The DC 505 Universal Counter/Timer has seven measurement functions: frequency counting, finding frequency ratios, period timing, interval timing, width timing, electronic event counting, and manual event counting. The DC 505 has two input channels (A & B), each having bnc inputs and separate triggering level, attenuators, and coupling mode controls. Both input channels have the same 225 MHz capability. Seven-segment light-emitting diode arrays (しED.s) provide a seven-digit visual numerical display. The decimal point is automatically positioned and the leading zeros (to the left of the most significant digit or decimal point) are blanked. Digit overflow is indicated by a flashing display. Signals to be counted/timed can be applied to either or both channel A or channel B front-panel bnc connector or to the rear interface connector. The DC 505 is designed to operate in a TM 500-Series Power Module. The DC 505 can be ordered equipped with a temperature-compensated, 5 MHz crystal oscillator to obtain a highly stable and precise internal time base. This option includes a divide-by-five IC counter to produce the 1 MHz clock.