You evidently did not read my reply above, the paging you are talking about has nothing to do with disk, it is a (windows) OS feature. Paging in the '51 world refer to pages of ROM or RAM of 64k each with access control as described above. The '51 is not a PC substitute it is a microCONTROLLER, not a microPROCESSOR. The '51 is great for doing one thing and doing it well, beyond that it is usually not the best choice.

Have fun

Erik