Set ems=false in your dosbox.conf, gives 634k+127k compared to 670k+72k.

I am trying to get > 670K of conventional memory and >72.2K UMB available in Dossbox. My current setting are xms= true, ems=false and umb=true which gives me 634K of conventional and 127K of UMB. Are there any other setting changes I can make to get more convertional memory ? Appreciate any help.

impossible. also in real dos.
the limit is 640 kb

Mod Edit: Brian, I have merged your new thread with the old one.

impossible. also in real dos.
the limit is 640 kb

That's a nasty trick here, which works if no ebda etc. is present:
using the video area as ram (emm386 and similar can provide
ram pages in that area). Even under real dos this was a very
fragile thing to do.

I am trying to get > 670K of conventional memory

Why?
Run your program in dosbox and post here what exactly it states
instead of doing some fancy preparation which might be unnecessary.

there are computers with a BIOS that lets you adjust the amount of conventional memory above 640KB...

Yes but they can't provide continuous 640k+ ranges then unless they have
a similar technique of shadowing the graphics area. So this would only
be useful for TSR loading, not this case here (if it's really about an app
needing that much memory).

Hi Wd and all. Unfortunately this app does require an inordinate amount of DOS memory. As requested I ran the App in Dosbox and it does run error free UNTIL I try some high memory usage activities like generating some reports. It then crashes for a “No more heap memory left”

Is there any way to configure Dosbox to mimic the memory setup in the config.sys at the top of this post ?

It then crashes for a “No more heap memory left”

Try with ems=false and xms=true, then use "LH app.exe" to start the app
and see if it works for large memory requests.

Is there any way to configure Dosbox to mimic the memory setup in the config.sys at the top of this post ?

No, and i think it even does not work in Bochs as they have the ebda right
below the graphics area, so the memory block would not be continuous.
But you might want to try it with bochs nevertheless.

Wd, tried with LH and it worked. System didn't crash on high memory tasks. I now have one remainig problem though, this app uses a ISA card http://www.digi.com/products/serialcards/pcx.jsp to obtain 8 serial ports. The app has the required drivers for this card built into its code. So under dos when you launch the app you can access the 8 serial ports. However under Dosbox none of the serial ports are functioning. Any idea how to enable them under dosbox. What edits would be required to dosbox.conf ?

Thanks for all your help to date .

Now you've worked on the memory issue for nothing... 🙁

what's the limitaion of dosbox which prevents this card from functioning ?

DOSBox don't provide direct access to the underlying hardware. Remember, DOSBox can run on almost everything: PC's, Mac's, XBox 360, Playstation Portable (PSP), etc, etc, and the underlying hardware in those boxes is very different.

DOSBox can fully(?) emulate access to certain common PC hardware like sound cards and video which games require to function, and limited access to more rare devices like serial ports. But it does not provide direct hardware access to network cards, or in your case specialized ISA cards.

However.... with enough financial incentive it might be possible to talk one of the developers into providing the required access for your card.