Abstract: A mechanism to limit the starting and stopping movement of a print head in a printing operation comprising moving a plurality of character representing signals in memory from a source to the printing operation at a rate in excess of the rate at which characters are normally available from the source such that a substantial number of characters are printed along a line on a record medium before the memory storing the character signals is empty of the initially stored character signals and the additional character signals received during the printing operation. Overrides are provided depending on the frequency of data received from the source and the appearance of a control code in memory.

Abstract: The potential errors introduced by contact bounce are eliminated by a system which accepts applied key data. The system will accept key data provided first, that it is a proper logic code; second, that the system is in a state to accept new data; and, finally, that it is either different than the previous acceptable logic code or that it is preceded by a no key period measurably exceeding the contact bounce time and shorter than the normal human response time of the typist.