I'd prefer it if we stayed on topic here... On Fri, Dec 6, 2019 at 3:15 PM Chris Angelico <ros...@gmail.com> wrote:
> On Sat, Dec 7, 2019 at 9:58 AM Greg Ewing <greg.ew...@canterbury.ac.nz> > wrote: > > > > On 7/12/19 2:54 am, Rhodri James wrote: > > > > > You've talked some about not making the 640k mistake > > > > I think it's a bit unfair to call it a "mistake". They had a 1MB > > address space limit to work with, and that was a reasonable place > > to put the division between RAM and display/IO space. If anything > > is to be criticised, it's Intel's decision to only add 4 more > > address bits when going from an 8-bit to a 16-bit architecture. > > > > And to construct a bizarre segmented system that means that 16 + 16 = > 20, thus making it very hard to improve on it later. If it hadn't been > for the overlapping segment idea, it would have been easy to go to 24 > address lines later, and eventually 32. But since the 16:16 segmented > system was built the way it was, every CPU afterwards had to remain > compatible with it. > > Do you know when support for the A20 gate was finally dropped? 2013. > Yes. THIS DECADE. If they'd decided to go for 32-bit addressing (even > with 20 address lines), it would have been far easier to improve on it > later. > > I'm sure there were good reasons for what they did (and hey, it did > mean TSRs could be fairly granular in their memory requirements), but > it's still a lesson to be learned from in not unnecessarily restrict > something that follows Moore's Law. > > ChrisA > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/SW5HDQ27KBNYFMWAIMPVCGLVLNGQVNOK/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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