Browse Prior Art Database

Tab Expansion In Line Memory of Typewriter

IP.com Disclosure Number: IPCOM000084287D
Original Publication Date: 1975-Oct-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

McCray, WR: AUTHOR

Abstract

A typewriter incorporating a line storage unit for recording keg strokes, in order to effect subsequent playout, includes a decode unit which generates fill codes to be stored in the line storage unit to facilitate tabulation and backspacing operations.

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Tab Expansion In Line Memory of Typewriter

A typewriter incorporating a line storage unit for recording keg strokes, in order to effect subsequent playout, includes a decode unit which generates fill codes to be stored in the line storage unit to facilitate tabulation and backspacing operations.

Typewriter 11 includes a conventional keyboard, the mechanical key strokes of which are converted by converter 13 into electrical signals which are stored in line storage unit 15. Operator depression of tab key 17 effects relative motion between the print mechanism and the paper carriage until a mechanical tab stop is encountered. Decode unit 19 is responsive to the relative motion to generate a series of fill codes to be stored sequentially in the line storage unit 15. For example, a tab of 123 units on a 10-pitch machine would be expanded into a three-unit fill code, 24 five-unit fill codes, and a tab code.

When a backspace operation is initiated, the last character stored is read from the line storage 15 to effect a backspace operation equal to the number of escapement units of the last character stored. When a backspace operation encounters a tab code, the backspace is repeated and the relative motion effected corresponds to that of the last fill code. Thus, in the example a backspace after a tab will cause relative motion of five units.

Upon completion of entering characters for a typewritten line, the information in line storage 15 is transferred to the page storage...