EP0442615A2
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EP
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A communications adapter
Assignee: International Business Machines Corp
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Filing: 1991-01-18
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Granted: —
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Expires: 2011-01-18
Abstract
Abstract A serial communications adapter 22 provides an interface to physical communications ports 32,34. A scheduler executing on the adapter schedules tasks at different priority levels, so that time-critical tasks are performed quickly enough to prevent data loss. Data to be transmitted or received through a communications port is stored in buffers on the adapter, and data and command communications between the adapter and the host system are preferably performed over a DMA channel.
Inventors
- 👤 John Thurman Adkins
- 👤 James Stanley Pogorzelski
- 👤 Jacqueline Hegedus Wilson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 06:55
CPC Classifications
G; G06; G06F; G06F9/00; G06F9/06; G06F9/46; G06F9/48; G06F9/4806; G06F9/4843; G06F13/00; G06F13/38; G06F13/10; G06F13/12; G06F13/122
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
96 words
A method for controlling data transfer between a host system (10) and a plurality of communications ports (32,34), comprising the steps of: defining a plurality of tasks for performing data transfer between the ports and an intermediate memory (30), and between the intermediate memory and the host system; assigning priorities to the defined tasks; scheduling tasks (70) to be performed in response to events which occur at the ports and within the host system; and when a task is completed, selecting (62) to be performed next a task having the highest priority of all scheduled tasks.
Claim 2
Dependent Claim
23 words
The method of Claim 1, wherein a task is performed for all ports for which it is scheduled using a round robin strategy.
Claim 3
Dependent Claim
38 words
The method of Claim 1 or 2, wherein said scheduling step includes the step of: providing a table (50) having an entry for each defined task, wherein tasks are scheduled by writing information to the corresponding table entry.
Claim 4
Dependent Claim
43 words
The method of Claim 3, wherein at least one entry in the table has a plurality of subentries each corresponding to a respective port, and wherein the task is scheduled to be performed for a port by writing information to the corresponding subentry.
Claim 5
Dependent Claim
12 words
The method of Claim 4, wherein each subentry comprises one data bit.
Claim 6
Dependent Claim
43 words
The method of Claim 3, 4 or 5, wherein at least one entry in the table represents a count of the number of times the corresponding task has been scheduled, and wherein a task is scheduled by incrementing the value in the entry.
Claim 7
Independent Claim
27 words
The method of any preceding Claim, wherein the events which cause tasks to be scheduled comprise hardware interrupts raised by the host system or by the ports.
Claim 8
Dependent Claim
21 words
The method of Claim 7, wherein the events which cause tasks to be scheduled further comprise the execution of scheduled tasks.
Claim 9
Dependent Claim
78 words
A communications adapter (22) for interfacing a plurality of communications ports (32,34) with a host system (10), comprising: an interface to the host system (24); an intermediate memory (30); a processor (28) for controlling operation of the adapter; a plurality of communications ports (32,34); a bus (26) connecting said host interface, said intermediate memory, said processor and said communications ports; and means (28,30) for scheduling execution of a plurality of communications tasks to be executed by said processor.
Claim 10
Dependent Claim
35 words
The adapter of Claim 9, further comprising means for assigning each communications task a priority level, and wherein scheduled tasks having a higher priority level are performed before scheduled tasks having a lower priority level.
Claim 11
Dependent Claim
34 words
The adapter of Claim 9 or 10, wherein said scheduling means includes a table (50) having entries corresponding to said tasks, and wherein tasks are scheduled by writing information to the corresponding table entries.
Claim 12
Dependent Claim
28 words
The adapter of Claim 11, further comprising means for writing information to the table entries in response to interrupts generated by the host system and said communications ports.
Claim 13
Dependent Claim
16 words
The adapter of Claim 11 or 12, wherein executing tasks write information to the table entries.
Claim 14
Dependent Claim
46 words
The adapter of Claim 11, 12 or 13, wherein at least one table entry contains a plurality of bits each corresponding to a respective communications port, and wherein a task is scheduled to be performed for one of said ports by writing to its corresponding bit.
Claim 15
Dependent Claim
32 words
A computer system having a host system (10) including a central processor (12) and main memory (14); and an adapter (22) as claimed in any of claims 9 to 14 interfaced therwith.
References Cited (Backward Citations)
No citation records indexed.
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