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Page Indexing System for Code Translation

IP.com Disclosure Number: IPCOM000073690D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Yeung, DD: AUTHOR [+2]

Abstract

The page-indexing system presented addresses the problem of converting a (1 x p) code into a (n x m) code. Since a (1 x p) code can uniquely define 2p of the (n x m) code (called a character), 2p of the characters are arranged in tables called dictionaries. Data to be translated (1 x p codes) is called a data stream, and should be preceded by text defining the dictionary to be used.

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Page Indexing System for Code Translation

The page-indexing system presented addresses the problem of converting a (1 x p) code into a (n x m) code. Since a (1 x p) code can uniquely define 2p of the (n x m) code (called a character), 2p of the characters are arranged in tables called dictionaries. Data to be translated (1 x p codes) is called a data stream, and should be preceded by text defining the dictionary to be used.

The translation can be performed very fast by table look-up methods if all dictionaries are stored in the main memory. The (1 x p) code serves as address pointer for the look-up process. The disadvantage of this approach is that it requires a large amount of main storage. The page indexing scheme, conversely, minimizes the amount of main storage required without sacrificing speed of translation.

In the page-indexing system, all the dictionaries are stored on the disk, and a small area of main storage is used as work area for translation. The dictionaries are divided into pages. The first page of the dictionary is called the index page. The index page is an index of the dictionary and gives the address (page of the dictionary and location on the page) of every character in it. The index page resides on the disk at the dictionary address defined by the text preceding the data stream. When the data stream addresses a dictionary, the index page is read into the reserved section of main storage. Each (1 x p) code in the data stream points to a sect...