However megaem requires VCPI

dosbox CAN provide vcpi services, but only for a limited number of
special games as if always enabled along with ems we'd have to
switch to v86 by default which would kick out lots of games.

So if you can compile the sources of dosbox it'd be quite easy to
test the builtin vcpi host (no need to boot msdos and stuff).

Yes, on linux I've build from cources (0.70 stable) myself, but was unable to find any configure switch to enable or disable support. And it does not provide vcpi (to megaem). I cannot find any refence to VCPI except in files ChangeLog, NEWS and src/ints/ems.cpp which look fine and I cannot seem to get how to enable it for particular application.

When I played dos games on real pc my config was always with emm386 providing ems and umb, and never had any problems.

btw with device.com from qemm i do not need msdos. it loads bin drivers as if they were not stipped from the real exe.

1#define ENABLE_V86_STARTUP 0

to

1#define ENABLE_V86_STARTUP 1

in the ems.cpp

Not sure if the v86mode startup still works. If it doesn't, look further at
ems.cpp for this code:

1	case 0xDE:		/* VCPI Functions */
2		if (!vcpi.enabled) {
3			LOG(LOG_MISC,LOG_ERROR)("EMS:VCPI Call %2X not supported",reg_al);
4			reg_ah=EMM_FUNC_NOSUP;
5		} else {
6			switch (reg_al) {
7			case 0x00:		/* VCPI Installation Check */
8				if (((reg_cx==0) && (reg_di==0x0012)) || (cpu.pmode && (reg_flags & FLAG_VM))) {

and remove those if () checks down there so vcpi services are
reported unconditionally.

and I cannot seem to get how to enable it for particular application

This is intentional.

1(cpu.pmode && (reg_flags & FLAG_VM)

thought that that part would be valid. although it wouldn't hurt to remove it.

Yes but no idea how bad it crashes when v86mode is enabled at startup 😀

Did all three things but when trying to run megaem

"Exit to error: IRET from pmode to v86 with CPL!=0"

in dynamic, normal and full core (if it there is full now, but dosbox is not complaining)

Also other things seem to be broken (like that parlap extender, with error "Paging requested without PE=1"). However pharlap extender run very fine under real pc with emm386 and now it does not.

I am not very good at progaming but it seems that page frame of the internal implementation is at E000, and size is 64k. However every EMM i've found says there is a ram or rom piece in the frame at his location and thus criples it serices. Does dosbox put same data there if ems=false in the config. If so could it be made to no fill this area and then use some "userland" emm like Jemm386?

However every EMM i've found says there is a ram or rom piece

Well that's because emm386 is a bit stupid.

Also other things seem to be broken

When starting up with v86mode? That's why it's disabled by default.

"Exit to error: IRET from pmode to v86 with CPL!=0"

I could get it to start up, but it says something about not being able to
communicate with the tsr. So better try around with emm386-stuff
when booting xydos.
Try loading it with "device=emm386.exe /frame=e000 ram" or how ever
that frame command is spelled (frame: or /f= or something like that).

ms dos FRAME=e000 is ok or M9 is the same, however it allows runnig without frame with NOFRAME, and when running EMM386 it says everything is fine and it provides ems ram and services, but dosbox's mem does not see it ems. Also megaem does not see ems memory but sees vcpi and is happy. Problem is megaem loads in low-dos mem, leaving with around 300 free.

It (ems manger finds rom or ram in the buffer) does not happen only with ms dos emm386 but also with 7-8 emms I've found on the net, some like qemm and 286 based emms does not run at all, some like jemm (which is based on the freedos one) run and compain the same.

I guess I'll stick to that now, where 300-330k lowmem is ok and no extender game/app.

If I find time I may try to dump with debug the memory area and see if there is something written in.

however it allows runnig without frame with NOFRAME

Didn't really understand your posting. Are you using device.com for
this (doesn't work for this, promised) or booting xxdos? In the 2nd case
you're missing upper memory?

Using device.com to load microsofts emm386.exe with noframe.
It happuly says:

emm386 successfully installed.

available expanded memory 7104kb
lim/ems version 4.0
total expanded memory pages 486
available expanded memory pages 444
total handles 64
active handles 1
page frame segment NONE

total upper memory available 47 kb
largest upper memory block available 43 kb
upper memory starting address e000 h

emm386 active.

dosbox's mem says
619 kb free convensional
6640 kb free extended

mem is set to 8, xms, ems, and umb are set to false.

however msdos orginal mem (on mounted directory) says:

655360 bytes total conventional
635392 largest executable program size

7667712 bytes total EMS memory
7045120 bytes free EMS memory

7340032 bytes total contiguos extended memory
0 bytes available contiguos extended memory
6799360 bytes available XMS memory
MS-DOS resident in HMA

Maybe the memory manager structures of dos emulations are not fully msdos compatible.

here are some screenshots http://hristo.todorov.googlepages.com/dosboxems

BTW It seems very strange to me that various emm mangers I've tryed find data in E000 segment either with device.com or with real dos from disk image. Wihh debug memory area is clean, and i can fill and compare fine with different patterns.

however msdos orginal mem (on mounted directory) says

Yes but where's the problem, does that megaem work or not?

Megaem works to the extend where it cannot find ems and loads in conventional (it finds vcpi services and no ems). In fact no other program (beside the ems manger and dos's mem) cannot see there is EMS mem.

Boot dos, and use device=emm386.exe I=D000-EFFF

Many thanks, it's runnig fine now 😀
In realdos (6.22) megaem sees ems memory, so I suspect the dos implementation of dosbox is not fully complete yet 😀 Also extender games not compainig for procesor mode (exatly that way it was with real hardware). Only having an image is a minor discomfort.

Sorry for the ludicrous bump! Did you eventually get megaem working? if so, what was the procedure to do so?

This stuff needs v86 mode and dosbox's vcpi technique avoids using it (too messy,
remember all the crashes because emm386 was loaded?)
So your best bet is booting an msdos image where you load emm386 in the config.sys

when i used a dos image i seemingly lost all gus support! I got emm386 to work with qemm's device.com but tis not perfect (thoug megaem will run)