From: muta...@gmail.com   
      
   On Tuesday, October 11, 2022 at 9:18:40 AM UTC+8, Joe Monk wrote:   
   > > The instruction would refuse to change the shift   
   > > value on an 8086. On an 80286 it would only   
   > > need to support a shift value up   
   > > to 8.   
   > >   
   > > Almost no extra circuitry would be required.   
   > >   
   > Real mode on a 286 is confined to 4 bits (limited to 1MB). You need extra   
   circuitry in the MMU if you want to do anything more.   
   > > An 80386 should support a shift of 16.   
   > > Almost no extra circuitry would be required.   
   > Yep. Same answer as for 286. Extra MMU circuitry to do any more than 4 bits   
   in real mode.   
   > > The cost is close to nothing because there   
   > > are no extra address lines.   
   > Its not the address lines. Its the circuitry in the MMU to handle the larger   
   shifts.   
      
   Yes, I agree. A very small amount of extra   
   circuitry would need to be added to the   
   80286 or a modern x64, to support   
   enhanced real mode with flexible shifts.   
      
   --- SoupGate-Win32 v1.05   
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