Changing the Windows 95 logo


What you should know before reading this:

To animate the logo you created, you should know, how Palette animation works and you should be able to use a Hex-Editor.


Introduction:

There are different full-screen bitmaps in Windows 95, so there are different files for them. The startup logo is embedded in the file c:\io.sys. If you are using an extended version of Windows 95 (for example "Plus!") then you probably have a (hidden) file called c:\logo.sys. This file has a sys-extension but is a normal bmp-file. To find out, if it really is the startup logo, open it in Paint, it should work. The logo-bitmap in io.sys is on every Windows 95 system but the logo.sys-file exists just in non-standard versions. If both are present (a valid logo-bitmap in logo.sys and another one in io.sys), then the logo.sys-bitmap is displayed. For Details about how the "logo-display-mechanism" during the booting works, see section booting - pseudo code.
There are two other full-screen bitmaps: the one that says 'Please wait while your computer shuts down' (c:\windows\logow.sys) and the other one that tells you that it is now safe to turn off the computer (c:\windows\logos.sys). Sometimes there also is the bitmap available for the screen that you see when you start Windows 95 the first time (c:\windows\logo1st.sys). All three of them are normal .bmp-files with a sys-extension. They all have to be in a special format: width 320, height 400, colors 256.
Some programs store their full-screen bitmaps the same way (bmp file with sys-extension, format: 320x400x256) . For example Norton AntiVirus uses the two files c:\windows\nlogow.sys and c:\windows\nlogos.sys. If you have another program that stores its logos this way please contact me. I'll add a note to this page.


How to change the logo:

Maybe you want to restore the original logo later, so make a backup of the logo.sys-file. Then you will have to create a bitmap with the format 320x400x256. Note that the bitmap must be exactly this format to be displayed. - An alternative to creating your own bitmap is to go to the XrX Animated Logo Collection. There are a lot of logos to download for free. - Then you save the bitmap you have created/downloaded as "c:\logo.sys". When you now reboot the system, your logo is displayed instead of the default logo.


Animation during booting:

The standard logo includes an animation (the line at the bottom). This animation is a simple Palette Animation (Colorcycling) which starts at a certain palette entry and ends at the last(255th) palette entry. To use animation in your own logo-bitmap, you need to use an image-editing program that allows you to edit the palette manually (MS Paint doesn't let you do that). When modifying the palette, you have to place the entries which you want to animate at the end of the palette (including the last entry). Then you have to modify the bitmap-file in a hex-editor. You need to specify the palette index at which the colorcycling starts. You have to change the following bytes:
Offset: hex 32 - This byte must contain the first palette-entry you want to animate
Offset: hex 33 - must be set to zero.
If you have done all this properly, the animation will start automatically during the booting. The colorcycling runs from the higher palette indexes to the lower, for example: if the lowest animated palette entry is at index 250: 251 becomes 250, 252 becomes 251, 253 becomes 252 and so on.
View Example


"logo-display-mechanism" - Pseudo Code:

This is what I found out with experimenting a little bit. I don't know wether it is complete or the if-conditions are in the correct order but this way it seems to be okay.
if (line "Logo=0" in section '[Options]' of 'c:\msdos.sys' exists)
    don't display a logo
else
    if ('logo.sys' exists)
        if (logo.sys contains a valid(320x400x256) bitmap)
            display the logo.sys-bitmap
        else
            don't display a logo
    else
        display the io.sys-bitmap
As you can see you can prevent that the logo is displayed if you add the line "Logo=0" to the '[Options]' section of the file 'c:\msdos.sys'. Another way to prevent that a logo is displayed is to create an empty 'logo.sys' (actually, the file could contain any data but an 320x400x256 bitmap). This way the "logo-display-mechanism" would end at the "don't display a logo' in line 8 (because logo.sys doesn't contain a valid (320x400x256) bitmap). If you do not want the system to display a logo, prevent it using one of the methods metioned above, but do not delete 'io.sys'!. The file 'io.sys' contains data (beside the logo) which is absolutely necessary to run Windows 95.

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Copyright 1998 Stefan Hetzl. If you have questions or comments or have discovered an error, send mail to [email protected]. You may forward this document or publish it on your webpage as long as you don't change it and leave this notice at the end.