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> Segmentation is really nice, and should have been carried on, IMO. Are you serious and are you talking about x86 memory segmentation? Honest question. As far
by weinzierl 7y ago
> Segmentation is really nice, and should have been carried on, IMO.
Are you serious and are you talking about x86 memory segmentation? Honest question. As far as I'm concerned thinking about CS, DS and ES still gives me shivers and I don't remember to ever have met anyone back then who loved segmentation. The only thing I hated more was the bit planes stuff on the graphics card...
- monocasa 7y agoThe 16-bit segments weren't great because you were forced to jump through all these hoops in order access the full addressable space. 32-bit segments that weren't crippled led to a lot of really interesting applications that weren't able to be replicated with what we have now. Hence why there's this gap of amd64 CPUs where there's no virtualization support in long mode but 32bit OSes could on the same chips.
- weinzierl 7y agoInteresting, I wasn't aware that you could use them in protected mode and they were 32-bits wide from the 386 on-wards. It also reminded me of something else: I think Tanenbaum discussed the advantages of the segmented memory model in his operating systems book, but I never paid attention because coming from the 16-bit word I immediately dismissed that idea. I might have to reread that chapter...
- Taniwha 7y agoIt's worse than that, you can set up 32-bit segments in 32-bit mode, then switch back to 16-bit mode and have them do vaguely sensible things .... This wasn't defined by Intel, but Windows went on to depend on this feature in order to boot (to access PCI) (I was once involved in an x86 clone project)
- EvanAnderson 7y agoFor anybody who is curious, this is colloquially referred-to as "unreal mode": https://en.m.wikipedia.org/wiki/Unreal_mode https://en.m.wikipedia.org/wiki/Unreal_mode