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Underscoring Display Attachment

IP.com Disclosure Number: IPCOM000075616D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Boyd, WW: AUTHOR

Abstract

In certain magnetic media products such as the IBM Magnetic Card "SELECTRIC" Typewriter, the word underscore code follows the word to be underscored, as illustrated in Fig. 1. This obviously presents a problem when the data is to be displayed, since the word is already in the video buffer before the word underscore code is detected.

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Underscoring Display Attachment

In certain magnetic media products such as the IBM Magnetic Card "SELECTRIC" Typewriter, the word underscore code follows the word to be underscored, as illustrated in Fig. 1. This obviously presents a problem when the data is to be displayed, since the word is already in the video buffer before the word underscore code is detected.

Fig. 2 represents a technique for accomplishing word underscore with the format of Fig. 1 in a display. When a word underscore code is decoded in buffer A, the eight bit will be turned on in the character in buffer B. The next shift pulse will shift the contents of buffer B into the video buffer, and the word underscore code will be discarded. As output commences from the video buffer, the last character of the word will be underscored on the first frame of display after the word underscore has been detected.

The logic controlling the video buffers will also turn on the eight bit of a character, if the preceding character has its eight bit set. During horizontal retrace those video buffers not being loaded will be shifted around to their starting point. As the characters are being readied for display, the eight bit is turned on if required. This process continues until a space is the next character to have the eight bit set, at which time the process terminates. Thus underscoring a word will take as many frames of display as there are characters in the word.

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