AutoCAD Release History
Shaan Hurley has always been my reference for AutoCAD history and has an excellent page on this. So the question came up the other day "What was the first version of AutoCAD for Windows". My memory told me it was Release 12, but I was not quite sure. A little searching turned up this document which confirms that R12c3 (Release 12, patch c3) was the first major release for Windows (see first comment below regarding R11 for Windows). Since Windows itself taxed most affordable computer systems back then, most people probably stayed on DOS, Solaris, or one of the other platforms for AutoCAD at that time.
If you have a DWG file and are not sure about its version, drop it into Notepad or some other ASCII/Hex editor and look at the first 6 bytes and compare to the table below.
|6 byte header||AutoCAD Version|
|AC1027||AutoCAD 2013, 2014|
|AC1021||AutoCAD 2007, 2008, 2009|
|AC1018||AutoCAD 2004, 2005, 2006|
|AC1015||AutoCAD 2000, 2000i, 2002|
|AC1014||AutoCAD Release 14|
|AC1013||AutoCAD Release 13|
|AC1009||AutoCAD Release 11, 12|
|AC1006||AutoCAD Release 10|
|AC1004||AutoCAD Release 9|
Below is a Release 13 installation floppy disc. You needed this to go along with the CD-ROM, also shown below.