Transmitting commands over a serial link
First Claim
1. Apparatus for generating commands in a system wherein multi-bit characters are continuously sent from a sender to a receiver to acquire character synchronization, said apparatus comprising:
- register means for providing a multi-bit idle character;
bit modifying means connected to said register means for changing selected bits of said multi-bit idle character for forming a command character which is a modification of said multi-bit idle character; and
multiplexing means for forming an ordered set of characters, said ordered set having said multi-bit idle character as a first character and said command character as a second character.
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Accused Products
Abstract
An apparatus and method for transmitting commands over a serial link having a switch intermediate a channel and a control unit wherein continuous sequences of idle characters (K.28.5) are sent over the link for maintaining character synchronization. Commands and response information is sent between ports of the switch and the channel and/or the control unit by modifying every other idle character to a modified idle character to which a command or response function has been assigned. In the modification, a selected number of the bits of the idle character are held invariant, and only those bits are varied which form data characters according to the rules of the 8B/10B encoding method. Code points for a total of 124 modified idle characters are disclosed to which a separate command or response may be assigned.
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Citations
22 Claims
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1. Apparatus for generating commands in a system wherein multi-bit characters are continuously sent from a sender to a receiver to acquire character synchronization, said apparatus comprising:
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register means for providing a multi-bit idle character; bit modifying means connected to said register means for changing selected bits of said multi-bit idle character for forming a command character which is a modification of said multi-bit idle character; and multiplexing means for forming an ordered set of characters, said ordered set having said multi-bit idle character as a first character and said command character as a second character. - View Dependent Claims (2, 3)
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4. An apparatus for receiving synchronizing multi-bit characters, said apparatus comprising:
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a recognition circuit having an input for receiving an ordered set and an output for providing a FUNCTION OUT message, said recognition circuit having detection means for detecting a first idle character in said received ordered set and latch means for providing said FUNCTION OUT message responsive to a second character in said received ordered set; a first detector in said detection means for detecting an idle character having a first disparity; and a second detector in said detection means for detecting an idle character having a second, opposite disparity. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11)
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12. A method of selecting a second character of an ordered set wherein the first character of said ordered set is an idle character and the second characters is a command character, said method comprising the steps of:
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a. establishing said idle character as a base character; b. arranging all valid 8B/10B data characters in sequence such that the first 8B/10B data character has the maximum number of its least significant bits in the same pattern as the base character and the last 8B/10B data character in the sequence has none of its least significant bits in the same pattern as the base character; and c. selecting the number of 8B/10B data characters in the sequence as the number of command characters desired such that the maximum number of least significant bits of the command characters are invarient from the base character.
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13. A data transmission apparatus synchronized by the continuous transmission of multi-bit characters, said data transmission apparatus comprising:
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a switch having at least two ports; and a switch controller for controlling switching between said ports by said switch; each of said ports including an input for receiving data characters transmitted to said port and an output for sending data characters transmitted from said port; each of said ports further including a recognition circuit having an input for receiving an ordered set of said multi-bit characters from its attached link and an output connected to said switch controller for providing to said switch controller a FUNCTION OUT message, said recognition circuit having detection means for detecting a first idle character in said received ordered set, and latch means for providing said FUNCTION OUT message responsive to a second character in said received ordered set. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification