EP0675449A1
Expired / Lapsed
EP
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System and method for controlling an input/output controller of a computing system
Assignee: International Business Machines Corp
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Filing: 1995-03-29
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Granted: —
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Expires: 2015-03-29
Abstract
Abstract A computing system with a SCSI controller includes a SCSI transmission mode selection apparatus and method to switch the transmission line drivers between transmitting in SCSI 1, SCSI 2 or another mode. The controller selects a maximum data transmission rate compatible with each peripheral device connected to the controller. In preferred embodiments a user-defined option code is decoded by the controller to provide the user with control over transmission mode options for the drivers in the controller. Based on the data transmission rate and the selected option, the controller selects the SCSI transmission mode to use for each driver type, acknowledge line or data lines.
Inventors
- 👤 Donald S. Keener
- 👤 Gregory J. Moore
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 17:14
CPC Classifications
G; G06; G06F; G06F13/00; G06F13/38; G06F13/382; G06F13/385; G06F13/40; G06F13/4063; G06F13/4068; G06F13/4072
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
144 words
A method of controlling the data transmission mode of drivers (60, 61) in an input/output controller (11) of a computing system (100), at least one peripheral device (30) being connected to the controller (11) over a transmission line bus (70), and the drivers (60, 61) transmitting signals on the bus (70) from the controller (11) to each peripheral device (30), said method comprising the steps of: selecting for each peripheral device (30) a maximum compatible data transmission rate between the controller (11) and the peripheral device (30); selecting a transmission mode for each peripheral device (30) based on the maximum compatible data transmission rate between the controller (11) and the peripheral device (30) receiving the data transmission; and enabling the drivers (60, 61) to transmit in the selected transmission mode for each peripheral device (30) when transmitting from the controller to the peripheral device.
Claim 2
Dependent Claim
75 words
A method as claimed in claim 1, wherein said data transmission rate selecting step comprises the steps of: interrogating each peripheral device (30) for the peripheral device's maximum data transmission rate; receiving the maximum data transmission rate from each peripheral device (30); and setting the maximum compatible data transmission rate for each peripheral device (30) to the controller transmission rate closest to and equal to or less than the peripheral device's maximum data transmission rate.
Claim 3
Dependent Claim
92 words
A method as claimed in claim 1, wherein said data transmission rate selecting step comprises the steps of: sending a proposed data transmission rate from the controller (11) to each peripheral device (30); receiving from each peripheral device a response rate equal to the proposed rate or a maximum peripheral device data transmission rate closest to the proposed rate; and setting the maximum compatible data transmission rate for each peripheral device (30) to the controller transmission rate closest to and equal to or less than the response rate from the peripheral device.
Claim 4
Independent Claim
45 words
A method as claimed in any of claims 1 to 3, further comprising the steps of detecting user defined parameters provided to the controller by the computing system, and taking the user defined parameters into account when selecting the transmission mode for each peripheral device.
Claim 5
Dependent Claim
109 words
A method as claimed in claim 4, wherein said transmission mode selecting step comprises the steps of: detecting whether the maximum compatible data transmission rate exceeds a threshold transmission rate; decoding the user-defined parameters to identify a first transmission mode for data transmission rates exceeding the threshold rate and a second transmission mode for data transmission rates not exceeding the threshold rate; selecting the first transmission mode as the selected transmission mode if the maximum compatible data transmission rate exceeds the threshold transmission rate; and selecting the second transmission mode as the selected transmission mode if the maximum compatible data transmission rate does not exceed the threshold transmission rate.
Claim 6
Independent Claim
71 words
A method as claimed in any preceding claim, wherein said drivers (60, 61) transmit in a plurality of transmission modes including at least an open drain mode, and wherein said transmission mode selecting step comprises the steps of: detecting whether the controller is in a non-data operative phase transmitting signals other than data; and selecting the open drain mode as the transmission mode when the controller is in the non-data phase.
Claim 7
Independent Claim
101 words
A method as claimed in any preceding claim, wherein said drivers transmit in a plurality of transmission modes including at least an open drain mode and a transient pullup mode, and wherein said transmission mode selecting step comprises the steps of: detecting whether the maximum compatible data transmission rate exceeds a threshold transmission rate; selecting the open drain mode as the selected transmission mode if the maximum compatible data transmission rate does not exceed the threshold transmission rate; and selecting the transient pull-up mode as the selected transmission mode if the maximum compatible data transmission rate exceeds the threshold transmission rate.
Claim 8
Independent Claim
58 words
A method as claimed in any preceding claim, wherein the drivers (60, 61) in the controller (11) include multiple sets of drivers, each set of drivers operating in a different transmission mode, and said enabling step comprises the steps of: enabling the set of drivers operating in the selected transmission mode; and inhibiting all other sets of drivers.
Claim 9
Independent Claim
38 words
A method as claimed in any of claims 1 to 8, wherein each driver in the controller operates in any of the transmission modes, and said enabling step enables each driver to operate in the selected transmission mode.
Claim 10
Independent Claim
171 words
An apparatus for controlling the data transmission mode of drivers (60, 61) in an input/output controller (11) of a computer system (100), at least one peripheral device being connected to the controller (11) over an input/output bus (70), and the drivers (60, 61) being arranged to transmit signals, including data, on the bus (70) from the controller (11) to each peripheral device (30), said apparatus comprising: rate selection means for selecting for each peripheral device (30) a maximum compatible data transmission rate compatible with the peripheral device; mode selection means (20) for selecting a transmission mode for the drivers (60, 61) in the controller (11) when the drivers are transmitting to each peripheral device (30), said transmission mode being based, at least in part, on the maximum compatible data transmission rate for the peripheral device receiving the data transmission; and means for enabling the drivers (60, 61) to transmit in the selected transmission mode for each peripheral device (30) when the drivers are transmitting from the controller to the peripheral device.
Claim 11
Dependent Claim
43 words
An apparatus as claimed in claim 10, further comprising: means for detecting user-defined parameters provided to the controller by the computing system; said mode selection means (20) selecting a transmission mode based on the user-defined parameters and the maximum compatible data transmission rate.
Claim 12
Dependent Claim
113 words
An apparatus as claimed in claim 11 wherein said mode selection means comprises: means for detecting whether the maximum compatible data transmission rate exceeds a threshold transmission rate; means for decoding the user-defined parameters to identify a first transmission mode for data transmission rates exceeding the threshold rate and a second transmission mode for data transmission rates not exceeding the threshold rate; means for selecting the first transmission mode as the selected transmission mode if the maximum compatible data transmission rate exceeds the threshold transmission rate; and means for selecting the second transmission mode as the selected transmission mode if the maximum compatible data transmission rate does not exceed the threshold transmission rate.
Claim 13
Independent Claim
100 words
An apparatus as claimed in any of claims 10 to 12, wherein there are a first plurality of drivers in the controller (11) arranged to transmit in a first mode and a second plurality of drivers in the controller (11) arranged to transmit in a second mode, and wherein said enabling means comprises: first enabling means for enabling the first plurality of drivers when the first transmission mode is selected by said mode selection means (20); and second enabling means for enabling the second plurality of drivers when the second transmission mode is selected by said mode selection means (20).
Claim 14
Independent Claim
67 words
An apparatus as claimed in any of claims 11 to 13, further comprising: phase determining means (12) for determining whether the controller (11) is currently transmitting in data or non-data phase; said mode selection means (20) being responsive to the phase determined by said phase determining means (12), the decoded user-defined parameters, and the data rate determined by said rate selection means, to select the transmission mode.
Claim 15
Independent Claim
29 words
An apparatus as claimed in any of claims 10 to 14, wherein there are a plurality of selectable transmission modes, including at least SCSI 1 and SCSI 2 modes.
References Cited (Backward Citations)
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