The Tektronix CG551AP is a Programmable Calibration Generator that is a microprocessor based oscilloscope calibration generator that is fully programmable. It can be used as part of a computerized system for the calibration and verification of major oscilloscope parameters, including vertical gain, horizontal timing and gain, vertical bandwidth/pulse characteristics, probe accuracy and compensation, current probe accuracy and calibrator output accuracy. Many of the calibration and test steps previously performed by the operator can now be transferred to the computer which executes them in a consistent and error-free manner. The CG551AP is a TM 500 version of the CG 5001 and requires a TM 506 Mod JB, TM 515 Mod UB or RTM 506 Mod JB (sold separately).