There is a part number on the individual memory chips on the stick. Look those part numbers up on Google Search to find their datasheets. Look at the datasheets to see if they are FPM or EDO chips. That is the surest method. Sometimes a manufacturer will have chips that look nearly identical, whereby one is FPM and one is EDO. The individual chips on the sticks may only have one number different in the part number.

486's can be very particular with which memory sticks work properly, especially if you are using tight overall timings (memory and cache) and large cache sizes. I find that EDO memory on 486 motherboards are more problematic than FPM, even if the board supports EDO. I have found that EDO memory, although it is supposedly like 5-10% "faster", it often requires slower cache timings for a fully stable system. This negates the benefits of using EDO.

I find that using larger stick sizes, like 2x32 MB sticks over 4x16 MB sticks, tend to be more forgiving with respect to memory/cache timings.

Are there any VLB/ISA-only boards which support EDO?

Yes i found that UMC boards works with edo ram.(if it would run stable i cant tell) The nice part of these boards is, they also takes only one simm on the boards.. Most boards you have to pair them in two sticks.

Examples are the ADI TK8498F board and the aquaria systems MB-4DUV / UVC (those are really weird boards..)

Yes iam also trying to find on the identification numbers on the sticks, but some are rare to find, and then i still dont know they are FPM or EDO)

Can somebody tell me in which time scheme back in the days EDO ram was release as successor?

I couldn't measure any performance improvement with EDO. But make sure it's 60ns.

According to some Google searching, EDO was introduced in 1994 and became popular in 1995 when the i430FX chipset was released.

You need to go by the chips part numbers. Some of them can take a long time to find. If you can't find the part number, then try removing some of the alphabetic suffixes from the part numbers. If the data sheet has no mention of the RAM being EDO or "Extended Data Out", then it is most likely FPM memory.

I have also never seen any improvement when using EDO memory in a 486 compared to FPM for the same timings. Same goes for faster 10 ns vs. 15 ns cache. I think the memory/cache performance is controlled primarily (or even exclusively?) by the wait states set in the CMOS. Faster memory/cache may just let you set lower wait states, but there is likely a cap on how much faster the cache/RAM is compared to how low a timing control can get.