of signals. Early solutions attempted to combine hardware from multiple oscilloscopes into one package, but screen clutter, a lack of definite data interpretation, as well as probing constraints made this solution only marginally usable. The HP 5000A Logic Analyzer, introduced in the October 1973 issue of the Hewlett-Packard Journal, was probably the first commercially available instrument to be called a "Logic Analyzer". However, the HP 5000A was limited to two channels and presented information by means of two rows of 32 LEDs. The first truly parallel instrument was the twelve channel HP 1601L, it was a plug-in for the HP 180 series oscilloscope mainframes and used the oscilloscope screen to present 16 rows of 12 bit words as 1s and 0s. It was introduced in the January 1974 Hewlett-Packard Journal. Mixed-signal oscilloscopes Mixed-signal oscilloscopes combine the functionality of a digital storage oscilloscope with a logic analyzer. The several benefits of these include the ability to view analog and digital signals together in time, and to trigger on either digital or analog signals and capture on the other. A few limitations of mixed signal oscilloscopes are that they do not capture state-mode data, they have a limited channel count, and do not provide the analytical depth and insight of a logic analyzer. See also Bus analyzer References External links Feeling Comfortable with Logic Analyzers - Keysight Digital electronics Embedded systems Electronic test equipment