This disclosure relates to a comprehensive method of codifying the different encoding schemes that are used for graphic character representation, resulting in a single identification mechanism that is used in conjunction with a corresponding registry to simply and uniquely identify the scheme used. The mechanism comprises such a short form identifier having the capability of acting as a short form (alias) for its corresponding list of component identifiers; acting as a short form for a collection of specific component identifiers having a specific property; allowing special meanings to be conveyed in relation to tagging of data with the code identification; and allowing bridging to existing systems that use only some components of the code identification.

A first system sends a message to a second system via a modem. A processor in the first system, in conjunction with a stored encoding algorithm, encodes the characters of the message by locating unacceptable characters (U) among the acceptable characters (A) in the message, the unacceptable characters possessing more than one meaning and triggering the execution of a function other than the intended function. A bias code (70) is selected for the acceptable characters (A) and a further bias code (75) is selected for the unacceptable characters (U). The unacceptable characters are converted into modified acceptable characters (Aʹ). The bias code, acceptable characters, further bias code, and modified acceptable characters are then transmitted. The second system interprets the bias code to mean that the acceptable characters should be accepted without alteration, but interprets the further bias code to mean that the modified acceptable characters should be re-converted into the original unacceptable characters.

Appareil programmable de transcodage (AT) dans lequel des suites de mots binaires de longueurs variables correspondant à des chaînes de caractères dans un premier alphabet sont transcodés en d'autres suites de mots binaires intelligibles dans un second alphabet. L'appareil est relié à des systèmes numériques (S1, S2) échangeant des suites de mots par des interfaces (1, 2) munies de files d'attente (12, 22). Une unité centrale (4) connectée aux interfaces à travers un dispositif d'aiguillage (5) reçoit les suites entrantes et délivre des suites de mots binaires transcodés/ Une unité de gestion d'échange (3) assure le contrôle des transferts de données dans l'appareil ainsi que la régulation des débits de mots entre l'appareil et les systèmes numériques. Un terminal ou un micro-ordinateur peut également équiper l'appareil pour l'élaboration de tables de transcodage à télécharger dans une mémoire vive (43) de l'unité centrale.

A terminal which is capable of receiving, converting and displaying both NAPLPS and PRESTEL coded signals and which includes means for invoking NAPLPS control and character codes, corresponding to the same, received PRESTEL codes, to an in-use table from NAPLPS code look-up tables at the terminal and for separately processing, decoding and converting PRESTEL attribute codes to produce corresponding NAPLPS codes.

This invention relates to a protocol converting apparatus in which when character information electronic signals of a NAPLPS (North American Presentation Level Protocol Syntax) system are displayed on a user terminal apparatus of a CAPTAIN - (Character And Pattern Telephone Access Information electronic signal Network) system, the overflow condition in a row direction and the overflow condition in a column direction are detected and in which in the case of the overflow condition in a column, an overflow character information electronic signal is temporarily stored in a memory, whereby the NAPLPS character information electronic signal can be used by all user terminals of the CAPTAIN system.