18. A text-editing and display system for displaying lines of characters, said system comprising: A. a processor for performing editing operations in response to editing commands; B. a memory unit connected for data transfer with said processor for storing character codes defining characters to be displayed and word delimiters, at least some of which are also characters, said processor performing editing operations on the character codes stored in said memory, the character codes corresponding to successively displayed characters being stored in said memory unit for retrieval in sequence, and C. a display unit comprising: i. a display device for displaying frames of text formed of lines of displayed characters in a predetermined timing sequence, and ii. a display controller connecting said memory unit and said display device, said display controller including: a. timing means connected to said display device for establishing the predetermined timing sequence, b. running-address register means connected to said memory means and said timing means for addressing said memory unit to retrieve the character codes therefrom in sequence, c. a character register means connected to said memory unit and said timing means for receiving and holding the succession of character codes retrieved from said memory unit, d. display causing means connected to said character register and to said display unit and responsive to the contents of said character register for causing the display of a corresponding line of successive characters at said display device, e. a margin register connected to said processor for storing a number indicating a selected maximum line length and thereby defining a line-ending margin position, f. position recording means connected to said timing means for recording the position, along said line, of the last word delimiter to be displayed in the line of characters, g. inhibiting means connected to said position recording means and said display causing means and responsive to the recorded position along said line of the last word delimiter for inhibiting the display of the characters that succeed the last word delimiter, and h. means connected to said timing means and said running address generator means and operable after the beginning of each display frame for setting said running-address register means to the memory address of the next character code for use in the retrieval of character codes for the next line of characters to be displayed.
18. A text-editing and display system for displaying lines of characters, said system comprising: A. a processor for performing editing operations in response to editing commands; B. a memory unit connected for data transfer with said processor for storing character codes defining characters to be displayed and word delimiters, at least some of which are also characters, said processor performing editing operations on the character codes stored in said memory, the character codes corresponding to successively displayed characters being stored in said memory unit for retrieval in sequence, and C. a display unit comprising: i. a display device for displaying frames of text formed of lines of displayed characters in a predetermined timing sequence, and ii. a display controller connecting said memory unit and said display device, said display controller including: a. timing means connected to said display device for establishing the predetermined timing sequence, b. running-address register means connected to said memory means and said timing means for addressing said memory unit to retrieve the character codes therefrom in sequence, c. a character register means connected to said memory unit and said timing means for receiving and holding the succession of character codes retrieved from said memory unit, d. display causing means connected to said character register and to said display unit and responsive to the contents of said character register for causing the display of a corresponding line of successive characters at said display device, e. a margin register connected to said processor for storing a number indicating a selected maximum line length and thereby defining a line-ending margin position, f. position recording means connected to said timing means for recording the position, along said line, of the last word delimiter to be displayed in the line of characters, g. inhibiting means connected to said position recording means and said display causing means and responsive to the recorded position along said line of the last word delimiter for inhibiting the display of the characters that succeed the last word delimiter, and h. means connected to said timing means and said running address generator means and operable after the beginning of each display frame for setting said running-address register means to the memory address of the next character code for use in the retrieval of character codes for the next line of characters to be displayed. 22. A text-editing and display system as defined in claim 18 in which said controller additionally includes: j. a first-text-address register connected to and settable by said processor, and k. means connected to said first-text-address register and said running address register means for loading the contents of said first-text-address register into said running address register means prior to the beginning of each display frame, whereby said display device repeatedly displays a string of characters beginning with the characters corresponding to the character codes stored in said memory unit at the address indicated by said first-text-address register.