I like the use of high-res photos instead of live video for the detailed parts of the details.
What I find interesting is that the 2302/2306 battery simulators use a display with much better contrast (VFD?) when new than the closely related
2303/2304 high speed power supplies. Cost cutting? Were they worried about aging? They have the same terrible controls, however.
So the separate section with the slope converter is probably this.
I imagine the ADC handles both the readback and the separate DVM channel. Note that the DVM channel has to stay between -5 V and +30 V from the negative output terminal. In the thread about the 2304A I linked below, TiN says that they report the full 6.5 digit value via GPIB. Accuracy will obviously be worse than a true 6.5 digit DMM due to the voltage reference.
The second channel's operation seems to be very different than the first channel?
The specs are a bit worse for the second channel and it lacks the variable output impedance, probably because it is intended to simulate a charger (which might be a plain SMPS power brick in real life). Not sure what you mean by very different operation? From the front panel they work exactly the same, and I would expect the circuit to be very similar.
What I like over these devices over the Agilent battery simulators from the same era is that they let you program the sink current. So it can function as a true programmable two-quadrant power supply. Maximum current is quite limited however, especially at higher voltages. This unit was clearly optimized for ~4 V operation. The half-rack Agilent units will have a fixed maximum sink current.
They could (at least before this video came along
) be found relatively cheaply on eBay (around $200). Probably a bunch of cell phone design places that dumped them for newer models.