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.   
      
   Note that at this time most programs were commercial.  Simple   
   business rule is that people who have more money can pay   
   more, so you should set higher price for them.  But how   
   to recognize folks with more money?  One simple trick is   
   to look what processor they have, if it is 386 than   
   owner spend notrivial money on processor/computer so   
   can pay more for software.  So software house would have   
   "low end" 8086 version and more expensive 386 version.   
   386 version may be faster due to 32-bit instructions   
   and there is more place for features but it would not   
   run on 8086.  Put it differently: why work hard and   
   get less money, when you can work less and earn more?   
      
   Anyway, you have your own desires, but most people moved   
   on and are happy to consider 8086 just as history, not   
   as something to be a serious developement target.   
      
   --   
                                 Waldek Hebisch   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)