I don't think so. Ultima 7/Turrican II/Virtual Pool/Mag Das Magazin from my memory definitely have problems:
That's still very few games. BTW, Virtual Pool (assuming you are talking about this version) definitely works even with EMM386 as I played it on my system. Ultima 7 and Turrican I think I never tried to play, but I believe they can be incompatible, based on those forum posts.
Overall I bet there are more games that actually need / can use EMS compared to games that are truly incompatible with protected mode. Heck, even MSCDEX can use EMS to free more conventional memory.
No, the situation is definitely not like this at all. Those posts (like most related posts) exaggerate the compatibility problems and downplay the usefulness. They also follow the stupid trend of suggesting the billion-configuration startup files, where at most you need two (and in many cases just one is enough).
I have a feeling that many folks have gotten into the retro scene, when it was already retro, and base their knowledge on a lot of hearsay. I have been running DOS and DOS games when it was not retro, but simply the thing (early to late nineties); most of my knowledge is first hand experience. When I say that very few games have problems with EMM386 (much less with the EMS aspect of it), that's because I have found it true on the systems I have used (a Pentium and later a K6-II). When I say that a single startup configuration covers 99% of the use cases, that's because I have found it true on the same systems, with the games I wanted to play.
Granted, there may be substantial differences in the sample of games which shift the balance. I think it's theoretically possible that earlier games (from the 80s) have been coded without expecting protected mode, without being tested in protected mode, and may really have compatibility issues. But what I would like to see (if possible) is an actual list of games, not some vague references (which is what is usually brought into the discussions).
Also the need of using LFB or cache optimizations is not so rare/exotic as you may think. Modern BIOS versions seldom contain options to disable cache levels for slowing down programs, and speed related issues are real.
This point is interesting, and may be relevant specifically for cases such as this one when somebody wants to play DOS games on real hardware on a very modern system. On an actual retro system (say K6), there are hardware methods for slowing down + simple software slowdown utility can be sufficient. But when you have to slowdown a Pentium 4, or a Core CPU, it seems reasonable that you may need more of those real-mode-only tweaks.
All in all, if I went nuts and decided to setup a modern system to run DOS on real hardware (instead of just using DOSBox and forgetting about all this compatibility crap), I would probably start with the same single-config that I've been using, with EMM386 (or perhaps with JEMM386 if indeed it can provide some extra compatibility without sacrificing the ability to find and utilize UMBs). If I hit some actual incompatibility with games, and not a one-off thing that I could get around by just hitting F5 to get to raw DOS without ant driver, I'd add a second config with UMBPCI (since it's likely I'd still need some upper memory blocks to free conventional memory). And hope that my sound card does not require EMM386 for SB emulation (is there even such a card?)
Does UMBPCI work reliably on every PC? I recall reading somewhere that it is chipset-dependent, but I am not sure.
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