Abstract: In a machine (10) such as electronic typewriters having a functional package (30) which contain electronic components (31) and (21) respectively, an interlock (13a, 40, 50) inhibits the plugging in and removal of the functional package (30) without removing the plug end (13a) of a line cord (13) from the receptacle (14) on the machine (10). In the receptacle (14) associated with the plug end (13a) of the line cord is the distal end portion (41) of a biased bellcrank (40). The functional package contains a locking bar (50) which extends horizontally of the package (30). Upon insertion of the power cord plug end (13a) into the housed receptacle (14) the bellcrank (40) is caused to rotate engaging the lock bar (50) by passing through an opening (36a) on one side (37a) of the functional package (30).

Abstract: Paper insertion apparatus for indexing a typewriter to a desired first line printing position is triggered using a position detector cooperating with an operator movable paper hold-down bail. When the paper bail is moved to a withdrawn position relative to the paper feed path, the detector produces a signal that causes a logic processor to access, from a dedicated storage location, a code indicating paper advancing increments corresponding to a desired first line printing position. The processor then commands an indexing drive to advance that number of increments. In a preferred implementation, the operator can condition the typewriter to receive a new first line code into storage by means of the keyboard.By so using the presence of the paper bail in a withdrawn position to input the operator's paper insertion request, problems of automatically clearing the path for the leading paper edge are averted and the natural association of the paper bail with paper handling is exploited.

Abstract: An indexing mechanism for a typewriter provides a signal controlled transfer to a fast paper advance rate, say for semi-automatic paper insertion, while storing the last operator-selected rate. Two cams are employed which influence, through a follower, the engagement point of a pawl of a pawl and ratchet platen drive. One cam is operator positionable to change the portion of its cam profile that is tracked by the follower and, attendantly, the paper advance rate. By arranging a signal-controlled actuator to deflect the positionable cam from operative engagement with the follower, the outer cam, which has a less prominent profile, is enabled to influence the pawl engagement point and provides high speed paper advance. Upon removal of the actuator signal the positionable cam is automatically returned to its operative position i.e., the last operator selected position.