1. A digital data processing device, comprising: a memory, said memory containing a segment table, said segment table having a plurality of segment table entries corresponding to respective segments in a first address space, each segment table entry containing pre-fetch data identifying a plurality of sub-units of the corresponding segment as pre-fetch candidates; at least one processor; at least one structure for temporarily storing data from said memory in a location more accessible to said processor; and a pre-fetch engine, said pre-fetch engine performing at least one pre-fetch action, said at least one pre-fetch action comprising pre-fetching selective data with respect to a sub-unit of said plurality of sub-units of a segment from said memory into said at least one structure for temporarily storing data, said pre-fetch engine selecting said selective data for pre-fetching using said pre-fetch data in said segment table.