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NOEMS (Users)

posted by Rugxulo Homepage, Usono, 02.02.2013, 17:03

I love mentioning how Trixter's 8088 has 2 MB of real EMS. Hence it's very useful to him, but obviously newer cpus (286+) prefer something else, usually handled via XMS or DPMI or whatever API non-DOSes use. Turbo C, etc. prefer EMS by default (if available) because, IIRC, "XMS was not quite standardized yet". EMS was standardized by LIM: Lotus-Intel-Microsoft, latest version was 4.0.

I could be wrong, but I think NOEMS only disables the 64kb page frame, hence it still allows EMS 4.0 stuff (4 kb pages?). Ask Eric Auer for more info. 4.0 may have been originally limited to 32 MB (which was probably plenty back then), dunno how officially hardcoded that is elsewhere though. (Wasn't 3.2 maxed out at 8 MB?)

Wasn't Compaq's EMM386 the first to be included in their variant of MS-DOS? Or was it DR-DOS? And wasn't HIMEM.SYS used originally for Windows only?

The irony is that XMS works on 286s but EMM386 only on 386s (in V86 mode). While it's true that some apps conflict with EMM386, usually "most" well-behaved apps work fine with it installed. (And yes, I know there are software-only EMS emulators for 286.) Though I think XMS fragments more easily than EMS. The main difficulty these days with EMM386 is the 4 kb paging, which can cause difficulties with newer cpus and 4 MB pages, etc. (like sometimes used by CWSDPMI, if large allocations are needed).

But I agree, if you don't have lots of EMS apps and don't need UMBs, it's best to not load it. Luckily "JEMM386 LOAD" is there for us when needed.

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