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Browse Prior Art Database

.Ce MAP Command Improvement

IP.com Disclosure Number: IPCOM000036403D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 4 page(s) / 58K

Publishing Venue

IBM

Related People

Mitchell, GA: AUTHOR

Abstract

This invention relates to a method to reduce the amount of electronic storage necessary to hold a type style in a character encoding algorithm. By reducing the storage required, costs can be reduced.

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 47% of the total text.

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.Ce MAP Command Improvement

This invention relates to a method to reduce the amount of electronic storage necessary to hold a type style in a character encoding algorithm. By reducing the storage required, costs can be reduced.

Conventional character encoding algorithms have the following features: 1. They encode "commands" to a device that is used to print characters. That device could be a printer or typewriter, and these commands instruct it how to create the character to be printed. 2. The characters are divided into vertical columns. The devices using these commands must process one column of a character at a time. For example, the QUIETWRITER* printers and typewriters have only one vertical column of electrodes and they must write the characters on the paper one column at a time. 3. They encode character columns, using commands, from the bottom to the top of the column. 4. The columns are encoded from the left to the right side of the character.

The present method modifies the prior-art way that the columns are encoded by removing data specific to the white space in a column that was encoded by prior-art methods. Using "O" (capital O) as an example, the prior-art method and the present method both store the left and right side, the vertical lines, in a similar manner. The major difference in the methods shows up in the middle, horizontal lines, of the "O". The present method does not store the white area between these lines, as did the prior-art method. The elimination of these "white bytes" is where the storage savings come in.

The character, capital C, shown in the drawing is an actual data pattern that is encoded on a machine by this algorithm. The printable dots, known as pels, are represented by "X's" on the drawing; i.e., where an "X" appears, the pel will be lit. The character is divided into 24 rows and 36 columns. (Some pels, such as row 7-column 31, are not included because of print head and power supply restrictions.)

The improved technique for encoding this character will be used to illustrate the improvement.

The 24 rows are divided into three sets of eight each: the top set (1-8), the middle set (9-16), and the bottom set (17-24). The coding is done one column at a time for each set of eight rows.

Columns 1 through 4 contain no "ON" pels and can be encoded using 1 byte. The most significant 3 bits of the byte would be "101" (all white; repeat column) with the remaining 5 bits indicating the number of blank columns to be repeated.

Thus, the value encoded is (101, and 00100, for 4 blank columns) = 10100100.

Column 5 only has pels on in the middle set. It is encoded using the new map command having the following format:

Map command byte followed by up to 4 data bytes of character data.

1

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The particular Map command byte has the following format: 3 map command bits + 1 extend bit + 4 map bits = map command byte 111 + 0 + (XXXX) map bits = 1110XXXX

The map command bits are always 111.

The extend bit permi...