The PC Client directory contains Sybase Central for ASE 12.5
Alternatively, you can still use the old SQL Advantage supplied in ASE 11.x/12.0 to coonect to ASE 12.5
You have to copy these files from ASE 11.5/12.0 the Bin and Dll folder and keep it to some folder say C:\SQLAdv and then includle the path in Environment system Variable 'path ' i.e C:\SQLAdv \Bin:C:\SQLAdv \Dll
Now open the sybase central and see the utility you will find it there.
Or Open the C:\SQLAdv \Bin folder and double click to the "Sqladv.exe"