Chapter 6 Notes

OSM Level - Operating System Machine

bulletISA Level instructions
bulletSystem calls interpreted
bulletVirtual Memory
bulletPaging - transparent to programmer - one big memory space
bulletMMU - memory management unit
bulletDemand paging vs. working set
bulletPage replacement
bulletLRU - least recently used
bulletFIFO - first in first out
bulletSegments
bulletCompletely independent address spaces, varying lengths may be dynamic. Simplifies the handling of growing and shrinking data structures
bulletTwo part address, segment # and entry point
bulletFacilitates sharing procedures or data between several programs
bulletDifferent segments can have different kinds of protection
bulletImplementation - external fragmentation
bulletBest Fit
bulletFirst Fit
bulletSwapping combined with paging

Virtual IO Instructions (pgs 429-335)

bulletFiles -> series of bytes
bulletLogical records (record I/O)

Example O.S.

bulletUltrasparc II - UNIX pgs. 446-449
bulletPentium II - Win NT pgs. 449-445