What is B? And is it alwys 256?

Also, isn't there a way to use these numbers to find the speed and the cpacity of a hard drive?

C/H/S or Cylinder/Head/Sector is an address to a specific place certain hard drives (Cylinder/Head/Sector is used pre-Windows 95 and in some *-nix systems), (Cylinder/Side/Sector is used in most machines today). You may find this site helpful:
http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/admin-primer/s1-storage-data-addr.html

And 'B' is usually an abbreviation for 'byte', and I byte is eight bits, or binary digits.

As for speed, it usually has nothing to do with any of the above. However, hard drive size can be calculated using these numbers.

thanks for the link. Very informative.