Information handling system having serial channel to control unit link

• US 4,939,735 A
• Filed: 07/21/1988
• Issued: 07/03/1990
• Est. Priority Date: 07/21/1988
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wiegand, Michael R., Wilson, Lee H., Kubik, Joseph J., Fredericks, Kenneth J.
• Primary Examiner(s): ATKINSON, CHARLES
• Application Number:
  US07/222,679
• Time in Patent Office: 712 Days
• Field of Search: 371/55, 371/57, 371/69, 371/47.1, 371/69.1, 364/200, 364/900
• US Class Current: 714/798
• CPC Class Codes: G06F 11/08 Error detection or correction by redundancy in data representation, e.g. by using checking codes
• CPC Class Codes: G06F 13/122 where hardware performs an I/O function other than control of data transfer
• CPC Class Codes: G06F 13/4226 with asynchronous protocol

Abstract

An information handling system includes a processor with one or more channels for communicating to peripheral devices controlled by peripheral device controllers, and one or more serial data links between the channels and the peripheral controllers. Data is transmitted over the serial data link between the channels and the controllers in a frame format, wherein each frame includes a number of eight-bit characters selected so that all standard parallel interface tag and data lines are transmitted in a single frame with a high degree of error immunity resulting from selection of idle characters and frame start characters having the mutual characteristic that single and double bit errors in the idle characters do not create an erroneous indication of a start character in the system.

Claims

1. An information handling system for processing data communicated between a processor and one or more peripheral devices on a serial data link, comprising:

a processor for processing said data;

one or more channels for communicating between said processor and one or more peripheral device controllers;

one or more peripheral device controllers for controlling one or more peripheral devices in response to signals from said channel in accordance with a predetermined communications protocol;

a serial data link, adapter connected between one of said channels and one or more of said peripheral device controllers for extending the range of communications between said channels and said controllers, said adapter further comprising;

first and second sub-adapters, each communicating with the other across said serial data link and each sub-adapter having transmit and receive sections, said transmit section comprising;

frame generation means responsive to signals received from said channel and said peripheral device controller respectively, said signals conforming to said predetermined protocol, said frame generation means including means for generating one or more unique start frame characters in response to control signals received by said frame generation means;

means for generating predetermined idle characters, said idle characters having an error immune relationship with said start characters, such that idle characters having single and double bit errors transmitted on said serial data link will not be recognized as start frame characters;

an encoder for encoding data for efficient and error free transmission over said data link;

a serializer for converting said encoded data from parallel format to serial format;

link interface and driver means for transmitting serialized encoded data across said serial data link; and

said receive section of each of said sub-adapter, comprising;

a receiver for receiving said encoded serialized data;

a deserializer for converting said serial encoded data to parallel format;

a decoder for recovering digital data in an error free form; and

interface means for reconstructing data and control signals in said predetermined protocol for transmission to said one or more peripheral device controllers or to said channel.

2. An information handling system according to claim 1 wherein said frame generation means further comprises:

means for controlling transmission of frames of information on said serial data link in one of a plurality of predetermined transmission modes.

3. An information handling system according to claim 2 wherein said control means comprises means for controlling the transmission of frames of information in a double transmission mode without intervening idle characters.

4. An information handling system according to claim 2 wherein said control means comprises means for controlling the transmission of frames of information in a single frame transmission mode with one or more intervening idle characters between frames.

5. An information handling system according to claim 1 wherein said frame generation means further comprises:

means for transmitting control and data signals between said channel and said peripheral device controller in a single frame having a plurality of characters therein.

6. An information handling system according to claim 5 wherein said frame comprises three characters,

a first character including one of a plurality of predetermined start characters,

said start character being selected for error immunity with respect to an idle character,

a second character of said frame including a plurality of control signals, and

a third character of said frame including a plurality of data signals.

7. An information handling system according to claim 1 wherein said interface means for reconstructing comprises:

frame control means for controlling recovery of frame information transmitted in any of said plurality of transmission modes.

8. An information handling system according to claim 7 wherein said frame control means further comprises means for detecting a control frame, wherein said control frame contains signals used to test the .integrity of said serial data link adapter.

9. An information handling system according to claim 1, wherein said interface means for reconstructing further comprises:

frame compare means for comparing a first and second frame transmission transmitted in a double frame transmission mode for testing integrity of transmission.

10. An information handling system according to claim 1, wherein said interface means for reconstructing further comprises:

means for detecting a predetermined error character sequence, and means for transmitting said error character sequence until said error has been eliminated.

11. An information handling system according to claim 1, wherein said serial data link adapter further comprises means for detecting beginning and end of frame transmission.