International Business Machines Corporation

Kapali P Eswaran

Tien C Chen

Chin Tung

Vincent Yu-Sun Lum

Robert C Durbeck

Vincent C Hamacher

Gerald St Shedler

Apparatus and method for enabling asynchronous, collision-free communication between ports on a local shared bus network which is efficient in the use of bus bandwidth and which, in one embodiment, provides a bounded, guaranteed time to transmission for each port.

Port logic for a communication bus system

Composer method and apparatus are disclosed in which human readable representations of characters are typed on the first part of a page and are thereafter typed on a second part of the page in the machine readable form. Key stroke signals generated by the typewriter keyboard are stored in a memory prior to being applied to access corresponding type ball positioning signals within a table to print the characters using a conventional type ball on the first portion of the page. Thereafter, the conventional type ball is replaced by a special type ball and the key stroke signals stored in the memory are used to access corresponding ones of a different set of type ball positioning signals within a second memory to enable the special type ball to type optically readable binary coded representations of the characters on the second part of the page. Each character is represented by a string of seven bits plus a parity bit which are typed using either a single strike of a group of eight bits on the special type ball or two different strikes using two different groups of four bits on the special type ball.

Method and apparatus for typing characters and optically readable binary

An apparatus for sorting of equal length records with the sorting time maximally overlapped by the time taken for loading and unloading of records. The minimal structure consists of a decision mechanism linked to and associated with a network of ladder structures. The activity within the network is so synchronized that the sorting activity in most ladders occurs while some ladder within the network is still undergoing the loading of input data; and during the unloading phase, the individually sorted data from each ladder are merged concurrently to produce a sequence of sorted records. The overlap between sorting and loading varies from 0 for records requiring no loading/unloading, to 100% for multi-ladder networks with loading/unloading. A single ladder structure supporting a type of transposition sort is first described both in a full exchange scheme and a fast version. Then, the mechanism for loading/unloading equal length records to the single ladder is set forth. Next, the use of two ladders of dissimilar lengths for facilitating the overlap between loading/unloading and sorting is revealed. Lastly, the general multi-ladder case with which complete overlap is achieved terminates the specification. The ladders themselves are formed from a plurality of equal length loops connected by dual mode switches such that when a switch between a pair of adjacent loops is set electrically into the first mode ('on') the adjacent loops are cross-connected facilitating an exchange of any records circulating therein. When the two switches bounding a loop are electrically set in the second mode ('off'), the loop is maintained as a circulating path. An end loop of each ladder operates as an input/output port. In one embodiment, control signals for operating the dual-mode switches are developed by an external decision mechanism through the expedient of storing and comparing the keys of each record to be sorted, said signals control the switches in loading, sorting, merging and extracting. An alternate embodiment can employ a plurality of detectors to transmit the detected keys to a decision mechanism dynamically without previously copying the keys.

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San Jose, CA, United States of America

Kapali P Eswaran