a wealth of convenience features. Measurement enhancements available include: Auto-ranging, which selects the correct range for the quantity under test so that the most significant digits are shown. For example, a four-digit multimeter would automatically select an appropriate range to display 12.34 mV instead of 0.012 V, or overloading. Auto-ranging meters usually include a facility to hold the meter to a particular range, because a measurement that causes frequent range changes can be distracting to the user. Auto-polarity for direct-current readings, shows if the electric polarity of applied voltage is positive (agrees with meter lead labels) or negative (opposite polarity to meter leads). Sample and hold, which will latch the most recent reading for examination after the instrument is removed from the circuit under test. Current-limited tests for voltage drop across semi conductor junctions. While not a replacement for a proper transistor tester, and most certainly not for a swept curve tracer type, this facilitates testing diodes and a variety of transistor types. A graphic representation of the quantity under test, as a bar graph. This makes go/no-go testing easy, and also allows spotting of fast-moving trends. A low-bandwidth oscilloscope. Automotive circuit testers, including tests for automotive timing and dwell signals (dwell and engine rpm testing is usually available as an option and is not included in the basic automotive DMMs). Simple data acquisition features to record maximum and minimum readings over a given period, or to take a number of samples at fixed intervals. Integration with tweezers for surface-mount technology. A combined LCR meter for small-size SMD and through-hole components. Modern meters may be interfaced with a personal computer by IrDA links, RS-232 connections, USB, or an instrument bus such as IEEE-488. The interface allows the computer to record measurements as they are made. Some DMMs can store measurements and upload them to a computer. The first digital multimeter was manufactured in 1955 by Non Linear Systems. It is claimed that the first handheld digital multimeter was developed by Frank Bishop of Intron Electronics in 1977, which at the time presented a major breakthrough for servicing and fault finding in the field. Analog multimeters A multimeter may be implemented with a galvanometer meter movement, or less often with a bargraph or simulated pointer such as a liquid-crystal display (LCD) or vacuum fluorescent display. Analog multimeters were common; a quality analog instrument would cost about the same as a DMM.