What ReadyNAS 600 revision do I have?
There are two revisions of the ReadyNAS 600 model line. Revision A has drives which load from the front of the unit, and connect to the system via SATA cables. It also uses a Compact Flash card to store the firmware. Revision B loads drives from the top (often called 600-TL). The drives directly connect to the system board. This model also has no Compact Flash card, and instead stores the firmware directly on the system board via NAND Flash.