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Error Correction for Performing Spacing Typewriter

IP.com Disclosure Number: IPCOM000091065D
Original Publication Date: 1969-Oct-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Johnson, CF: AUTHOR [+4]

Abstract

A proportional spacing typewriter consists of a proportional spacing printer, a keyboard, a recording media and an error control device. Keying errors are corrected by backspacing the printer and recording media and inserting the correct character. Since each character is assigned a predetermined escapement value, the recording media must be read prior to backspacing the printer to determine the amount of reverse printer escapement. If the recording media cannot be correctly read, the backspace operation is nevertheless performed and a predefined escapement is substituted for the escapement of the unreadable but previously printer character.

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Error Correction for Performing Spacing Typewriter

A proportional spacing typewriter consists of a proportional spacing printer, a keyboard, a recording media and an error control device. Keying errors are corrected by backspacing the printer and recording media and inserting the correct character. Since each character is assigned a predetermined escapement value, the recording media must be read prior to backspacing the printer to determine the amount of reverse printer escapement. If the recording media cannot be correctly read, the backspace operation is nevertheless performed and a predefined escapement is substituted for the escapement of the unreadable but previously printer character.

An error correct backspace operation is initiated by depressing a backspace key on keyboard 11 which effects entry of a backspace character in character register 13, decoding of the character by decode 15, and setting of backspace latch 17. The latter actuates drive control 19 to move recording media 21 in the reverse direction so that read head 23 reads character N when the media is later moved in the forward direction. As character N is sensed, it is temporarily stored in read register 25 and checked for error. First error latch 27 is set upon error detection. Otherwise, character N is transferred to register 13, decoded by decode 15 and gated through And 29 to control the reverse escapement of the printer. Media 21 is simultaneously moved in the reverse direction so that t...