Channel Surfing: HP 3421A

The 3421A Data Acquisition/Control Unit (silver, by the subject’s knee) could measure voltage, resistance and frequency for up to 30 channels. Developed originally for the 41C calculator (shown here in the subject’s hand), an optional adapter would later enable its use in other Hewlett-Packard calculators and computers. Among the employees who contributed to the product’s design was Vicky Sweetser, who would go on to become a development engineer in the Loveland Instrument Division.