Author Topic: RAM on a 286 - EMS, XMS, UMA, HMA, WTF  (Read 2251 times)

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nemail

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RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« on: August 29, 2018, 12:06:29 am »
Hi

so I've got a beautiful, old 286 up and running again (I love tinkering with old computers) and because I was veeery young when I got my first 286, I can't really remember much about memory management.

What I have found out/done so far:
- The motherboard has 1 MB onboard
- BUT it allows me (via jumper config) to either use 640k conventional memory and "ignore" the remaining 384k OR use 512k conventional memory + 512k of UMA (upper memory).
- I have bought, assembled and installed one of these 2MB EMS cards: https://texelec.com/product/lo-tech-ems-2-mb-pcb/
- If I configure the motherboard to 512k/512k, the biiig downside is, that I'll never get more than 500-something conventional memory free, regardless of how well I optimize driver loading
- If I configure it to 640k/0k, I don't have UMA, don't have himem.sys loaded, don't have UMB and so on.
- EMS memory (link above) is installed and LTEMM driver is up and running, 2MB EMS detected and ready

What I ask myself:
- What would be the ideal config to get as much conventional memory as possible + utilize EMS as good as possible
- Would EMS even be used by any software except games which specifically ask for EMS?
- What about QRAM or QEMM or Above Disc?

btw. himem.sys says "no available extended memory was found" when using the 640k/0k config.

Thanks :-)
 

Offline Ampera

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #1 on: August 29, 2018, 03:08:12 am »
I'd say the best option would be to wire a switch up to the jumper that will allow you to externally switch between that whenever you need more conventional memory, and the UMA can't be used by the current program.

If I had to pick one situation, I'd probably pick more conventional memory, as it's more likely to be used by the average program.
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Offline BravoV

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #2 on: August 29, 2018, 03:56:27 am »
Use Quarterdeck's QEMM and utilize the "LOADHIGH" to free more 640K region.

Just read their documentation as its quite comprehensive.

Offline rdl

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #3 on: August 29, 2018, 04:10:53 am »
Is QEMM still around? That's what I used back in the day for running DOS games on my 486. I probably still have the floppy disk somewhere.
 

Offline Halcyon

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #4 on: August 29, 2018, 09:40:43 am »
Is QEMM still around? That's what I used back in the day for running DOS games on my 486. I probably still have the floppy disk somewhere.

https://vetusware.com/category/System/?cat=2&filter=1

386MAX was another.
 

Online rsjsouza

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #5 on: August 29, 2018, 10:16:04 am »
The UMA was always a PITA to get going - I would stick with 640k/0k and try to use Desqview - IIRC it made a decent use of EMS. Just be sure to download the version that runs on Real mode.

https://vetusware.com/category/System/?cat=2&filter=1

386MAX was another.
Nice link Halcyon! Although I suspect 386MAX will not work in a 286 as it requires protected mode.

Even for QEMM, I suspect it does not work in Real Mode - QRAM was the version that did it. BTW, the command is LOADHI. LOADHIGH was the DOS5.x command that did the same function.

(disclaimer - I am recollecting most of this from deep dark and long unused corners of my memory - take all this with a pound of salt)
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Offline BravoV

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #6 on: August 29, 2018, 10:28:22 am »
Even for QEMM, I suspect it does not work in Real Mode - QRAM was the version that did it. BTW, the command is LOADHI. LOADHIGH was the DOS5.x command that did the same function.

(disclaimer - I am recollecting most of this from deep dark and long unused corners of my memory - take all this with a pound of salt)

Probably you're right, its been for so many years.  :palm:

But you've just reminded me, maybe QEMM won't work for 286, as I remembered there was a brain damaged design on 286 that cant switch between real & protected mode properly, and its only fixed at 386 generation, as these QEMM and similar programs do magic stuff with this real & protected mode thingies, cmiiw.  :-//
 
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Online rsjsouza

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #7 on: August 29, 2018, 01:54:45 pm »
Even for QEMM, I suspect it does not work in Real Mode - QRAM was the version that did it. BTW, the command is LOADHI. LOADHIGH was the DOS5.x command that did the same function.

(disclaimer - I am recollecting most of this from deep dark and long unused corners of my memory - take all this with a pound of salt)

Probably you're right, its been for so many years.  :palm:

But you've just reminded me, maybe QEMM won't work for 286, as I remembered there was a brain damaged design on 286 that cant switch between real & protected mode properly, and its only fixed at 386 generation, as these QEMM and similar programs do magic stuff with this real & protected mode thingies, cmiiw. :-//
You can say that twice! Having EMS was almost useless on a 286 - IIRC only Autodesk made use of that and maybe some more obscure software.
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline David Hess

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #8 on: August 29, 2018, 06:19:28 pm »
Switching between protected and real mode on the 286 was less of a problem than lack of paged memory management.

What you actually want is an EEMS or LIM EMS 4.0 board so all of the unused lower address space can be mapped.

https://en.wikipedia.org/wiki/Expanded_memory

You would be much better off with an old 386 if you want to mess with Desqview and QEMM.
 

Offline abyrvalg

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #9 on: August 31, 2018, 07:40:17 am »
OP’s config doesn’t have any memory requiring PM/MMU. Those 386+ things were used to map memory beyond 1M to low addresses representing it as a fake EMS (mostly), but he has true EMS already.
 

nemail

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #10 on: September 02, 2018, 01:22:16 am »
I'd say the best option would be to wire a switch up to the jumper that will allow you to externally switch between that whenever you need more conventional memory, and the UMA can't be used by the current program.

Now that's one cool idea :D

I guess I'll try again and play around with QRAM (tried that before, when I didn't have EMS yet).

Quote
What you actually want is an EEMS or LIM EMS 4.0 board so all of the unused lower address space can be mapped.
I thought that the lo-tech EMS board is LIN EMS 4.0 compatible...

I have many more vintage computer systems to play around with, I was just curious if there is any way of optimizing this 286 box :-)
 

Offline Halcyon

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #11 on: September 02, 2018, 10:19:22 pm »
Quote
What you actually want is an EEMS or LIM EMS 4.0 board so all of the unused lower address space can be mapped.
I thought that the lo-tech EMS board is LIN EMS 4.0 compatible...

Yes, it is. You just need to install the LIN 4.0 device driver. (It also has a command switch to only support EMS 3.2 mode as well.)
 

Offline innkeeper

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #12 on: September 03, 2018, 01:19:44 am »
I really don't miss the days of dealing with that stuff.
Hobbyist and a retired engineer and possibly a test equipment addict, though, searching for the equipment to test for that.
 

Offline David Hess

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #13 on: September 03, 2018, 02:24:11 am »
Quote
What you actually want is an EEMS or LIM EMS 4.0 board so all of the unused lower address space can be mapped.

I thought that the lo-tech EMS board is LIN EMS 4.0 compatible...

Yes, it looks like it is.

Quote
I have many more vintage computer systems to play around with, I was just curious if there is any way of optimizing this 286 box :-)

I managed to miss the EMS on 286 era although I had a couple of 286s but not the QEMM on 386 era.
 

Offline bitseeker

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #14 on: September 03, 2018, 06:53:55 am »
Before having Desqview on the 386, on the 286 I used to use Software Carousel by Softlogic to switch between programs. It suspends and swaps apps between system RAM and XMS/EMS (or HDD if you were desperate).

Unless you need the EMS for a particular program, Carousel is a cool way to utilize that extra memory for task switching.
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Offline digsys

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #15 on: September 03, 2018, 07:01:46 am »
Quote from: innkeeper
I really don't miss the days of dealing with that stuff.
LOL, I do :-)  The weekly / monthly computer nerd meetings - swapping methods of eeking out another 2K of base memory / ems etc and everyone getting excited -
hero for a day. Then I made my first page swapping card that held 4x 640K installs, and used a 64K share buffer between them !! THAT was living !!!
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Offline In Vacuo Veritas

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #16 on: September 04, 2018, 04:59:29 pm »
Does the latest DOS run on a 286? There was MemMaker that was supposed to tune all that noise.

https://docs.microsoft.com/en-us/previous-versions/tn-archive/cc722463(v=technet.10)
 

Offline rrinker

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Re: RAM on a 286 - EMS, XMS, UMA, HMA, WTF
« Reply #17 on: September 04, 2018, 07:49:11 pm »
 QEMM also had a utility that was supposed to automatically tune the memory utilization. I could always do better manually than either automatic tool.

I used DesqView on my 8088 8MHz clone in college - I ran a BBS on my machine but I also needed to be able to write papers and lab reports and so forth. DesqView was quite advanced - worked very well allowing me to essential make 2 machines from one, the BBS worked at nearly full speed (on campus access was as high as 19.2kbps - when most were lucky to have a 1200 bps modem, let alone a 2400 bps one) AND I had plenty of performance to run a word processor or even PSPICE simulations.

 


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