4 ms·
Intel did you use that term to describe segmented addressing, at least in the 286 manual [1]: ""In Protected Virtual Address Mode, the 80286 provides an advanc
by rep_lodsb 4y ago
Intel did you use that term to describe segmented addressing, at least in the 286 manual [1]:
""In Protected Virtual Address Mode, the 80286 provides an advanced
architecture that retains substantial compatibility with the 8086 and other
processors in the 8086 family.""
""In Protected Mode, application programs deal exclusively with virtual
addresses; programs have no access whatsoever to the actual physical
addresses generated by the processor. As discussed in Chapter 2, an address
is specified by a program in terms of two components: (1) a 16-bit
effective address offset that determines the displacement, in bytes, of a
location within a segment; and (2) a 16-bit segment selector that uniquely
references a particular segment.""
[1] https://ragestorm.net/downloads/286intel.txt https://ragestorm.net/downloads/286intel.txt
- anyfoo 4y agoYou're right, I searched wrong in my 386 manual. So apparently they did call it virtual addressing. I'm still not sure if I like calling that an "MMU". To me, an MMU acts on every memory access. But at the end of the day, who cares what I think what words mean. :) The critical distinction to me is that segmentation is not much more than, effectively, an indexed addressing mode, where the base is the segment base that has been loaded into the descriptor cache when the segment register was loaded. Nothing happens at the time of actually accessing memory, except for the limit check.