https://techdifferences.com/difference-between-paging-and-segmentation-in-os.html
how does paging solve the problem of external fragments?
https://www.quora.com/How-external-fragmentation-is-possible-in-memory-management-using-Segmentation-scheme-in-OS
https://www.quora.com/What-is-fragmentation-internal-and-external-in-context-of-memory-management