US3735357A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Priority system for a communication control unit
Assignee: International Business Machines Corp
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Filing: 1972-09-19
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Granted: 1973-05-22
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Expires: 1992-09-19
Abstract
Abstract A priority system is described for a communications controller having a large number of attached communication lines. The communication lines are divided into groups of lines having substantially the same service requirements. All lines within a higher priority group will be given service before any service is granted to lines having a lower priority. Within each group, service will generally be accorded to the lines on a first come, first served priority scheme.
Inventors
- 👤 A Maholick
- 👤 F Newlin
- 👤 R Snyder
- 👤 S Stager
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 20:09
CPC Classifications
H; H04; H04L; H04L5/00; H04L5/02; G; G06; G06F; G06F13/00; G06F13/14; G06F13/20; G06F13/32; G06F13/34
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
275 words
In a data communications system of the type having a central processing unit, a plurality of communications lines of a number of different transmission characteristics and each assigned to one of several priority levels together with a communications control unit between said processing unit and said communications lines, said control unit including two storage units, a data path and control means for transferring data to and from said storage units and along said data path, said system also including a scanner base to test the condition of each communications line in a predetermined sequence to receive data from or to transmit data to the tested line, the invention comprising a cycle control system in said control unit having an interrupt mechanism of several levels, a plurality of interrupt registers in said scanner base, there being one interrupt register for each of said priority levels, means to select the one of said interrupt registers which is allocated to the priority of the communications line being scanned, means to gate into said selected interrupt register the address of a communications line being tested by said scanner base when an operation of said communications control unit is necessary to maintain data service to said line and to transmit an interrupt needed signal to said control unit, a priority circuit to transfer to said control unit during an ensuing operation of said interrupt mechanism, the communications line address stored in the highest order priority one of said registers which is occupied, and a circuit for each interrupt register to prevent storing into an occupied register, the line address of another communications line requiring service and having the same priority.
Claim 2
Dependent Claim
275 words
In a data communications system of the type having a central processing unit, a plurality of communications lines of a number of different transmission characteristics and each assigned to one of several priority levels together with a communications control unit between said processing unit and said communications lines, said control unit including two storage units, a data path and control means for transferring data to and from said storage units and along said data path, said system also including a scanner base to test the condition of each communications line in a predetermined sequence to receive data from or to transmit data to the tested line, the invention comprising a cycle control system in said control unit having an interrupt mechanism of several levels, a plurality of interrupt registers in said scanner base, there being one interrupt register for each of said priority levels, means to select the one of said interrupt registers which is allocated to the priority of the communications line being scanned, means to gate into said selected interrupt register the address of a communications line being tested by said scanner base when an operation of said communications control unit is necessary to maintain data service to said line and to transmit an interrupt needed signal to said control unit, a priority circuit to transfer to said control unit during an ensuing operation of said interrupt mechanism, the communications line address stored in the highest order priority one of said registers which is occupied, and a circuit for each interrupt register to prevent storing into an occupied register, the line address of another communications line requiring service and having the same priority.
Claim 3
Dependent Claim
70 words
The invention as set out in claim 1 in which said scanner base also requests a cycle steAling interrupt operation of said interrupt mechanism at a higher interrupt priority level when any communications line being scanned has been set to indicate a need for bit service and cycle stealing control circuits to transfer the address of said communications line being scanned to said control unit independently of said priority registers.
Claim 4
Dependent Claim
247 words
A priority servicing system for a communications control unit of a communications network having a plurality of communications lines of a number of different characteristics, said control unit being controlled by a program stored in a core storage and having at least two levels of interrupt programs, said servicing system comprising a scanner base to test the status of each communications line according to a predetermined sequence for detection of a status requiring the initiation of a bit service program, said scanner base also sensing the termination of at each bit service program if a character service is needed, a plurality of priority registers one for each group of communications lines having a common characteristic, means responsive to detection of the need for initiation of a character service program to store the identification of the line requiring character service in its associated priority register and to signal a request for a lower level interrupt condition to said control unit, an address bus from said priority registers to said control unit, and gating means from each priority register to said address bus, each said gating means being activated jointly by said control unit during the processing of a lower level interrupt, by the prior storing of an address in its associated register and by a non-storage of data condition in all registers having a higher priority, and a circuit for each register to prevent entry of the address of a second communications line into an already occupied register.
Claim 5
Dependent Claim
247 words
A priority servicing system for a communications control unit of a communications network having a plurality of communications lines of a number of different characteristics, said control unit being controlled by a program stored in a core storage and having at least two levels of interrupt programs, said servicing system comprising a scanner base to test the status of each communications line according to a predetermined sequence for detection of a status requiring the initiation of a bit service program, said scanner base also sensing the termination of at each bit service program if a character service is needed, a plurality of priority registers one for each group of communications lines having a common characteristic, means responsive to detection of the need for initiation of a character service program to store the identification of the line requiring character service in its associated priority register and to signal a request for a lower level interrupt condition to said control unit, an address bus from said priority registers to said control unit, and gating means from each priority register to said address bus, each said gating means being activated jointly by said control unit during the processing of a lower level interrupt, by the prior storing of an address in its associated register and by a non-storage of data condition in all registers having a higher priority, and a circuit for each register to prevent entry of the address of a second communications line into an already occupied register.
Claim 6
Dependent Claim
128 words
The invention as set out in claim 3 wherein upon the detection of a need for a bit service in a scanned communications line, said scanner base activates a request to said control unit for a higher level cycle stealing interrupt operation, cycle steal control means active during said higher level interrupt operation to arrest scanning operations of said scanner base and to gate out to said address bus the address of the line for which bit service is requested, a line control word register set by data transmitted from said control unit to said scanner base during said higher level interrupt operations and means in said scanner base to modify the data in said line control word register and return said modified data to said control unit.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |