For example, external memory may be an SDRAM and control pins may include such signals as clock enable (???CKE???), chip select (???CSA#??? and ???CSB#???) for selecting a particular external memory chip from a plurality of chips, write enable (???WEA??? and ???WEB???), and address signals (???MA??? and ???BA???) for rows, columns, and banks in external memory. [0044] Reference DLL 510 includes a