A computer-controlled cardiotachometer

A versatile display system for presenting heart rate information is described. The display has a table with 10 rows and 50 columns. This 10 by 50 matrix contains all integers from 0 to 499, so that it can display the instantaneous R-R intervals of a rat’s EKG to the nearest millisecond. At each beat 1 of 10 vertically and 1 of 50 horizontally arranged indicator lights are turned on to provide the coordinates for reading the table. Either beat-to-beat or averaged heart rate or period is displayed. Small and large changes can be easily and accurately observed on the same scale. The lights are controlled by a PDP-8/e. A listing of the assembler program is presented.