Hi,
Starting with ASE 15.7 SP100 they pulled Sybase Central from PC-Client. Now with ASE 16.0 there is not PC-Client download. What you would do instead is get the SAP SDK (SAP Software Developers Kit) for ASE.
If yoiu want the older version with Sybase Central you can look through the older or base install of ASE 15.7 and look for the PC-Client download. You can also do a search for 51025144, this was PC-Client from ASE 15.7 ESD#1. The client components are older though.
So after that I would suggest getting the more current SDK 15.7 SP126 and install it on top of the PC-Client.
If you don't need Sybase Central get the SDK 16.0 PL00 SP02 (note they pulled the oledb and put DBISQL (Interactive SQL) in 16.0 series)
Aslo please note that starting in the 15.5 series and above all the EBFs are complete install packages so no base is needed.
Thanks,
Dawn Kim