From: alexfrunews@gmail.com   
      
   On Monday, July 12, 2021 at 8:27:31 AM UTC-7, Rod Pemberton wrote:   
   > If you want to read about some of the problems transitioning to 32-bit,   
   > see the 68000 micro-procesor which had 24-bit addresses. Programmers   
   > found uses for those upper bits ... The 68000 series migrated to   
   > 32-bit addresses and couldn't execute older software.   
      
   They could've required bit 23 of the address to zero/sign-extend to   
   bits 24 through 31 in the original design to discourage tricks that hamper   
   compatibility. Like the "canonical addresses" on x86-64.   
      
   Or if there was page translation on the 68000 (looks like it was on the 68010),   
   they could've probably mapped addresses of 16M and greater onto the same   
   range as the ones below 16M, that is, having multiple aliases to the same RAM.   
      
   Alex   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)