Hi Klov,
I am mostly a pinball guy, but my NVRAMs will work in many other applications including arcade games.
The device FM16W08 is used on all my adapters. It is 70ns rated FRAM (FLASH) chip that acts like a CMOS ram in most situations. It has high enough endurance to last 190 years of read/writes at 1MHz. Holds memory for 10+ years between power cycles.
The main thing you need to pay attention to when using FM16W08 based adapters to replace other battery backed CMOS RAM is that that FM16W08 FRAM chip must have the CE pin cycled for every read/write or it will not work. All pinball applications seem to do this, but i have a report PAC-LAND failed to work with my 6116 adapter. Reviewing the schematic I see why. Midway got lazy with ram and just uses the R/W pin (i think this wastes energy and makes the RAM run hotter).
You can see on the attachment 1 here from PAC-LAND. (2018 is 6116). that the CE pin is just tied to ground. This is not going to work with FM16W08 NVRAM
You can see on attachment two from Bally Pinball 6803 MPU. The CE is is attached to a A LS10 logic gate instead of just grounded. This is what you want to see when using NVRAM.
Any questions about compatibility, I can tell from a schematic in most instances if a NVRAM based off of the FM16W08 is going to work. I didn't even really think about this being an issue because all pinball boards cycle CE for the RAM chips.
As far as Robotron and switching power supplies. I honestly do not know and didn't even think about it. I would assume if the CMOS RAM works with a switching supply, than the FM16W08 based devices would as well. I suppose how fast the rails collapse could effect things. My testers used games with original linear power supplies. I am using the wide voltage part. It has a workable voltage range of 3.3v to 5v, that may help problem boards over say the FM1608 which is a 5v only part.
http://nvram.weebly.com
Andrew