Does anyone know the family of typeface the old Microsoft logo belongs to?
Suggested fonts
Franklin Gothic Suggested by Tomás Silcher
Microsoft Sans Serif Suggested by fukingklein
Arial Black Suggested by StefanusHosea
Zurich Black Suggested by mcdude64 
Microsoft and 95 are not Arial Black, looks like a thinner version of Arial. I don't think it's true Helvetica because Microsoft didn't have the rights to it I think, I might be wrong. So Arial is substitute for it, just like Times New Roman is for original Times font.
MS Sans Serif
Edited on Jun 14, 2014 at 10:28 by drf
ARE YOU SERIOUS GUYS? ITS FRANKLIN GOTHIC, IT COMES FROM OFFICE TOO
All of the text is Franklin Gothic, just different types.
Windows text is Franklin Gothic ATF Wide
AdrianR said 
Microsoft and 95 are not Arial Black, looks like a thinner version of Arial. I don't think it's true Helvetica because Microsoft didn't have the rights to it I think, I might be wrong. So Arial is substitute for it, just like Times New Roman is for original Times font.
It's FG
franklin gothic heavy italic looks similar to the WINDOWS text
Zurich std black is the one that’s probably used on the WINDOWS text
For the Microsoft and 95 text it is Franklin Gothic Book, for the Windows text it is Franklin Gothic Heavy. You don't need to download anything because it already is installed by default. (On Windows)
Microsoft and 95 are not Franklin Gothic Heavy, looks like a thinner version of Franklin Gothic. I don't think it's true Helvetica because Microsoft didn't have the rights to it I think, I might be wrong. So Franklin Gothic is substitute for it, just like Times New Roman is for original Times font.
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