64MB RAM Limit???

In the past few weeks, I have repeatedly heard about Windows95 not handling more than 64 MB of RAM.  Instead of cluttering the threads for these questions, I decided to open it up to discussion.  I have personally used 128MB of RAM in more than a couple 95 systems but I've seen enough of these "it can't do it" type of posts to really make me wonder what everyone is talking about.  

Please don't post answers.  The only reason I am even posting points for this is that I want solid theory about why or why not.  I will award the most thorough and factually based post.
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I agree with you. I have only been seriously in this business for a little over five years and between school and books i've read,I have never seen anything about 64MB limit with win 95.
My first machine was a win 95 with 80mgs of RAM.
I know there is a Hard disk limit with Win95 A thats a pub. fact.
Now the only limit I have seen is cachable memory. It has to do with Intel Chip sets on your motherboard.
These all have the 64mg limit and are all early Pentium chip sets but they will recognize more than they can cache.
1cellAuthor Commented:
and there is the fact that Win95 build 950 was shipped with a highmem.sys that did a terrible job of handling >64Mbyte.
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1cellAuthor Commented:
please elaborate j2
From what i have read (i never ran the original version of win95), the original himem.sys handler was extremely slow in accessing pages above the 64Mbyte boundry.
It was just a quick modification of the DOS6.22 himem.sys which, if i understand correctly, didnt handle >64Mbyte at all?
From What I have seen or read the 64MB is not a Win95 limitation but the MB or BIOS for the MB, I had a Compaq that I bought in 95 with Win95 as the OS and it would take 136 MB, that was 4 32MB in the simm slots plus 8 on the MB, the BIOS would not allow 2 64MB chips.
Anyway the reason I said that was to show that it is not an OS problem but instead a BIOS one, I have a friend with an IBM rumming Win98 and he can only add one 32MB DIMM to it to bring it to a max of 64MB, according to the manual the only chip you can add is the 32MB one, not a 16MB or even remove the first 32MB and add one 64MB DIMM, the BIOS does not allow this and no updates is available??
The MB I am using right now only allows 384MB (it will never see that much as long as I own it)
Anyway 1cell I have seen some of the same posts that you have and I was wondering what they were talking about myself since I have never seen anything about a limitation of memory by the OS, only the BIOS or MB
"From What I have seen or read the 64MB is not a Win95 limitation but the MB or BIOS for the MB"

Its actually a limit in the amount of memory that all Pentium chipsets _except_ the HX could cache. So yes, it is a hardware thing.

BUT in MOST cases the system is still faster with >64 then <64, since pagin is reduced. The only time you could really see the difference was if the system didnt use all the ram it had even before the upgrade. (of cource, there were buggy cards which suffered regardless)

But as i also stated, the himem.sys shipped with the original win95 was slow in accessing pages >64mbyte, this was fixed in OSR2.
1cellAuthor Commented:
So, what I can gather so far is that this might be a problem with the orignal version of 95.

I have seen exactly what Rayt333 and sorgie are talking about but I'm still curious about some specifics on this.
I did some KB hopping and found some related articles:

Himem.sys Cannot Address More Than 64 MB of Memory:

The information in this article applies to:
[MS-DOS] 4.x, 5.x, 6.0, 6.2, 6.21, 6.22
Microsoft Windows versions 3.1, 3.11, 95

Himem.sys does not report or use more than 64 megabytes (MB) of installed memory on computers with an Industry Standard Architecture (ISA) or Micro Channel Architecture (MCA) bus.

ISA Buses
ISA buses lack a standard BIOS interrupt routine for reporting more than 64 MB of memory. Himem.sys depends on the INT 15 function 88 service to determine installed memory, and this function is limited to 65,535 kilobytes (64 MB).

MCA Buses

This limitation does not apply to computers with an Extended Industry Standard Architecture (EISA) bus. On EISA-based computers, Himem.sys scans each slot for device information, which means that it can report up to 4 gigabytes (GB).
NOTE: You may need to use the /EISA switch on the Himem.sys line in your Config.sys file.

Note that although Himem.sys addresses only the first 64 MB of memory, the...


....Windows 95 virtual memory manager (Vmm32.vxd) takes over memory management tasks from Himem.sys. Vmm32.vxd can address more than 64 MB of memory.

Windows NT Only Recognizes up to 64 MB RAM on Some Computers:

(might be another thing to factor in)
Updated AMI BIOS Needed for Large IDE Drives and 64+ MB Memory
Unable to Detect RAM Beyond 64 MB On HP Vectra XU P5/90
Windows 3.1 Memory Limits
Memory Use Limitations in Microsoft Windows: [version 3]
Interesting ones.


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1cellAuthor Commented:
Now that's interesting!  I think that might be a winner but I'll give another sunrise for more info and to check out the links.
The problem with the 64Mb limit is to do with the motherboard. The amount of memory address lines on older types of MB meant that the maximum that could be addressed was 64MB, You could install more memory, but once you went above the 64Mb limit, the cache was no longer used, and therfore the machine slowed down. Newer MBs have been designed to overcome this problem by increasing the amount of lines in the address bus and therfore, the problem SHOULD no longer exist.
Kazon: Had you bothered to read the entire post, you should see that your proposed answer contains less details then most of the comments. And also the original Q states

"Please don't post answers.  The only reason I am even posting points for this is that I want solid theory about why or why not.  I will award the most thorough and factually based post."
1cell, apologies for posting an answer instead of a comment. I am new to this, and obviously chose the wrong option. I merely wanted to make an observation. It is a pity that there are small minded,arrogant people on this excellent site who get off on having a go at newcomers (obviously a person of little importance in their real life). What a great way to encourage involvement.  
Unfortunately neither slander or sarcasm has any effect on me ;)

I do however think that Kazon should read the sites guidelines in regards to proper behaviour / language.

I merely pointed out that your proposed answer did not contain any information that was not already given above (and in much greater detail).

Anyway, a question thread is no place to hold an argument, if you wish to discuss any problems feel free to contact me directly at spamfilter@x-files.pp.se (yes, it is a valid adress)
You are correct in your comment to Kazon, but I have no doubt the when 1cell checks in that he will reject the proposed answer since that info had already been covered and he did say "no Answer"
Yeap, i see that as the given scenario aswell, i just wanted to give kazon an oportunity to discuss it with me if he feels the need to.
1cellAuthor Commented:
first, I am well aware of motherboards/BIOS limitations

second, as you are new, welcome but please realize that many of the experts here have been fighting a battle for some time with people posting questions in an unwarranted manner which is why I asked that none be posted.  I think what you have taken as insulting is just some one trying to make a strong point which is something I have been guilty of many times myself.  Don't take comments personally.  

Now, back to the thread.

I greatly appreciate all input here.  After hearing many instances of people mentioning these limits with Win95 and not being able to say on a factual basis that it was incorrect, I am glad now that at least the few of us know better and can speak intelligently on the subject.  I think this is the exact reason for a site like this.  We have been able to squash a theory with known facts and we are all now better informed.  Knowledge sharing;  isn't it beautiful?
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