The file hycom/ALL/README.ALL/README.ALL.1st :
"Typically almost all executables are created just once by editing
Make_all.src for the correct ARCH and then issuing the command
I.e. $ 'csh Make_all.com' in the directory "hycom/ALL/".
And : The file Make_all.src is already set to "amd64" for x86_64.