> > The story goes that Andrew Tannenbaum (Comp Sci professor and > > creator of MINIX, which few can dispute was an inspiration for Linux) > > criticized Linux as "out of date", being monolithic. > > See > http://www.oreilly.com/catalog/opensources/book/appa.html > Enjoyable reading!
"Most older operating systems are monolithic, that is, the whole operating system is a single a.out file that runs in 'kernel mode.' This binary contains the process management, memory management, file system and the rest. Examples of such systems are UNIX, MS-DOS, VMS, MVS, OS/360, MULTICS, and many more." I can't comment on his other qualifications, but I find 'monolithic' to be a very poor characterisation of MVS at all levels. If you take Supervisor State to be equivalent to "kernel mode" then he's way off base - very little of MVS runs that way. Key 0 may be a better approximation, but even that isn't so much. People have been mixing'n'matching bits of MVS releases, VSAM, DFSMS, JES for years. True, you don't have quite the same flexibility that you inevitably get with a open source system, but nevertheless ... -- Phil Payne http://www.isham-research.com +44 7785 302 803 +49 173 6242039
