CEM3394 interfacing with a microcontroller

[alkopop79]

I am in the process of designing a CEM3394-based synth with a microcontroller. According to the manufacturer, the IC can be interfaced with a microprocessor (or microcontroller) using a multiplexer. So far so good, I have studied schematics of Akai and Sequential synths and indeed, the multiplexer be connected to the CEM3394 easily with hold capacitors.

https://ibb.co/Xt0k0K7 (sorry, cannot add image or links)

However, the CEM3394's 8 CV inputs all use different CV ranges, both uni- and bipolar.

https://ibb.co/r2Gtp85

VCO Input CF -4 ... +4V
Mod Amt CV 0 ... +4V
Wave Select CV -2 ... +4V
PWM Input CV 0 ... +2,2V
Mixer Balance CV -2 ... +2V
Filter Resonance CV 0 ... 2,5V
VCF CV -3 ... +4V
Final VCA Gain CV 0 ... +4,3V

What I don't see in this Seq Circuits schematic (nor on the Akai one) is signal conditioning. How did they convert the unipolar DAC signal to match the range of CV inputs? Or did they just convert the DAC signal to bipolar to cover all CV ranges? Wouldn't you need some op amp circuits to attenuate?amplify and level shift the DAC signal? I hope my questions makes sense.

ATTACHED: repair manuals with schematics w CEM3394

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Sequential-Circuits-Multitrak-Service-Manual.pdf
Description:		Download
Filename:	Sequential-Circuits-Multitrak-Service-Manual.pdf
Filesize:	5.67 MB
Downloaded:	396 Time(s)

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sequential_circuits_multi-trak_sd615_sch.pdf
Description:		Download
Filename:	sequential_circuits_multi-trak_sd615_sch.pdf
Filesize:	4.81 MB
Downloaded:	215 Time(s)

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Akai AX-60 Service Manual.pdf
Description:		Download
Filename:	Akai AX-60 Service Manual.pdf
Filesize:	6.07 MB
Downloaded:	197 Time(s)

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[icnagy]

If you have a look at the multi track block diagram, just after the DAC there is a DAC output buffer and a DAC sign bit inverter, both connected to a 4051 "DAC sign bit switch". The range limiting is probably done in software.