Apparatus for printing alpha-numeric characters for plotting an incoming signal at rates on the order of one page every seven seconds for rapidly verifying that the system producing the incoming signal is operating properly. Both printing and plotting are done by styli mounted on a moving carriage and individually electrified to produce marks on a specially prepared paper. The stylii are moved back and forth across the paper, marking in both directions. The carriage is not stepped across the page, but instead is moved smoothly from one side to the other side under control of a velocity servo. A controller generates and applies velocity command inputs to the servo, based on the position of the carriage as sensed by an optical encoder, and based on certain characteristics of the incoming signal. A first buffer memory accumulates the incoming signal until a line has been stored for plotting, while a second buffer memory is applying its accumulated contents to the printhead. Thereafter, the first memory supplies the printhead while the second memory accumulates. The apparatus includes a versatile formatting system which determines the amount of data to be plotted in each line in accordance with the incoming timing signals associated with the data. If the timing signals are not present, the apparatus makes the determination autonomously.
Validator for electrocardial data processing system