Browse Prior Art Database

Proportional and Fixed Pitch Character Display

IP.com Disclosure Number: IPCOM000048381D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 3 page(s) / 43K

Publishing Venue

IBM

Related People

Stockwell, DA: AUTHOR

Abstract

An earlier article (*) describes a method of detecting the completion o the display of variable width characteristics. The method involves bounding one side of the character with O's in the pel matrix of the character as stored in the character generator of the display. The method described below is a variant whereby the character as stored in the character generator is centered in its character box or matrix and is bounded on both sides with 0's, and with 1's in the remaining border pel positions, if any. This allows decoding for either fixed pitch proportionally spaced display.

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Proportional and Fixed Pitch Character Display

An earlier article (*) describes a method of detecting the completion o the display of variable width characteristics. The method involves bounding one side of the character with O's in the pel matrix of the character as stored in the character generator of the display. The method described below is a variant whereby the character as stored in the character generator is centered in its character box or matrix and is bounded on both sides with 0's, and with 1's in the remaining border pel positions, if any. This allows decoding for either fixed pitch proportionally spaced display.

In the table below, the letters "I" and "T" are shown as examples. Since "I" is a narrow letter, it will take up less than a full character width when displayed in proportional spacing mode. Thus, in the case of a "I", 1 bits are provided in the character generator on both sides of the character, to serve as proportional spacing flags. In no case are these flag bits displayed. When the system is operating in proportional mode, the 1's on the left border are used as controls to, in effect, left adjust the character in the display. Those at the right border are employed to indicate completion of the display of the character, as described below: 1 1 0 1 1 1 0 1 1 0 1 1 1 1 1 1 1 0 1 1 0 0 1 0 0 1 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 0 1 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 0 1 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 0 1 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 0 1 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 0 1 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 0 1 1 0 0 0 0 1 0 0 0 0 1 1 0 1 1 1 0 1 1 0 0 0 0 1 0 0 0 0

The video serializer 14 in the figure on the next page is parallel loaded from the character generator 16 with an N-bit pattern representing one horizontal slice of a character. The top slice of an "I" is shown. The control logic 18 examines the leading bits (starting from bit N) to determine the first bit containing a 0. Control logic 18 will set an internal latch (not shown) indicating that the video data stream will be ta...