Baron already knows what goes there.

B000-B7FF is used for 1bit per pixel graphics memory for graphics modes on hercules/MDA adapters.

B800-BFFF is used for text modes to contain text mode diaplay data.

Their contents will change, based on what is on the screen. They are used to display what is on the screen. 😁

Typically, VGA cards do not fully emulate MDA adapters. The only region they populate is the B800-BFFF region, which is used to store text display mode character data. As such, 'there is nothing connected' at B000-B7FF on most systems with a VGA card, and it is safe to use this area for UMBs.

For whatever reason, (I suspect the ET4000, since it has register-level MDA/CGA emulation) this area is contested on your hardware, and trying to use it as UMB causes a hang. (Which is why I'd like you to try without the ET4000)

The Baron rightly points out that the B800-BFFF region is not going to be safe to use: YOU NEED IT TO DISPLAY TEXT. He mentioned a fringe case where a loaded driver can change the behavior to use the VGA adapter region (A000) instead, but that way lies dragons.

wierd_w wrote on 2026-02-04, 20:03:

... that the B800-BFFF region is not going to be safe to use: YOU NEED IT TO DISPLAY TEXT. He mentioned a fringe case where a loaded driver can change the behavior to use the VGA adapter region (A000) instead, but that way lies dragons.

It's perhaps a lot easier to fix. Just set a graphics mode BEFORE running EMM386. If the VGA BIOS works correctly, any text that is output via DOS or BIOS should then be seen even if region B000-BFFF is no longer under VGA control.

I attached such a tool - it sets graphics mode 0x12. I guess It cannot be tested in DosBox, since it needs to be run in CONFIG.SYS:

1DEVICE=C:\SETM12.SYS
2DEVICE=C:\DOS\EMM386.EXE FRAME=E000 RAM=B000-BFFF RAM=D100-D7FF X=D000-D0FF X=D800-D9FF RAM=C800-CFFF RAM=DD00-DFFF

Try QEMM or UMBPCI. QEMM has many ways to gain more UMBs, and UMBPCI can work on some systems if nothing else works. UMBPCI was the only DOS memory manager that worked on my Win98SE PC at my mother's house in Windows mode. The main problem I had with UMBPCI was that I can't use the mono graphics buffer for UMBs, but that is a minor problem, and everything else worked. You can find it at [utl]https://dosprograms.info.tt/indexall.htm#utils[/url]. Tell me how it works.

^If performance is not important, why not using physical solutions?
The Lo-tech/Monotech 1 MB RAM card and 2 MB EMS card work in Real-Mode and provide UMBs and pseudo LIM 4 EMS.

Does this application require VGA text-mode/soft fonts?
If not, why not use a CGA card with Composite port?
Everything below 736 KB then will be free to use, basically. No MDA in the way.
An external composite to VGA converter will help driving a VGA monitor.

Or just use ET4000 mode utility to switch to CGA emulation?
It's not the best there is, maybe, but it does provide CGA text fonts and CGA register-compatibility.
The mode utility was called vmode.com, I think.
It might be part of my little collection: Re: Realtek realtalk, is it the best VGA for CGA? What is?

Jo22 wrote on 2026-02-05, 05:27:

^If performance is not important, why not using physical solutions?

TS doesn't know anything about i/o cards, they memory-mapped or not , cnc software uses hardcoded mem space in UMB (we know only about e000, but may be more) or not...So hardware ems/umb probably waste of time/money
Also i think cnc software may uses e000 as usual memory, not as EMS, so need it map as umb

Mov AX, 0xDEAD wrote on 2026-02-05, 11:20:

Jo22 wrote on 2026-02-05, 05:27:

^If performance is not important, why not using physical solutions?

TS doesn't know anything about i/o cards, they memory-mapped or not , cnc software uses hardcoded mem space in UMB (we know only about e000, but may be more) or not...So hardware ems/umb probably waste of time/money
Also i think cnc software may uses e000 as usual memory, not as EMS, so need it map as umb

Hi, I'm not sure if I understand (what's a TS?),
but from what I remember is that EMM386 and V86 are not as reliable as hardware solutions and Real-Mode. 🙂

That 1MB RAM card has DIL switches to enable RAM in 64 KB blocks across the whole first Megabyte.
It can be used for creating UMBs by using USE!UMBS.SYS driver, but that's optional.
The 2 MB EMS card can have a page-frame at any standard location, the EMS driver is optional.
There's also an unofficial 4 MB model, too.

Emulators such as 86Box emulate RAM cards, chipset EMS and that Lo-Tech EMS card.
Maybe that helps at trouble shooting the CNC software, not sure.

Another alternative to EMS/EMM386 is EMS Magic, a modern Freeware that used to be commercial.
It's a better alternative to the Freewsre classic EMM286, basically.
Just like it it uses XMS to simulate EMS and installs an EMS page frame in conventional memory.
Above Disc is another classic LIMulator. It has a Windows 2.x compatible mode, even.

About EMM386.. There are different versions out there.
The version shipped with MS-DOS 6.22 and WfW 3.11 is the last classic, which also accepts parameters from MemMaker.
The Windows 9x version supports XMS 3 but doesn't understand MemMaker anymore.

Then, there's the IBM DOS version which is a descendant of the MS-DOS 6 line.
The version shipped with PC DOS 2000 or PC DOS 7.1 might be a good alternative to that.
It is newer, has more features or bug fixes.
I've used the Japanese version in a DOS/V installation once (it fixed issues with Japanese Windows 3.1, I forgot the details).

debnie wrote on 2026-02-04, 19:36:

wierd_w wrote on 2026-02-04, 19:00:

...
Please humor me, in getting the MSD Memory page from an F5 boot, using the integrated VGA.

I will do this tomorrow, does it make sense to do this for other ISA graphic cards (I have 3 or so - all different types)?

Sorry for the late reply (didn't have much time to continue the project). For the moment I tested some solutions that didn't required some reading into (momentarily I have some limited time). But appreciate the help!

So I tested all the ISA graphic cards I could easily find and run MSD. See attached screenshots.

Baron von Riedesel wrote on 2026-02-04, 20:55:

It's perhaps a lot easier to fix. Just set a graphics mode BEFORE running EMM386. If the VGA BIOS works correctly, any text that […]
Show full quote

It's perhaps a lot easier to fix. Just set a graphics mode BEFORE running EMM386. If the VGA BIOS works correctly, any text that is output via DOS or BIOS should then be seen even if region B000-BFFF is no longer under VGA control.

I attached such a tool - it sets graphics mode 0x12. I guess It cannot be tested in DosBox, since it needs to be run in CONFIG.SYS:

Copy code to clipboard

1DEVICE=C:\SETM12.SYS
2DEVICE=C:\DOS\EMM386.EXE FRAME=E000 RAM=B000-BFFF RAM=D100-D7FF X=D000-D0FF X=D800-D9FF RAM=C800-CFFF RAM=DD00-DFFF

I tested the tool with real hardware and using 3 graphic cards.
*The original graphic cards showed the autoexec.bat text again (that was hidden without it)!
*The internal graphic card showed static "snow" and crashed the PC.

But the GUI didn't load.

Jo22 wrote on 2026-02-05, 16:52:

... About EMM386.. There are different versions out there. The version shipped with MS-DOS 6.22 and WfW 3.11 is the last classic […]
Show full quote

...
About EMM386.. There are different versions out there.
The version shipped with MS-DOS 6.22 and WfW 3.11 is the last classic, which also accepts parameters from MemMaker.
The Windows 9x version supports XMS 3 but doesn't understand MemMaker anymore.

Then, there's the IBM DOS version which is a descendant of the MS-DOS 6 line.
The version shipped with PC DOS 2000 or PC DOS 7.1 might be a good alternative to that.
...

Some information on versions used:
MS-DOS Version 6.22
MICROSOFT Expanded Memory Manager 386 Version 4.49

I replaced the EM386 from DOS6.22 with the EM386 from IBM PC DOS 7.1, tested it on real hardware but didn't saw a noticeable difference.

I will read into the other possible things to try...

The Trident, Quadtel, Phoenix, and C&T vga cards all end at (0r before, in the case of trident) C7FF, which would work with the original include starting at C800.

Can you try the B000-B7FF include with these cards?