, second, and third conditional control signals, each capable of assuming a first or second logical state;
a first group of conductors for conveying a binary word representing the priority level of the requesting unit which has the highest priority level;
a second group of conductors for conveying a binary word representing the identification number of the unit which has been granted the use of said resource;
interface means associated with each of said units and connected between said unit and said multiple-conductor connecting means for determining which one or which plurality of said units shall be granted said resource, comprising:
(a) means for determining whether any of said units has requested said resource, said request being signaled autonomously by any of said interface means positioning said first conditional control signal in said second logical state;
(b) means for determining whether said resource has been granted to any of said units, said granting being signaled by the interface means associated with the unit which has been granted said resource positioning said second conditional control signal in said second logical state;
(c) means for determining whether said unit is requesting said resource while at least one other unit is also requesting said resource thus necessitating a competition run among said requesting units to determine which unit will be granted said resource, said competition run being signaled by said interface means positioning said third conditional control signal in said second logical state;
(d) means for inhibiting other requests for said resource during said completition run, (e) means for resolving said competition run by sampling said first group of conductors and calculating whether the priority level of said unit is higher than the highest priority level carried on said first group of conductors;
(f) means for validating the winning unit of said completition run after a predetermined period of time by the interface means associated with said winning unit transmitting said indentification number on said second group of conductors;
(g) means for positioning said third conditional control signal in said first logical state to allow new requests for said resource and a new competition run, and wherein said interface means is coupled to said multiple-conductor connecting means by transmitting logic elements with semiconductor junctions of the open collector type in such a way that the second logic level preponderates over the first logic level.

8 more elements

Dependencies are inferred from the claim text.