[joezydeco]

Yes. A lot of external clock/calendar chips use a small amount of CMOS RAM to retain the registers. The objective is very low power consumption when the main power bus is off and the device is drawing off of battery or capacitor.

A common part I use is the Epson PCF8563, for example.

https://www.nxp.com/docs/en/data-sheet/PCF8563.pdf

Now the PS4 doesn't seem to have an external chip from the teardowns I've seen. And the term "CMOS Battery" makes no sense other than shorthand for "battery that backs up CMOS memory".

But I'd wager the gates on the custom Sony silicon responsible for keeping time are CMOS or similar technology to minimize power when disconnected from mains (and how often is that? I'm curious what their design criteria is for that).

[fomine3]

Thanks. I didn't know that RTC chips use CMOS RAM.

> And the term "CMOS Battery" makes no sense other than shorthand for "battery that backs up CMOS memory".

Nowadays BIOS is replaced by UEFI but we sometimes still call it "BIOS", so I thought that possibly "CMOS" battery is same story.