DOS commands - Which are they ?

Could you help me to know the DOS commands that are not in windows help ?
Commands like making list of directories, splitting and joinning files, and so on. I search for them in the internet but found nothing.
As I use Win98, they are very useful.

list dirs: dir/B/S/A😁 c:\ (works on xp altleast)

split how/where? lines?

join: type a.txt>>b.txt

random links:

http://www.microsoft.com/resources/d....mspx?mfr=true
http://www.microsoft.com/technet/arc....mspx?mfr=true

BTW, this is a forum for the NSIS installer