Le Pub des Instruments Électroniques

The second microprocessor, called the voice processor, is located on the
voice printed circuit board.

The voice processor receives the sound parameter data from the main
processor f VCO frequency, LFD 2 speed, envelope 3 attack time etc..) and
generates all the modulations and controls that drive the analog circuitry.
It also performs a number of automatic calibrations and corrections which
insure the accurate behavior of the analog circuitry of each voice

...

VCO TEMPERATURE COMPENSATION:

Each 3374 dual VCO chip used on the analog voices includes a
temperature sensor circuit that provides on pin 10 a voltage proportional
to the chip internal temperature. These voltages are filtered and buffered
on each voice by CX35 and UX05. The six voltages are then routed to US05
in the DAC area. (...) When the DAC loads a sample and hold controlling the frequency
of a VCO, the temperature reference voltage of this VCO will be used as
reference for the DAC. Therefore , If the internal temperature of a VCO
rises, its frequency voltage control will raise proportionally, keeping the
resulting frequency stable.