Priority controlled selection of data sets in a data processing system

Claim 3

The method as defined in claim 1 and in which the comparison of the value of the priority criterion signal with the total value produced by the signals present on said path is effected at each requesting functional unit.

Claim 4

The method as claimed in claim 1 wherein the value of the priority criterion signal allocated to any functional unit is a signal identifying the degree of priority of said functional unit by a fixed, predetermined number, signal comparisons being carried out simultaneously at all the requesting functional units in response to a comparison command signal transmitted to all the units in common and provided from the processor or from a functional unit, and disconnection of functional units having a priority less than the functional unit having the highest priority being effected after a comparison period which is the same for all the functional units, connection being established or continued as regards that functional unit for which the result of comparison is zero.

Claim 5

A method as claimed in claim 3 wherein the disconnection is effected by a disconnecting command signal which is provided from the processor, and transmitted simultaneously to all functional units in common.

Claim 6

A method as claimed in claim 3 wherein the disconnection is effected by a disconnecting command signal generated individually in each functional unit after the end of the comparison period.

Claim 7

A method as claimed in claim 1 wherein the value of priority criterion signal allocated to any functional unit is a signal identifying the degree of priority thereof by a fixed predetermined number and its complement, signal comparisons by position or order of magnitude of the state produced on the common communications path being carried out both as regards these numbers and their complements and selection of connection being effected in dependence on the difference between the two comparisons results obtained, one for the value of the number and the other for the value of the complement.

Claim 8

A method as claimed in claim 6 wherein the value of the priority criterion signal is a binary signal and wherein signal comparison is effected for each binary bit by AND-gating the binary state of the common communications path associated with that binary bit with the complement of the corresponding binary bit of the predetermined number and determining the difference between the gating signals for the value of the number and the value of the complement.

Claim 9

A method as claimed in claim 6 wherein the selection is effected in dependence on the sign of the said difference.

Claim 10

A method as claimed in claim 1 wherein the value of the priority criterion signal allocated to any functional unit and identifying the degree of priority thereof is stored in a store adjacent to that functional unit and fed therefrom into the common communications path in response to a feed-in command signal from the common processor.

Claim 11

A method as claimed in claim 9 wherein the value of the priority criterion signals for connection and the feed-in command signals are fed over the common communications path.

Claim 12

The method as defined in claim 1 in which the comparison of the value of the priority criterion signal from the requesting functional unit with the total value of the signals present on said path further comprises the steps of feeding into said common communication path the complement of said value of the priority criterion signals from those functional units which are at the time requesting connection; combining said value of the priority criterion signal of said functional unit with the states on the lines associated with said value of the priority criterion signal of said common communication path to obtain a first comparison number; combining said value of the complement of said priority criterion signal of said functional unit with the states on the lines associated with the value of the complement of said priority criterion signal of said common communication path to obtain a second comparison number; comparing said first comparison number with said second comparison number for selecting for connection the requesting functional unit with the highest priority number and disconnecting requesting functional units with lower priority numbers.

Claim 13

The method as defined in claim 11 in which said value of the priority criterion signals are binary coded.

Claim 14

The method as claimed in claim 12 in which the steps of combining said binary priority criterion signal, and the complement of said binary priority criterion signal, with the binary states on their respective associated lines on the common communication path, comprises the step of exclusive-or gating said binary priority criterion signal, and the complement of said binary priority criterion signal, with the binary states on their respective associated lines on the common communications path.

Claim 15

Apparatus for control of a data processing system whereby priority-controlled selection of one of a plurality of functional units with different connection priorites and which may be simultaneously signalling requests for connection to a common processor allocated thereto is effected, said apparatus including means allocating to each functional unit a value of a priority criterion signal for connection of that unit to said common processor, each such signal being peculiar to the unit to which it is allocated and identifying the degree of priority of said unit; means feeding into a common communication path leading in parallel from all the functional units to the common processor the value of the priority criterion signals and the value of the complement priority criterion signals from those functional units which are, at the time, requesting connection; means comparing the value of the priority criterion signal and the value of the complement priority criterion signal of each functional unit with the total value produced by the composite of the signals present on said path from other functional units and in dependence upon the result of said comparisons being equal to or different from a predetermined value for each functional unit, means for selecting for connection that functional unit, which, at the time, is of highest priority upon an equal comparison, and by disconnecting those functional units of lower priority in which the result of the comparison is different from the predetermined value.

Claim 16

Apparatus for control of a data processing system whereby priority-controlled selection of one of a plurality of functional units with different connection priorites and which may be simultaneously signalling requests for connection to a common processor allocated thereto is effected, said apparatus including means allocating to each functional unit a value of a priority criterion signal for connection of that unit to said common processor, each such signal being peculiar to the unit to which it is allocated and identifying the degree of priority of said unit; means feeding into a common communication path leading in parallel from all the functional units to the common processor the value of the priority criterion signals and the value of the complement priority criterion signals from those functional units which are, at the time, requesting connection; means comparing the value of the priority criterion signal and the value of the complement priority criterion signal of each functional unit with the total value produced by the composite of the signals present on said path from other functional units and in dependence upon the result of said comparisons being equal to or different from a predetermined value for each functional unit, means for selecting for connection that functional unit, which, at the time, is of highest priority upon an equal comparison, and by disconnecting those functional units of lower priority in which the result of the comparison is different from the predetermined value.

Claim 17

The invention as defined in claim 14 wherein the value of the priority criterion signals identifying the priorities are in the form of binary numbers, said apparatus further including at each functional unit, two first gates provided for each position of the binary number allocated to that functional unit; means for applying as the first inputs to said gates the value, or complement of the associated binary bit of the binary number allocated to the funational unit; means for applying as the second inPuts to said gates signals present on value, or complement lines of the common communication path for this bit position; and means for feeding the outputs of the gates respectively to the two control inputs of a multibit binary comparator.

Claim 18

The apparatus as defined in claim 15 wherein the value and complement of each bit of the binary number are respectively connected to two further gates, the putputs of which are connected with the corresponding value line, or complement line of the common communications path and which can be opened by a control circuit in order to feed the binary number and its complement into the common communications path.

Claim 19

Apparatus as defined in claim 16 wherein the first gates and the further gates are AND gates.

Claim 20

Apparatus as defined in claim 16 wherein the first gates are NOR gates and the further gates are NAND gates.

Claim 21

Apparatus as defined in claim 15 and also including a storage device for storing the respective binary number and its complement in the functional unit.