William Hewlett and David Packard graduated from Stanford in 1934 as electrical engineers.  Four years later they started business in Packard's garage with HP's Model 200A audio oscillator.  One of their earliest customers was Walt Disney - his studio bought several 200B oscillators for use in the production of Fantasia.  The feedback circuit that they designed provided the foundation for other early HP products such as distortion analyzers.  World War II resulted in a flood of orders and rapid company growth.

After the war HP entered the microwave field and expanded with a line of signal generators.  In the 1950s they introduced the first modern frequency counter - the 524A, and began to produce plotters.  They also produced one of the best known of all HP instruments - the 400D VTVM, anchor of a diverse line of voltmeters.

In the 1960s HP moved into other electronic fields such as medical electronics and analytical instrumentation.  They produced a cesium-beam atomic clock which was flown around the world to set international standards of time.  The company entered the field of computing with the 2116A controller for instruments.  They followed with the 9100A desktop scientific calculator.

In the 1970s and 1980s HP expanded their digital electronics line with extremely successful hand-held scientific calculators, minicomputers and personal computers.  The 1980s saw the introduction of their laser and inkjet printers for PCs.  In 1999 the original core business of instrumentation manufacturing was spun off as Agilent Technologies.