Abstract: A frequency shift key modulator producing sine wave output signals of different frequencies for mark (1) and space (0) signal levels on an input "send data" lead including a counter which divides the frequency of an input oscillator by different denominators for the mark and space signals and the output of which is synthesized to produce a stepped output approximating a sine wave and a final filter for smoothing the steps out of the output. In cases in which the mark and space output frequencies are approximately in the ratio of 1 to 2, a frequency divider is used for the mark output frequencies.

Abstract: A machine for holding a tape cartridge and including propelling means for driving the tape through the cartridge in both directions. The machine has a cartridge receiving slot with a drive roll at the bottom of the slot disposed on a rotatable drive member carried by a swingable member. A pair of drive rolls are driven from an electric motor and are disposed with respect to the swingable member so that, when the swingable member is swung in opposite directions, the drive rolls drive the rotatable drive member in opposite directions for thereby driving the tape in opposite directions. A pair of swing arms are on opposite sides of and are both effective on the rotatable drive member in a neutral position of the swingable member for braking the drive roll at the bottom of the slot. The swing arms are moved out of braking engagement with the rotatable drive member when the swingable member is moved to bring the rotatable drive member into driven relationship with respect to said pair of drive rolls.