Ah, well ok that especificases when you reference MS-DOS you refer to the operating system, one thing is the MS-DOS and quite another to the CMD, although it may seem like and DOS commands work, and allowed to run MS-DOS applications, CMD allows longer texts, is different in your case leaves you because you use Windows 7 must be 32bit, the Autoexec.nt only found in Windows NT class 32bit (WinNt, 2000, Xp , Vista, Win7, Win8 / 8.1) provided you have installed the NTVDM (Virtual Dos Machine New Tecnology) in Windows 64 (XP64, Vista64, Win7-64, Win8 / 8.1-64) does not exist to not support 8 and 16 bits I clarify for you do not know.
Technically the sentence you used kb16 sp is correct, I've tried, I have found an explanation for this change is applied in Vista, but I have tried in a VM Win8.1 32bit and it worked perfectly, the question is how I placed, because there are explanations make the change through the notebook, I found using the CMD itself.
I will explain how I did it.
1-Run CMD, open the Run with Win + R and type CMD then OK, it runs with Administrator permissions, or go to the Command Prompt icon and run it as Administrator, is valid both ways.
2-In the window type CMD and press Enter autoexec.nt edit, the edit will open, but it would be Notepad CMD (DOS)
3-Go to the end of the text, create a blank line and write sp kb16
4-With the mouse go to the Tools menu of the edit and display the File menu, click Save, then click Exit.
5-Write Exit in the Windows CMD and press Enter, closing the CMD.
We return to six-run CMD, type edit and press Enter, it will reopen the notice of CMD, test (one letter is infallible Ñ).
I do not know if the way you made as if you made it through the notepad of Windows, try it editing from CMD, of course it is advisable to degas prior modification.
As you rinse the operating system you use and is the CMD and not the operating system MS-DOS, so back to Win7, I changed the title to better compression, sorry for the inconvenience.
Greetings;)