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Technical Reasons For OS Memory Limitations?

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August 6, 2001 7:00:01 PM

Can anyone tell me, or direct me to a link with some technical reasons for memory limitations in different OS's.

I've heard plenty of what sounds like old wives tales regarding how much memory can and can't be addressed by windows95/98 and windows 2000...

Some people say

"don't put more than 256MB in your 98 system" some say,

"Don't put more than 64MB in you 95 system"... I've heard

"Fill as many DIMM slots as possible if you have 2000"

The problem is I hear different recommendations virtually every time. Can anyone tell me why (if there does in fact exist a memory limitation)? Is there a MS site with definitive information regarding this subject? Please help

-Confused by others confusion
August 6, 2001 8:59:44 PM

windows 98 and me do have a problem with more then 512 mb of ram

if i rember right it has to do with swap files

<font color=red>Gasoline + Fire</font color=red><font color=green> Can be a lot of fun</font color=green> :smile: :smile: :smile:
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August 7, 2001 12:16:41 AM

Here is Microsoft's documentation on the original 512mb limitation with Windows 9x/ME.

<A HREF="http://support.microsoft.com/support/kb/articles/Q253/9..." target="_new">http://support.microsoft.com/support/kb/articles/Q253/9...;/A>

As far as I know with Win2K, the more the better, hardware permitting.

I didn't realize that Cacheman, for which Shuke provided a link, solved the 512mb problem for Windows 9x/ME. That's good news, especially with memory so cheap.

As for those memory limitations that you mentioned, when Windows 95 was first released there were few motherboards that had the capacity beyond 64mb of RAM. Likewise, at the time of Windows 98 few were capable beyond 256mb. Even if your motherboard had the extra capability, (mostly coming at later dates), the cost of memory was prohibitive relative to the gains in performance, especially with the applications of the day.

Today, those physical barriers are gone and memory is cheap but with most applications there still is little to gain by exceeding 128mb of RAM using Windows 9x or 256mb using Windows ME. You might gain a couple or three percentage points. Still, as I said, memory is cheap so why not add more if you wish. Just be aware you may not detect any difference if you do. It depends on the software that <b>you</b> use.


<P ID="edit"><FONT SIZE=-1><EM>Edited by phsstpok on 08/06/01 08:22 PM.</EM></FONT></P>
August 7, 2001 1:40:49 AM

Technically, Windows9x/ME has no 512MB limitation. It's more like a 512MB+ bug. But theoretically, Windows 9x/Me supports up to 2 GB RAM.

Or was it 4GB? I don't remember.
<P ID="edit"><FONT SIZE=-1><EM>Edited by AMD_Man on 08/06/01 09:41 PM.</EM></FONT></P>
August 7, 2001 2:10:37 AM

I don't know about that. The Microsoft documentation states that Vcache is internally limited to 800mb. Sounds like a desing limitation to me.

Actually, I should have mentioned that Cyberimage claims that the problem is elminated if you have enough memory that you can turn off virtual memory. I don't know anyone who has confirmed this and I don't know how much memory would do the job.
Months ago,
August 7, 2001 9:25:41 AM

9X max of 512... NT/2000 any amount hardware permitting

if in doubt blame microsoft...
August 7, 2001 9:27:43 AM

uhm... yeh 3% increase from more than 128 ram with 9X... i got a 75% boot time cut by going to 320 from 128 so i have no clue what youre chatitng about... id say that 256 is a bare minimum for a decent system...

if in doubt blame microsoft...
August 7, 2001 9:30:07 AM

I think 32bit OS's have a 4GB addressing limit. I'm not sure if 2k/xp use any tricks to get passed that.


<font color=red><i>Tomorrow I will live, the fool does say
today itself's too late; the wise lived yesterday
August 7, 2001 9:33:09 AM

9X have bugs limiting you to 512

if in doubt blame microsoft...
August 7, 2001 5:19:06 PM

I was talking about in-application performance not boot times or application load times. The latter, I concede, improves greatly with more memory.

As for Windows boot times, when I upgraded from 128mb to 384mb my boot time went from 73 seconds to 71 seconds for Windows 98SE. Just how slow was your orignal boot time that you saw a 75% improvement?
August 7, 2001 5:32:32 PM

adobe sped up a great deal... much faster image loading and conversions... games... lets not go into that... ok lets... loading times and precaching sped up sooo much its not even funny... 128 megs heavy metal fakk 2 took 3 mins to load each level at 1600x1200 now it takes 35 seconds... windows bootup went from 85 seconds down to 21... having mp3s playing 10 ie windows up... messenger and icq, irc... etc... all running perfectly no delays... perfect... larger agp appeture also helps...

if in doubt blame microsoft...
August 7, 2001 5:59:20 PM

I guess I stand corrected. I wasn't really thinking about multitasking either. I guess I'm a one task at a time kind of guy.

I retract everything I said except the historical references.

At least I said if one wants the extra memory to go ahead and buy it. It's cheap.
August 7, 2001 7:19:42 PM

You should remember that boot times will be fairly constant unless you use <b>faster</b> memory/CPU/HDD. The system needs to run all its POST stuff and then load the OS and the start-up apps.

Unless the Swapfile is already being used for this (I hope not), there shouldn't be a great difference.

<b>
If the best things in life are free, why do I keep upgrading my system? :smile:
</b>
August 7, 2001 11:56:57 PM

Thanks. My boot times are somewhat limited mostly by a 5400RPM hard drive (40 gig really cheap). My memory is MAXed on this old KT7 motherboard, 141mhz (hstclk + PCIclk), CAS2, turbo timing, 4-way interleave, etc.
!