Hey, quick one (for once)
In my Apple II Europlus i've got all RAM stock (with apple logo and copyright 1980)
Interestingly, one of them is not a 4116 but a 8116
According to specs, this is not a 12V/5V DRAM so I find it odd that it's mixed in the middle of 4116 from "the factory".
Could anyone more experienced than I am explain if these chips are indeed compatible/swapable ?
I haven't used one, but the datasheet specifically says it's compatible with MK4116 - and also requires +5V/+12V supplies:
http://minuszerodegrees.net/memory/4116/datasheet_MB8116.pdf
I am terribly sorry I must have misread, or even stumbled upon the wrong datasheet...
This one is indeed 5V/12V
Well, at least this topic confirms 8116 are equivalent to 4116 (so might be a better deadl second hand who knows)
James Sather listed compatible 16k RAM chip part numbers in chapter 5 of his book Understanding the Apple II, which Archive.org has available for free reading at https://archive.org/details/understanding_the_apple_ii/page/n123/mode/2up?view=theater
Here's a quick list of the basic part numbers and the manufacturers who use them:
The less-common part numbers can be cheaper or costlier, apparently depending on supply vs demand. For instance, uPD416 RAM chips are inexpensive on eBay because they're relatively plentiful and most sellers don't mention the "4116" keyword. But Intel's P2117 chips command high prices when they appear -- I guess there are buyers seeking that exact part number but those specific chips are not very plentiful.