公开(公告)号：CA2095054A1

公开(公告)日：1993-12-21

申请号：CA2095054

申请日：1993-04-28

Applicant: IBM

Inventor： JUDD IAN D ,  BEER REGINALD

IPC: H04L1/00 ,  H04L1/18 ,  H04L12/28 ,  H04L69/40 ,  H04L29/14

Abstract: An error recovery method for use in an information communication system which comprises a plurality of nodes connected by links. Information is transferred between the nodes in frames of predefined types, including at least a first frame type used to transfer data and a second frame type used for error recovery. Each node has at least a first and a second mode of operation, in the first mode frames of both first and second types are accepted, in the second mode frames of the first type are discarded and only frames of the second type are accepted. A master node which controls error recovery is selected from amongst those nodes which can initiate transfers.

公开(公告)号：CA1089991A

公开(公告)日：1980-11-18

申请号：CA290044

申请日：1977-11-02

Applicant: IBM

Inventor： JUDD IAN D ,  MINSHULL JOHN F

IPC: G06F3/12 ,  G06K9/54 ,  G06T3/00 ,  G06T9/20 ,  G09G5/24 ,  G06K7/00

Abstract: An image encoding apparatus and technique in which raster scanned data is processed so that the characters represented thereby are thinned into a series of strokes. These strokes represent the shape of the characters, either their centre lines or their outlines. The modified bit pattern representing these strokes is then processed in a line follower which detects contiguous bits and determines whether contiguous bits conform to a predetermined constraint. A series of segments are produced representing the tracked strokes. Each segment is coded by shape and the position of its end point. The image is thus encoded as a series of segments in a segment list.

公开(公告)号：FR2374780A1

公开(公告)日：1978-07-13

申请号：FR7734670

申请日：1977-11-10

Applicant: IBM

Inventor： EVANS JOHN M ,  LOVIE RICHARD H ,  JUDD IAN D ,  MINSHULL JOHN F

IPC: H04N5/262 ,  G06K9/54 ,  G06T3/00 ,  G06T9/20 ,  G06T11/20 ,  G09G5/36 ,  H04N1/411 ,  H03K13/24 ,  G06K9/00

Abstract: Graphical data on a document is raster scanned and the resulting bit pattern is processed to provide a processed bit pattern which represents lines which each are a single pel in width and indicative of the shapes of objects scanned on the document. These single pel wide lines may represent the outlines of objects on the center lines. The processed bit pattern is then directed to a line follower in which bits representing contiguous pels are detected and tested for linearity. When contiguous pels fail the linearity test, a new vector is started and the vector being tracked is terminated. Hardware for performing these operations is described. The resulting vector list is stored until needed for display. Optionally a display station can be used to correct faulty vectors or to encode alphanumeric data in a more convenient format than vector coding.

公开(公告)号：GB2252020A

公开(公告)日：1992-07-22

申请号：GB9026336

申请日：1990-12-04

Applicant: IBM

Inventor： SHAH VINAY VELJI ,  JUDD IAN D ,  BEER REGINALD

IPC: H04L1/18 ,  H04L1/16 ,  H04L29/06 ,  H04L29/08

Abstract: Described is a system and method of communicating between first and second nodes connected by a serial link wherein the data is transmitted between the nodes in the form of packets made up of multiple bit frames. Each packet that is correctly received by the second node is acknowledged by means of a pair of multibit frames. These frames may be interleaved among the frames making up any outgoing data packet that is being transmitted by the second node. The technique employed provides unambiguous acknowledgment of each data packet and if a data packet is received incorrectly, the packet is available in a buffer in the first node for resending.

公开(公告)号：GB2250897A

公开(公告)日：1992-06-17

申请号：GB9026338

申请日：1990-12-04

Applicant: IBM

Inventor： SHAH VINAY VELJI ,  JUDD IAN D ,  GRAINGER BERNARD JOHN ,  COCKBURN GORDON JOHN

IPC: H04L1/16 ,  H04L1/18

Abstract: Described is a method of error recovery in a data communication system of the kind comprising two nodes connected by a serial link and wherein data is transmitted between the nodes in the form of packets of a predefined format. Each node receives data over an inbound line and transmits data over an outbound line. When an error is detected, both notes enter a link check state, invoke a Link Error Recovery Procedure (ERP) and exchange status by means of Link Resets. Error recovery is performed separately for each line. Each node is responsible for recovering packets that were lost on its outbound line. In normal operation of the link, the transmitter does not reuse a packet buffer until it has received a response from the connected node indicating that the packet was correctly received. Therefore, when an error occurs, the affected packets are still available for retransmission.

公开(公告)号：CA1160352A

公开(公告)日：1984-01-10

申请号：CA364796

申请日：1980-11-17

Applicant: IBM

Inventor： JUDD IAN D

IPC: H04N3/23 ,  H04N3/26 ,  H04N9/28 ,  H04N17/04 ,  H04N3/22 ,  H01J29/56

Abstract: EQUIPMENT TO CORRECT ABERRATIONS OF A CATHODE-RAY BEAM Aberrations of an electron beam are corrected as the beam is scanned across the screen of a cathode-ray tube by deriving correction signals from stored digital values by means of the calculus of finite differences. The digital values, which are the initial differences of polynomial correction functions, are held in store 10 and summed in adder 20, the results being converted by digital-to-analogue converter 50 to analogue signals and supplied to the cathoderay tube. Provision is made for the reduction of error in the calculations by shifting higher order differences relative to lower order differences before addition. The circuitry may be implemented on a single chip. Preferably the inventtion is applied to the correction of misconvergence in a shadow mask tube. UK9-79-004