Before you begin using the DDK, you need to update your copy of MASM to at least version 6.11c, and you will probably need to increase your environment space.
You need MASM version 6.11c to build drivers for Windows 95. After you install MASM version 6.11, you will need to copy the files from the \Masm611c\Bin directory on the CD-ROM to your MASM directory.
You should increase your environment space because the DDK, SDK, compiler, and assembler use additional environment space for storage of search paths. Add the following command to your Config.sys file (or change the line already there):
shell=c:\command.com /p /e:2048
This command gives you an environment of 2,048 bytes. If you receive out of environment space messages, you should increase the environment further.