EROS is a persistent operating system targeted towards managing resources with great longevity. The system provides a persistent single level store supporting two fundamental object types: nodes and pages. All primary objects, including memory segments and protection domains, are constructed out of these fundamental objects, and inherit their persistence. EROS is a pure capability system: access to objects is provided exclusively through the invocation of kernel enforced, secure capabilities. This paper describes the EROS Abstract Machine and the mechanisms used to achieve efficient consistency management within the system. The implementation, including all primary objects, a low overhead checkpoint/migration subsystem, and an efficient interprocess communication mechanism, requires less than 64 Kbytes of supervisor code (prior to size tuning).