Recent advances in digital television are exemplified in the techniques now available for processing and correcting the errors that arise when videotape is played back with a VTR. Such techniques use time-base correctors (TBCs) in systems for eliminating VTR distortions. A short history of time-base correction is given, from the delay-line units used 20 years ago with quadruplex VTRs to the latest digital TBCs that can reduce large time-base errors of helical-scan VTRs virtually to invisibility. Principles and details of the Microtime 640 Digital TBC are discussed. Briefly, it operates in either the V/H-lock or no-lock mode. Either direct or heterodyne color recovery can be selected. The input signal is sampled at three times the color subcarrier frequency, and 8-bit PCM encoding is used. For speed and simplicity of control, the Model 640 employs a bipolar random-access memory (RAM) of about 24-kbit capacity. Such TBCs can now interface with virtually any VTR, and their use is expected to grow steadily.