DOS ain't dead

A new Expanded Memory Manager (EMM) for XP.
Download: https://sourceforge.net/projects/doszip/files/dzemm

Some differences in behaviour on this compare too the NTVDM's EMM:
Instead of the usual 16M of memory, this will give 256M. However, you may allocate FFFF pages to each handle, and there are 255 handles. There is no 1M-limit on copy, so you could copy 500M from one handle to another in one go.

The update KB2724197 prohibits EMS in XP, and this program works best if this is installed (no EMS). If you already have removed the update, and install this one, it will still work, but the MS version will eat a lot of (all) memory. The manager will then "steal" some of this for its usage. You may right-click the shortcut for the DOS program, select Memory, and in the "Use EMS Memory" box, select none. This will prohibit the MS-EMM manager to install.

This is "work in progress"; so don?t expect everything to work smoothly

I decided to revert KB update (I always do manual updates) as it doesn't seem critical for me but it's good to know there's a better solution.

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DOS gives me freedom to unlimited HW access.

My curiosity lead me to try the driver. I saw that mem really repports 256MB EMS but it also caused problems to existing programs. When I run DN OpenSOurce 7.2.16 it crashed:


(it tells that NTVDM CPU got invalid instruction, Choose close/skip)
So I quickly removed the driver from config.nt

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DOS gives me freedom to unlimited HW access.

> My curiosity lead me to try the driver. I saw that mem really repports
> 256MB EMS but it also caused problems to existing programs. When I run DN
> OpenSOurce 7.2.16 it crashed:

I actually use DN to test if the driver is installed, but that have to be a different version.

> (it tells that NTVDM CPU got invalid instruction, Choose close/skip)
> So I quickly removed the driver from config.nt

For testing you may use a new shortcut, and set the CONFIG.NT to a local directory to avoid messing up the global settings.


I downloaded version 6.4.0 (dn640r.rar), and that crashes.
I looked at the code, and I think the size is a problem:

   if EMSFound then
    asm
     mov ah, 42h
     int 67h
     mov cl, 4
     shl dx, cl
     mov EMSSize, dx


If the total size is 256M dx will be 4000h
I uploaded a new version (dzemm101.zip), and now the total size is set to 32M (dx = 0800h).

I made some changes to load DN, but the actual problem is still there, so I need to do some more testing..

I tried new dzemm 1.01 and can confirm that DN works now. Maybe you can make a commandline option to tell how much EMS will be emulated.

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DOS gives me freedom to unlimited HW access.

The problem with DN (and others) is now fixed.
This was a fail in the Restore Page Map (48h) function.

I set the memory size back to 256M. This will fail the test above,
but DN still works, and also the Borland tools seems to be happy.

> I tried new dzemm 1.01 and can confirm that DN works now. Maybe you can
> make a commandline option to tell how much EMS will be emulated.

There is currently no limit to the size of memory available except for the 16-bit FFFF limit for each handle.
For maximum usage the memory size should be as large as possible.

Testing is needed to see if this creates problems.

> The problem with DN (and others) is now fixed.
> This was a fail in the Restore Page Map (48h) function.
>
> I set the memory size back to 256M. This will fail the test above,
> but DN still works, and also the Borland tools seems to be happy.

Yes, my DN is happy with it now.

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DOS gives me freedom to unlimited HW access.