Text processing apparatus with two-stage formatting of text

Abstract

Text editing and subsequent reformatting of a document is performed in two separate stages run as two parallel processes with different priorities. The editing of text is performed as a high priority process directly on a selected portion of the document previously copied under control of edit/format control logic 7 from a document store 5 into a refresh buffer 3. The editing process takes each keystroke as it is received by control logic 7 from keyboard 8 and enters it into buffer 3. The contents of the buffer 3 are directly mapped onto a display screen 2 so that the updated portion of the document is immediately seen by the operator. Should insufficient space be available in buffer 3 to accommodate an edited line of text, space is made available by controlled wordspill of text from the line into auxiliary storage prior to execution of the editing operation. Reformatting of the edited text is conducted as a low priority process taking one line of the document at a time and any words in auxiliary store for inclusion in that line. Reformatting is interrupted by the occurrence of keystroke signals requiring further editing of the text.