Priority data handling system and method

Claim 3

A method as described in claim 1, wherein: said comparing step is carried out until a lack of correspondence at any said station between bits for any said bit position is detected to terminate the access request for said station and for permitting access in the event that no lack of correspondence is detected before the last bit of said frame is compared.

Claim 4

A method as described in claim 2, wherein: said comparison is conducted using binary numbers and access is granted to the last said station having a binary one in the said bit position of its said number then being compared when a binary zero appears on said channel in said bit position in said frame for comparison.

Claim 5

A method as described in claim 1, wherein: said assigning step comprises assigning to each said station a plurality of said unique numbers, each said number for each station representing a different level of priority selectable by said station for use in said comparison step; and further including a step of selecting by said station desiring access to said channel which of said numbers will be presented for comparison according to the level of priority desired.

Claim 6

A data handling system comprising: a plurality of data handling devices, each said device being connectable via a communications channel for communication with a common controller on an interrupt basis by issuing a request for access thereto on the communications channel; each said data handling device having an assigned interrupt number and also having means, effective when issuing a said request for access, for comparing said number with said other interrupt numbers presented on said channel in connection with conflicting requests for access by other data handling devices in said system and for proceeding with, or abandoning such request according to the result of such comparison; said data handling devices being connected to a common data bus which is connected at one end to said controller and which serves as said communications channel; each said data handling device being adapted to signal an interrupt condition to said controller by changing the DC voltage conditions on said commmon data bus; and said controller is adapted to solicit interrupt requests by issuing, serially by bit on said data bus, a predetermined coded frame to which any data handling device requiring access is adapted to respond by entering into each bit position in said frame a corresponding bit from its assigned interrupt number, followed by comparing said corresponding bit with the contents of that bit position after all requesting devices have entered their associated bits, and terminating or continuing said request for access according to the result of said comparison as determined by said comparing means.

Claim 7

A data handling system comprising: a plurality of data handling devices, each said device being connectable via a communications channel for communication with a common controller on an interrupt basis by issuing a request for access thereto on the communications channel; each said data handling device having an assigned interrupt number and also having means, effective when issuing a said request for access, for comparing said number with said other interrupt numbers presented on said channel in connection with conflicting requests for access by other data handling devices in said system and for proceeding with, or abandoning such request according to the result of such comparison; said data handling devices being connected to a common data bus which is connected at one end to said controller and which serves as said communications channel; each said data handling device being adapted to signal an interrupt condition to said controller by changing the DC voltage conditions on said commmon data bus; and said controller is adapted to solicit interrupt requests by issuing, serially by bit on said data bus, a predetermined coded frame to which any data handling device requiring access is adapted to respond by entering into each bit position in said frame a corresponding bit from its assigned interrupt number, followed by comparing said corresponding bit with the contents of that bit position after all requesting devices have entered their associated bits, and terminating or continuing said request for access according to the result of said comparison as determined by said comparing means.

Claim 8

A system as claimed in claim 5, in which: each said data handling device includes an interrupt register adapted to contain the assigned interrupt number, and a select latch settable in response to said predetermined frame, said interrupt register being operable to drive its contents serially onto said bus in response to the set condition of said select latch, and said select latch being reset in response to a comparison result indicating that the currently compared bit of the assigned interrupt number is binary zero while the corresponding bit on said bus is binary one, thereby terminating the access request of the associated device.

Claim 9

A system as claimed in claim 5, in which: each said data handling device includes two interrupt registers, one or the other register being selectable according to the occurrence of a high or low priority interrupt request within the device.

Claim 10

A system as claimed in claim 6, in which: said interrupt register includes two sections, one being selectable according to the occurrence of a high or low priority interrupt request within the device, the other being common to both classes of request.

Claim 11

A system as claimed in claim 5 in which: interrupt numbers are uniquely associated with said devices and said controller is arranged to reSpond to the number remaining on said bus at the end of said predetermined frame to select the associated device for processing of its interrupt request.

Claim 12

A system as claimed in claim 6, in which: interrupt numbers are uniquely associated with said devices and said controller is arranged to respond to the number remaining on said bus at the end of said predetermined frame to select the associated device for processing of its interrupt request.

Claim 13

A system as claimed in claim 7, in which: interrupt numbers are uniquely associated with said devices and said controller is arranged to respond to the number remaining on said bus at the end of said predetermined frame to select the associated device for processing of its interrupt request.

Claim 14

A system as claimed in claim 8, in which: interrupt numbers are uniquely associated with said devices and said controller is arranged to respond to the number remaining on said bus at the end of said predetermined frame to select the associated device for processing of its interrupt request.