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In order to explain the use of these hardware features, we explain how the ECS system of CAL TSS might be re-implemented. The state of each object will be represented in one or more segments. A single data segment might suffice for some simple objects, e.g., a file with a single data block. More complicated objects would be represented by a capability segment with capabilities for subparts. A locked capability for the representing segment is then given to user programs. A user program will call the system with parameters in hardware registers. Upon entry, the system will pick up the appropriate keys and unlock each expected parameter. In one step, this will check for correct parameter type, sufficient access bits, correct unique name at the specified MOT index; and produces a segment descriptor for the representation of the object.

Paul McJones