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Code Translation Algorithm

IP.com Disclosure Number: IPCOM000086822D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Gaudet, JL: AUTHOR [+2]

Abstract

Translation of a system internal code set corresponding to a particular keyboard into or out of a chosen communications line code set is accomplished in accordance with a keyboard identification number corresponding to the internal code set in use. An efficient technique is utilized for reducing the amount of storage needed for storing tables for accomplishing the task when a large number of keyboards and another large number of communications line code sets are to be paired.

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Code Translation Algorithm

Translation of a system internal code set corresponding to a particular keyboard into or out of a chosen communications line code set is accomplished in accordance with a keyboard identification number corresponding to the internal code set in use. An efficient technique is utilized for reducing the amount of storage needed for storing tables for accomplishing the task when a large number of keyboards and another large number of communications line code sets are to be paired.

Assume that M system internal code sets may be utilized by a system that can accommodate M keyboard code configurations. Certain ones of the alphanumerics and symbols of the keyboard, referred to as common codes, are common to each of the keyboard options of any language. Additional codes not included in every keyboard are referred to as special graphics codes. Assume that with N communications line code sets, it is desirable to translate each of the M internal code sets into or out of a preselected one of the N communications line code sets according to the following criteria:
(1) A given alphanumeric or symbol on a given keyboard, when

struck, will ultimately produce in the preselected

communications line code set, the binary code for that symbol

if it exists for that preselected communications line code

set; and
(2) Special graphics codes that exist in one code set but do not

exist in the other code set are paired together, as

substitutes, for operator convenience.

For translation from a particular system internal code set, identified by a keyboard number, to a preselected communications line code set, the internal code to be transmitted accesses a single byte of a first table according to the bit pattern of the code to be translated. If the code is one of the common codes, the code stored at the accessed point in the table is transferred to the communications link as the appropriate code of the particular communications line code set. If, upon accessing the table, a bit pattern is read therefrom that indicates that the code to be transmitted is one of the special graphics codes, a byte of a second table is accessed according to the bit pattern of the code to be translated.

The accessed byte of the second table contains a displacement value that is added to the initial address of a third transmit table corresponding to the keyboard number of the system...