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DOS memory management #111530
12/07/17 03:30 PM
12/07/17 03:30 PM
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EoceneMiacid Offline OP
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EoceneMiacid  Offline OP
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Hi,

Lately I've been having some fun setting up my ideal DOS machine in MAME, but it's been at least two decades since I've worked with autoexec.bat's and config.sys's, so I'm probably a bit rusty.

I used the preformatted 2Gb HD image and the Win98 boot disk (from the 'MESS OS installs' thread) to start with. I sys'ed c:, copied the DOS utilities to c:\dos and put c:\dos in the path. CDRom and mouse drivers are loaded.

The only problem I run into is that DOS doesn't appear to use any upper memory at all.

This is my config.sys at the moment:

Code
DEVICE=C:\DOS\HIMEM.SYS
DOS=HIGH,UMB


And this is autoexec.bat:

Code
SET PATH=C:\DOS


If I boot with this configuration and run mem I get:

[Linked Image]

So what's wrong here?

Last edited by EoceneMiacid; 12/07/17 09:28 PM.
Re: DOS memory management [Re: EoceneMiacid] #111532
12/07/17 03:35 PM
12/07/17 03:35 PM
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crazyc Offline
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You need emm386 or some other pmode memory manager like qemm to use umbs.

Re: DOS memory management [Re: EoceneMiacid] #111533
12/07/17 03:45 PM
12/07/17 03:45 PM
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EoceneMiacid Offline OP
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With this line present in config.sys:

Code
DEVICE=C:\DOS\EMM386.EXE


... and rebooting, mem returns the same values.

Whether I use DEVICE or DEVICEHIGH, LOAD or LOADHIGH doesn't make a difference, it's all loaded in conventional memory.

Re: DOS memory management [Re: EoceneMiacid] #111534
12/07/17 03:49 PM
12/07/17 03:49 PM
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crazyc Offline
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I think use need to use the ram or noems switch for emm386 to map the umb.

Re: DOS memory management [Re: EoceneMiacid] #111535
12/07/17 03:55 PM
12/07/17 03:55 PM
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EoceneMiacid Offline OP
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Oh wait a sec, found the problem. emm386.exe isn't present on the win98 boot disk. The file's simply not present ;x I foolishly assumed it was.

Last edited by EoceneMiacid; 12/07/17 09:29 PM.
Re: DOS memory management [Re: EoceneMiacid] #111536
12/07/17 04:21 PM
12/07/17 04:21 PM
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EoceneMiacid Offline OP
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But copying the the latest version of emm386.exe (and the NOEMS switched added), still doesn't make a difference?

Last edited by EoceneMiacid; 12/07/17 09:30 PM.
Re: DOS memory management [Re: EoceneMiacid] #111537
12/07/17 06:37 PM
12/07/17 06:37 PM
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crazyc Offline
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The at486 driver with device=emm386.exe ram and dos=high,usb gives me 28K of umb ram. C8000 though D8000 is the ems page frame so it could have 64K more with noems.

Re: DOS memory management [Re: EoceneMiacid] #111538
12/07/17 06:49 PM
12/07/17 06:49 PM
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EoceneMiacid Offline OP
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That's it - by switching to the at486 driver (instead of the ct486 which I used) but using the same disk image, the problem is fixed now:

[Linked Image]

Last edited by EoceneMiacid; 12/07/17 09:28 PM.
Re: DOS memory management [Re: EoceneMiacid] #111539
12/07/17 06:55 PM
12/07/17 06:55 PM
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crazyc Offline
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The cs4031 chipset in the ct486 driver permits detailed configuration of the memory layout. There might be settings in the bios that will make emm386 work.

Re: DOS memory management [Re: EoceneMiacid] #111540
12/07/17 08:24 PM
12/07/17 08:24 PM
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EoceneMiacid Offline OP
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Good to know. I'll stick to at486 for now.

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