I'm installing Windows 95 (OSR2.5) on a semi-modern PC.

The PC has ran Windows 3.1 and even a version of 2, but I just can't seem to get 95 to work.

after installing it, then fixing a memory error, I tried to install the Fix95CPU patch on the pc, and it installed correctly.. except, it did not, as I still get a protection error, this time though, without any message. just:

Windows protection error. You need to restart your computer

So the patch doesn't work, and I know it can't be the memory

does anyone know how I can get this to work? such as editing some system files?

Here are my PC Specs:

CPU: Intel Celeron.

GPU: Nvidia GT9600 (version with red circuit board, and only VGA).

RAM: 1GB, but there was an easy fix for Windows 95 (system.ini).

CD/DVD ROM, Windows 95 is burned on a CD.



(for the record, I know that it is an old operating system, but as said above, it ran older ones)

Edit for extra information:

Before the main bootscreen, an error message along the lines of:

invalid file MSDOS.SYS file:winver=4.01

although, right after this, the main bootscreen starts, and then the "protection error" shows.


second, here are the patches I used:

CPU patch: Fix95CPU

RAM patch: C:/windows/system.ini >>> added "MaxPhysPage=3B000" to stop giving me error messages

(worked in Windows 98, although I know they are two very different operating systems)

  • 2
    What are the PC's specs?
    – Renan
    Sep 20 at 0:49
  • @Renan I think its this: Intel celeron (not sure what version) 1gb RAM (i used a system file edit to fix the memory thing) nvidia GT 9600 (not too sure about this either, Sep 20 at 6:44
  • You didn't say how much disk you had. W95 cannot handle more than 32Gb so you will have to partition the more modern disks to smaller partitions.
    – cup
    Sep 21 at 4:43
  • @cup let me add that right in. i think its 256GB. would making a partition around 20gb help? Sep 21 at 8:33
  • You won't be able to install W95 on a 256Gb disk. 20Gb would work. Anything over 32Gb would come up with a -ve number.
    – cup
    Sep 21 at 17:11

1 Answer 1


You don't say what "easy fix" you applied. You should be more explicit (setting name, and where did you find information documenting that fix.

I am going to guess you went to in Wikipedia's article for Windows 95 and found the link to Microsoft's Q253912 article (as archived in archive.web), which mentions a cache size adjustment in that file. If so, you didn't investigate the link in Wikipedia right next to that one, the one to a post by Raymond Chen. Yes, the link is broken (because Microsoft has changed their blogging platform more times than I can to count), but you can hunt down the blog post again by using your favorite search engine with Raymond Chen Windows 95 RAM.

There (current link: https://devblogs.microsoft.com/oldnewthing/20030814-00/?p=42903), you will see that he starts with: "Windows 95 will fail to boot if you have more than around 480MB of memory".

Raymond explains in fair amount of detail why the limit exists - and you will notice it has nothing to do with caching. He also explains that the limit was not raised until Windows 98. Raymond doesn't mention any workaround for this limit, and as far as I know none exists.

Yes, that means there is a bit of a conflict between the solution implied by the Microsoft Q article and what Raymond says, but when such a conflict arises you do well by giving more credence to what Raymond has to say. He was part of the original implementation team for Windows 95 and a very well-respected expert. Microsoft's documentation quality is actually higher than most organization's, but that doesn't mean that some incomplete or misleading articles have not made it out over the years. As I understand it, many Microsoft "fix" articles are the result of a Microsoft support team solving a problem for one customer and documenting what they discovered. Unfortunately, sometimes they are actually documenting something that happened to work for the one customer's limited situation but doesn't work in general. Also, rarely does the solution get vetted by the engineers who actually worked on the application or OS.

If you really want Windows 95 on your computer, you probably have only two options. You could find a way to significantly reduce the amount of enabled memory on your computer (Some kind of BIOS switch? Remove the extra RAM?). A better solution is to switch to Windows 98 which was in every way a "better Windows 95 than Windows 95".

The fact that the computer runs both Windows 3.1 and also a more modern OS doesn't mean that it has to be able to run every OS in between. The Windows 95 architecture is significantly different from the one in Windows 3.1 (and even more different from the Windows 2 architecture).

  • 1
    the system.ini "easy fix" i used, was using the "MaxPhysPage=3B000" fix. this works for Windows 98, and after i did that, it stopped giving me memory errors, only the "Windows protection error" which after some research, i know its that the CPU is over 2.1GHz. but I did install the patch so im not too sure Sep 20 at 15:27
  • 2
    Thanks. You should always include those details in the main question, not in comments. Comments are meant to be ephemeral. In any case, it doesn't change the fact that Windows 95 cannot initialize with 1GB of RAM available as described in the article. Sep 20 at 15:45
  • yes, I edited the question including my specs, I can edit it again saying the RAM problem. but here is the thing. I know windows 95 is differerent greatly from Windows 98, but the system.ini change works on 98, plus, Windows 3.1 handles it just fine (then again, it uses it differently,) if you have any more ideas on the error, please let me know i really dont think its the RAM EDIT: you know, im just relizing know, ill add this to the question, im sorry i havent before, but right before the main bootscreen, i do get a message saying "invalid MSDOS.SYS file:winver=4.01" Sep 20 at 15:58

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