The TDS640 Oscilloscope is a 500MHz, 4 channel digitizing oscilloscope. The sample rate is 2GHz. The display features infinite and variable persistence selectable from 250 ms to 10 s. The update rate is 100 waveforms per second (500 point waveforms with infinite persistance display selected). Other features include zoom, Main and Delayed time base. Trigger types include Edge (main and delayed), Pulse (main) and Logic (main).