From: johnl@taugh.com   
      
   According to Scott Lurndal :   
   >>I'm pretty sure you'll find all of those in sort programs from the 1960s.   
   >>Sorting used more computer time than anything else so they put a great   
   >>deal of work into making it fast.   
   >   
   >Indeed, the sort subsystem on the Burroughs systems was, perhaps,   
   >even more important that the MCP itself to a lot of customers.   
   >   
   >Although large sorts in those days were done using magnetic tapes.   
   >   
   >(watching a large sort-merge running on a dozen 9-track drives   
   >was pretty impressive).   
      
   Yup. I suspect that the read backward feature on tape drives was invented to   
   speed up sorting, when someone realized that if you'd written a set of tapes,   
   you could read them backward and merge into the next set of tapes in reverse   
   order, repeat until done. You might need an extra pass at the end if the final   
   result was an even-numbered pass written in reverse order, but you still won   
   overall because you didn't have to rewind between all the intermediate passes.   
      
      
   --   
   Regards,   
   John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for   
   Dummies",   
   Please consider the environment before reading this e-mail. https://jl.ly   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)