A raster display digital oscilloscope includes an analog to digital converter and a memory array for developing and storing a digital measurement signal amplitude-dependent on an acquired input signal. After processing stored digital signals are conveyed to an output circuit which includes a raster-scanned CRT and three display memory planes independently addressable by the CPU for receiving in discrete address locations the digital data. Corresponding address locations in the three planes are read in synchronism with the CRT scan to develop a display signal for application to the CRT to produce a display corresponding to the sum of the data stored in the three planes. The digital signals are automatically spread out or bunched up within the display planes to compensate for differences between the data acquisition rate and the scan rate.