CraigAB69 wrote on 2023-01-01, 10:39:

Yea, I don't know mate. […]
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Jo22 wrote on 2023-01-01, 10:25:

I'm using an MS-DOS 6.22 VM with QEMM 9 in Virtual Box 4.1.12..
I've created it a few years ago when I was testing DESQView/X, I believe.

Yea, I don't know mate.

I have been using that Dos 6.2, Win 3.11 for about 12 months now and it ran as expected. Install Qemm and strange crashes started.

Qemm has been removed, and stability has returned.

I don't really have time to dig into it at the moment and RTFM.

The TECNOTE directory didn't even help, nor the 2 books on Internet Archieve.
Which is is why I was looking for a KB.
I even tried to look for quaterdeck.com on WayBackMachine, be even those snapshot redirected to porn sites.

I feel your disappointment.

Yeah, I guess QEMM is less stable than MemMaker/EMM386.

But I assume that's because QEMM was made with 90s hardware in mind - 386, 486 and early Pentium.

All that dark magic that QEMM did use was very low-level and specific to the technology of the day.

AT BIOS, motherboards and CPUs have drastically changed since.

The meaning of certain undocumented CPU instructions have changed, the instruction timings have changed.
The cache design has changed, the CPUs became superscalar etc.

CPUs got so fast that the timing-loops in certain applications do fail now (VBox VMs can be throttled).

So that might be part of the problem. 🤷‍♂️

Also, the Stealth option seems to be most tricky.
It *works* on my real Pentium 133, but sometimes things just hang.

Jo22 wrote on 2023-01-01, 11:53:

I feel your disappointment. […]
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I feel your disappointment.

Yeah, I guess QEMM is less stable than MemMaker/EMM386.

But I assume that's because QEMM was made with 90s hardware in mind - 386, 486 and early Pentium.

All that dark magic that QEMM did use was very low-level and specific to the technology of the day.

AT BIOS, motherboards and CPUs have drastically changed since.

The meaning of certain undocumented CPU instructions have changed, the instruction timings have changed.
The cache design has changed, the CPUs became superscalar etc.

CPUs got so fast that the timing-loops in certain applications do fail now (VBox VMs can be throttled).

So that might be part of the problem. 🤷‍♂️

Also, the Stealth option seems to be most tricky.
It *works* on my real Pentium 133, but sometimes things just hang.

Yes, I would agree, that there is something in those low-level calls. 386MAX was making low-level calls and crashing the VM.
Unfortunately, I am not knowledgeable enough to trace them through the VM.
Perhaps 86Box adheres more closely to the old hardware such that Qemm has no problems.
Only problem with 86Box is that I have never been able to get NetBIOS etc working on a Windows host.
I might give it a go in the morning. It is 2315h here in Australia, so I need to get some sleep.

Playing around with 86Box too, and today, my search for alternatives to EMM386 brought me back here.

In my 386DX-33 "machine" configuration in 86Box with 4MB RAM with 2MB EMS "board" and MS-DOS 5.0, I get 612K free conventional RAM with EMM386 NOEMS. I noticed that the EMM386 from DOS 5.0 takes up about 8.2K of RAM.

Whereas, in my 486DX2-66 with 16MB RAM "machine" I have 618K free conventional RAM. The DOS 6.22's EMM386 seems to take up only 3K of RAM.

Trying to squeeze out as much free conventional RAM seems to be very addictive and it seems like playing a puzzle game itself.

Not many games or applications need more than 610K, let alone 600K RAM. The first game I saw that required me to free up more than 600K of Conventional RAM was Falcon 3.0. Most programs require only around the 580K mark. And to further downplay the importance of high free available base RAM, later programs at the end of the DOS era started utilizing Extended Memory and doesn't require much of Conventional RAM.

But this doesn't stop us from maximizing the available free Conventional RAM. I even try loading to specific regions manually even after MEMMAKER, if I feel I can get more. As I said, for me, it's addictive to squeeze out as much as I can. Maybe I should stop being so obsessive. 🤣

I like QEMM. I once had a 486SX DOS desktop and installed QEMM on it. The system had a lot of drivers loaded, including CD-ROM drivers, mouse, ANSI.SYS and DOSKEY, but I wasn't getting any more than occasional out of memory errors. However, I installed QEMM on it, anyway, and bought a lot more memory in DOS mode. 😀 It worked well, there. 😀 However, it didn't work properly on a Win98SE minitower I used to have: IIRC, the computer stopped just after the QEMM driver loaded. I believe that version was 97. It seems to work on a new Win98SE minitower in DOS mode, but, as soon as I start Windows, I get an exception. 🙁 If it helps, the new system has a Pentium4 processor and 1GB RAM.

BTW, I like all of QEMM's trickery and what it does to system memory. 😀 It does have some compatibility issues, though. 🙁

Yes, QEMM can really salvage a lot of free available conv. RAM. Which is quite impressive with it's OPTIMIZE process. And I did come across a few games that couldn't work with QEMM. Especially when it used the aggressive shadow ram salvaging.

If yo can not enable umbs the PCI or 486 way. Then yes QEMM97 is the best bet.

I did not use QEMM back in the day, because I was a snot-nosed kid then, and had no money.

Quarterdeck wanted moola for that product, and that was something I had precious little of. I *DID* work for a mom&pop repair place back then, so I got to deal with "Problems" involving QEMM (usually involving its Stealth feature, or with it finding "holes" in option roms, and poking UMBs in them), but that only really just gave me an unfairly negative bias on it.

Sadly, QEMM tops out at 256mb of RAM, while later versions of HIMEM and EMM386 could do upward of 3GB of RAM. (Very useful in DOS systems, if you want to use something like XMSDSK)

wierd_w wrote on 2023-07-30, 06:43:

Sadly, QEMM tops out at 256mb of RAM, while later versions of HIMEM and EMM386 could do upward of 3GB of RAM. (Very useful in DOS systems, if you want to use something like XMSDSK)

How do you get the MS-DOS's HIMEM to access more than 64MB RAM?

Malik wrote on 2023-07-30, 22:30:

How do you get the MS-DOS's HIMEM to access more than 64MB RAM?

If you're referring to MS-DOS 6.x, as well as Win3.x, HIMEM is capped at 64MB. It's possible to access more XMS on DOS 6.x by using a modern driver, I think.

Later DOS such as Win98's DOS7.1 comes with an improved HIMEM that supports more than that. The 256MB cap of QEMM386 is because it uses its own XMS manager.

Except MS-DOS 8.0 (which has an embedded and functionally limited HIMEM built-in), you can always use a more advanced XMS driver to overcome the limitations.

Malik wrote on 2023-07-30, 22:30:

wierd_w wrote on 2023-07-30, 06:43:

Sadly, QEMM tops out at 256mb of RAM, while later versions of HIMEM and EMM386 could do upward of 3GB of RAM. (Very useful in DOS systems, if you want to use something like XMSDSK)

How do you get the MS-DOS's HIMEM to access more than 64MB RAM?

Win98's version of himem.sys will happily work on older DOS versions, IIRC.

https://www.uwe-sieber.de/umbpci_e.html

Try umbpci on pci Systems 😉

EMS can be enabled with EMSMAGIC if needed.

matze79 wrote on 2023-08-06, 21:28:

EMS can be enabled with EMSMAGIC if needed.

Interesting... UMBPCI+EMSMAGIC. I wonder if anyone ever tried this before. It seems to target NTVDM usage but can also be used for real DOS...

From the manual it seems it can allocate EMS page frame (64K) in conventional memory and can be loaded/unloaded anytime. All those features look very good, but I wonder if games requiring EMS would happily cooperate...

I only had Virtual Pool and some Disney games as memory hungry games.

Ultima VII Pt. 2 is my ultimate nemesis with regards to free memory requirements. My 14 year old self nearly went crazy trying to run it on MS-DOS 5.0 at the time..

LSS10999 wrote on 2023-08-07, 05:56:

matze79 wrote on 2023-08-06, 21:28:

EMS can be enabled with EMSMAGIC if needed.

Interesting... UMBPCI+EMSMAGIC. I wonder if anyone ever tried this before. It seems to target NTVDM usage but can also be used for real DOS...

From the manual it seems it can allocate EMS page frame (64K) in conventional memory and can be loaded/unloaded anytime. All those features look very good, but I wonder if games requiring EMS would happily cooperate...

Can also allocate in UMB

matze79 wrote on 2023-09-19, 04:41:

LSS10999 wrote on 2023-08-07, 05:56:

matze79 wrote on 2023-08-06, 21:28:

EMS can be enabled with EMSMAGIC if needed.

Interesting... UMBPCI+EMSMAGIC. I wonder if anyone ever tried this before. It seems to target NTVDM usage but can also be used for real DOS...

From the manual it seems it can allocate EMS page frame (64K) in conventional memory and can be loaded/unloaded anytime. All those features look very good, but I wonder if games requiring EMS would happily cooperate...

Can also allocate in UMB

It helps in case you cannot allocate in UMB, particularly if you use AHCI or off-chipset storage ports (onboard or discrete) that come with their own option ROMs. Most likely you'll end up without a suitable contiguous UMB of 64KB which means existing EMS solutions are out of question.