Strange behaviour withh RAM on a 286.

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Strange behaviour withh RAM on a 286.

Postby jolurove » 2017-12-02 @ 19:13

I have this 286 board with an AMD @ 16MHz, theh chipset is a P82C206 by CHIPS. Which used to have 1MB of RAM which I recenlty upgraded to 4.

And I see some strange behaviour in performance. With 4MB the benchmark results improve quite a bit, but with 2BM the performance it's actually better than with 4 across the board. Between 10 to 15%.
I tried with and without EMS and XMS, I'm using EMM286.exe, but it doesn't matter because even if I don't use it I get the same results. I also played around with BIOS and Video shadows, always the same.. Have anybody experienced something like this before?
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Re: Strange behaviour withh RAM on a 286.

Postby jolurove » 2017-12-02 @ 19:44

I did memory speed test and it shows 7400Kb/s with 2 MB and only 7300Kb/s with 4MB. The sticks are all identical and putting them in any combination of 2 sticks get me the same speed of 7400
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Re: Strange behaviour withh RAM on a 286.

Postby Jo22 » 2017-12-04 @ 05:36

Good morning,
I don't exactly know the cause for your memory performance drop, but according to the datasheet it's an original NEAT chipset
with lots of neat (pun intended) features, such as memory interleaving, page mode and ROM shadowing.. :)
"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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Re: Strange behaviour withh RAM on a 286.

Postby derSammler » 2017-12-04 @ 08:08

jolurove wrote:I did memory speed test and it shows 7400Kb/s with 2 MB and only 7300Kb/s with 4MB. The sticks are all identical and putting them in any combination of 2 sticks get me the same speed of 7400

+/- 100 kb/s when speed is > 7mb/s is nothing to complain about and within the margin of error. Besides, the chipset most likely adds overhead when having to manage more memory. But again, you are talking about not even 1.5% speed difference here...
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Re: Strange behaviour withh RAM on a 286.

Postby jolurove » 2017-12-04 @ 10:03

Yes... For a 286 the BIOS has plenty of options to play around with.
The memory speed test is just one of the benchmarks I ran.
In 3dbench I get 6fps with 2 MB vs 5.3 with 4. Wolfenstein 3d 9.4 vs 8.2. topbench 42 vs 37. Dr Hardware 3372 vs 3056.
I ran the tests multiple times and with different options and they're always the same.
I guess the board doesn't like 4mb
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Re: Strange behaviour withh RAM on a 286.

Postby keropi » 2017-12-04 @ 10:10

judging from the benchmarks I'd stick to 2MB then - I also have a 4MB 286/16 setup and tbh I haven't found any use for the extra ram... sure one can load a 1MB smartdrive or run win3 (slow on 286 anyways) but other than that it's kinda useless. IMHO it's more important to have UMBs than more than 2mb of ram :)
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Re: Strange behaviour withh RAM on a 286.

Postby alvaro84 » 2017-12-04 @ 17:02

keropi wrote:judging from the benchmarks I'd stick to 2MB then - I also have a 4MB 286/16 setup and tbh I haven't found any use for the extra ram... sure one can load a 1MB smartdrive or run win3 (slow on 286 anyways) but other than that it's kinda useless. IMHO it's more important to have UMBs than more than 2mb of ram :)


On the Hedaka 286 I'm putting together right now you can allocate part of the memory as EMS. And I've found that GLX player can use this EMS so I can play quite large modules that I couldn't play back then before I got a 386. The next limit is the 1MB GUS Classic has, I have to fall back to software mixing (directed to the ESS 688 + YMF262 card I have in there for SB compatibility) where the slow CPU will be a limiting factor.

But other than that, there's not much use of the extra memory. I've even downgraded it to 4MB from 16MB which wasn't completely supported by the motherboard.
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Re: Strange behaviour withh RAM on a 286.

Postby jolurove » 2017-12-07 @ 17:15

Well, After retesting everything multiple times changing all the parameteres I could think of, I left the system with 2MB. As you guys said, there's no really use for that much RAM on such a system, but it's still pretty weird, don't you think?
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