Physiological Monitor

The Tektronix Physiological Monitor might have been a prototype of what became the 410. It is all solid-state except for the CRT.

It has a nickel-cadmium battery pack comprising 10 D-size cells. The battery is center-tapped, providing +6.25 V and -6.25 V when fully charged. There doesn't appear to be any sort of regulator or DC-to-DC converter for the low voltage, just direct connection of the battery to the amplifiers and other circuitry. There is a power oscillator generating the high voltage for the CRT.