Evolution of Memory Protection and Virtual Memory

Paul_Koning at Dell.com Paul_Koning at Dell.com
Mon Oct 6 08:58:57 CDT 2008


A very nice reference is "Computer Structures -- readings and examples" by Bell and Newell (McGraw-Hill, 1971).  There's a section in it about "Virtual-address space and memory mapping" (page 77-80).  It describes a whole lot of schemes and lists early instances.  For example, there is a scheme that has protection but not relocation (IBM 1800 -- per word, and SDS Sigma-2 -- per page).  There are schemes with a base address and length (PDP-6, CDC 6000) or two of those (PDP-10).  And there are page mapping schemes (Atlas, CDC 3500) and segment descriptor table ones (Burroughs 5500).  All those are early to mid 1960s.

	paul





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