A multimeter is the combination of a DC voltmeter, AC voltmeter, ammeter, and ohmmeter. Some instruments combine the functions of a digital multimeter with the oscilloscope. Every inline series-connected ammeter, including a multimeter in a current range, has a certain resistance. A typical multimeter can measure voltage, current, and resistance. A Wheatstone bridge and a multimeter both include voltage dividers. The sensitivity of an analog multimeter is given in units of ohms per volt. The fluctuations in voltage and current can be logged with a multimeter or data logger. This will mask the gate's supposed diode-type behaviour when testing a TRIAC with a multimeter. A digital multimeter displays the quantity measured as a number, which eliminates parallax errors. A digital multimeter samples the quantity being measured over time, and then displays it. The first digital multimeter was manufactured in 1955 by Non Linear Systems. In 1974, Radionics launched the DM1 digital multimeter. Often the display count is just called the 'count' in multimeter specifications.