Browse Prior Art Database

Mixed Left Right, Right Left Display

IP.com Disclosure Number: IPCOM000048383D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 3 page(s) / 71K

Publishing Venue

IBM

Related People

Warnecke, CG: AUTHOR

Abstract

The display system of the drawings includes storage and logic circuits the operate with data which is meant to flow both right to left and left to right so as to accommodate Middle Eastern and Western language formats. The nub of the approach is to use chained blocks of data in which each block can be read forward or backward.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Mixed Left Right, Right Left Display

The display system of the drawings includes storage and logic circuits the operate with data which is meant to flow both right to left and left to right so as to accommodate Middle Eastern and Western language formats. The nub of the approach is to use chained blocks of data in which each block can be read forward or backward.

The system shown is a raster scanned CRT display with row buffers, but includes concepts applicable to gas panel and other displays. As shown in Fig. 1, a character generator 12 holds patterns for forming dot matrix character images on CRT display screen 13. A display control module 15 provides coded characters which address generator 12 in the sequence in which character images are to be displayed. As the pattern for a horizontal slice of a character is read from the character generator and entered on a multi-bit bus 19, it is loaded into a shift register 20 to form a serial video signal on a line 21.

The display control module 15 executes a command list 22 in system memory 23 and fetches coded characters (in an order defined by the contents of the command list 22) from a refresh buffer 14. These addresses are stored in one of the display control module's row buffers 16. At the same time, data from the other row buffer 17 is being read via a multi-bit bus 8 end used to access the character generator 12 for display refresh. Each character in the row buffer being used for display refresh is read once for each scan line of every character row. At the end of every character row, the respective roles of the row buffers 16 and 17 are reversed for the next character row.

The display control module 15 is capable of executing a number of different commands. The first command is FETCH BLOCK, which directs the display control module 15 to fetch characters from the refresh buffer in either of two modes, called ascending order (F.B.A.) end descending order (F.B.D.), and to place those character addresses in the row buffers 16 and 17, as described above. The ascending order mode is used for left to right data, and the descending order mode is need for right to left data. This command has two parameters associated wit...