Abstract: A technique for providing automatic modification of a computer application program adopts the program for compatibility with hardware different from that for which the program was originally written and tested. Upon initial loading of the application program, a search is made to determine the existence of a set of exception tables, external to the application program. If the exception tables are present, all code conversion tables within the application program relating to I/O operations are modified according to the set of exception tables. Plural sets of exception tables may be included with the ability of the operator to choose which set of exception tables will be used to modify the program, thereby allowing the operator to use a single program with a variety of different hardwawre configurations, assuring with each configuration that the intended characters and symbols are displayed and printed.

Abstract: Operator keystrokes are processed in a text processor system to put characters and symbols on a fixed pitch display screen without limitation as to other size characters or symbols on the screen. Keystroke data is processed under the control of programs stored in a random access memory. For a mixed pitch display, the random access memory of the system is structured to include a text storage buffer and a display control block both interconnected to an applications program and a display access method program. Data is stored in the text storage buffer in an unformatted configuration in a mixed pitch arrangement and the programs evaluate the data to display characters and symbols with correct character pitch. The programs also draw a scale line on the screen to provide character information to the operator.

Abstract: A ghost cursor indicates the relative horizontal position on a display screen associated with a printed document rendition of the displayed text and control codes. In a normal, or hidden codes, mode of operation the ghost cursor, placed on an escapement scale line, is vertically aligned with a text cursor which is positioned adjacent the displayed text code which defines the present point of operation. In the all codes mode, all text and control codes (such as required backspaces, tabs, etc.) are displayed. In the all codes mode the ghost cursor indicates the relative horizontal position on the display screen of the code associated with the text cursor, with forward or reverse escapement indicated by the control codes taken into account.