Microsoft's MASM 6.14 is included in the masm32 package.
To get MASM 6.14, download masm32V8.zip from:
http://www.masm32.com/ (2.98 MB)
Unzip and run install.exe. It creates masm32 directory. The MASM files (ml.exe and ml.err) are in the masm32/bin directory.
Do NOT use the linker link.exe (32 bit) in the masm32/bin directory. Use the linker version 5.60 to generate 16-bit DOS applications. You can get this from
http://download.microsoft.com/download/vc15/Update/1/WIN98/EN-US/Lnk563.exe (275 KB)
Execute lnk563.exe to extract link.exe file.
You need these three files (ml.exe, ml.err, and link.exe) to run the assembly programs. Copy these files into a directory and add it to your search path (i.e. modify your autoexec.bat file's SET PATH line by appending the directory path).
You can use MASM to assemble and link in a single step.
For example, to assemble and link ADDIGITS.ASM, use
ml addigits.asm io.obj
Ignore the END directive warning.
To assemble only (as in TASM), use /c option
ml /c addigits.asm
Then link using
link addigits io
Good luck!