| 摘要 |
1,175,988. Selective signalling. INTERNATIONAL BUSINESS MACHINES CORP. 1 July, 1968 [17 July, 1967], No. 31423/68. Heading G4H. In a keyboard controlled typewriter a record of the position of a printing head with respect to the paper is up-dated in two ways: (1) as the printing head is letter-spaced forwards or backwards along a line a horizontal position word is repeatedly augmented or decremented by unity, the word being reset to zero whenever a cariage return signal occurs, and (2) when the printing head is tabulated to a new position, the horizontal position word is compared in turn with an ascending sequence of pre-stored words representing the positions of those tab stops that have been set, until the first one which is greater than the horizontal position word is found, whereupon this tab stop word is taken as the new horizontal position word. Tab stop words are also available from store in reverse order so that backward tabulation is possible. |
