It's a (very late) pre-release of Microsoft Windows 1.01 from early September 1985.

Release dates: 
--------------

    Windows 1.01 - Premiere Edition - 1985-07-30
 >> Windows 1.01 - 1.xx/1.xy Edition - 1985-09-03
    Windows 1.01 - Final Edition - 1985-11-15

It's tagged with 1.xx/1.xy since this numbering most likely originated from the OEM (CompuData/Tulip from The Netherlands).

There is a disputed file on Disk05, WRITE.DAT. WRITE.EXE is missing, it seems the OEM didn't ship this by the release of this build.
It's important of note since previous fake versions of Windows 1.00/1.01 also came with a lonely WRITE.DAT file...