antispam@math.uni.wroc.pl wrote:   
   > muta...@gmail.com  wrote:   
   > > On Saturday, July 17, 2021 at 6:13:03 AM UTC+10, anti...@math.uni.wroc.pl   
   wrote:   
   > >   
   > > > Another things: you write as you invented soemthing. Various   
   > > > segmentation schemes were studied and in 1985 it was well   
   > > > known that technically you could use different segment   
   > > > shift. But it was also known that such machine would   
   > > > have no advantages, so nobody tried to make it.   
   > >   
   > > Ok, so just for the record.   
   > >   
   > > It was well-known by 1985 that at least SOME 8086 programs   
   > > (in all memory models, even huge) could be run on the 80386   
   > > and have a 512 MiB address space, but absolutely no-one saw   
   > > any advantage to 512 MiB vs 1 MiB and would prefer that   
   > > ALL their 8086 programs be restricted to 1 MiB for a number   
   > > of years and then completely fail.   
   >   
   > Sorry, you can not repeat correctly.  It was well-known that   
   > you could run some 8086 programs on 286 and 386 and use more   
   > memory (up to 16 M on 286, up to 512 M on 80386).  It was   
   > also well understood that arbitrary segments origins on 286   
   > and 386 gave more possibilities than your "segment shift",   
   > so nobody was intereded in machine using shift bigger than 4.   
   > Concerning using more memory: it was known what to do and   
   > there were ready made solutions (DOS extenders).  AFAICS   
   > there was little interest in making "universal binaries",   
   > that is one which worked on 8086 in 1M and on better   
   > processors using more memory.   
   >   
   > Concerning "no one": there was a lot of various developements,   
   > most is now forgotten.  It is possible (even resonably likely)   
   > that some obscure programs tried to use more memory and   
   > be compatible with 8086.  But one can be resonably sure   
   > that nobody wrote programs targeting your PDOS.  And   
   > using 512 M in program capable of running on 8086 with   
   > 1 M was in little (maybe no demand) simply because in 1990   
   > machine with 512 M memory would be extremaly expensive   
   > special-purpose machine, and later in general ability to   
   > run on 8086 was of limited use.   
      
   Little correction and addition: there was period when Windows   
   supported 8086, 286 and 386.  Windows applications were   
   supposed to run on all those machine.  So there is body of   
   application that run on 8086 with ability to use more memory.   
   You prefer DOS, so probably this is of no iterest to you.   
   But this shows that it was known how to do this and it got   
   some use.  OTOH I never saw Windows running on 8086.   
   I saw guy running Windows on 1 M 286.  Guy was satisfied   
   that it run at all, my opinion was that it was unusably   
   slow.  I remember that when Miscrisoft annouced that   
   Windows no longer supports 8086, there was a comment   
   that progrmmers are very satisfied, trying to make   
   programs run on 8086 was pain with little reward.   
      
   --   
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