From: james.harris.1@gmail.com   
      
   On 15/12/2022 01:12, Dan Cross wrote:   
   > In article ,   
   > James Harris   wrote:   
      
   ...   
      
   >> The Pentium Architecture and Programming Manual, Order Number 241430 says:   
   >>   
   >> "The 32-bit Intel architectures have different requirements for enabling   
   >> paging and switching to protected mode. The Intel386 processor requires   
   >> following steps 1 [jump] or 2 [identify mapping] above. The Intel486   
   >> processor requires following both steps 1 and 2 above. The Pentium   
   >> processor requires only step 2 but for upwards and downwards code   
   >> compatibility with the Intel386 and Intel486 processors, it is   
   >> recommended both steps 1 and 2 be taken."   
   >   
   > So now we're down to compatiblity with processors that are a   
   > quarter century obsolete. :-) Seriously, on a modern x86   
   > processor, you don't need the jmp after turning on paging.  It   
   > won't hurt anything should someone try and run this on an   
   > actual 386 or 486, but it is no longer required.   
      
   I would agree with you that it's been many years since the 386 and 486   
   were available new from Intel ... but they are far from obsolete. Even   
   now they are bought and sold second hand. Those who buy them presumably   
   do so not to have them sit on a shelf but run software on them. YMMV, of   
   course, but I cannot see an advantage in avoiding compatibility with   
   such older processors, especially as the JMP instruction is so easy to   
   include.   
      
      
   --   
   James Harris   
      
   --- SoupGate-Win32 v1.05   
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