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   comp.arch      Apparently more than just beeps & boops      131,241 messages   

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   Message 129,519 of 131,241   
   John Savard to All   
   Shuffling the Headers Around   
   27 Aug 25 13:35:50   
   
   From: quadibloc@invalid.invalid   
      
   Some additional tweaks have been made to the Concertina II instruction set.   
      
   The Type I header has had one capability removed from it in order to make   
   room for the Type Ia header.   
      
   Now, in addition to a zero-overhead header which has an operate   
   instruction built in, zero-overhead headers which have a memory-reference   
   instruction built in are also available.   
      
   The format of those memory-reference instructions is extremely limited,   
   but at least it makes it _possible_ to have pseudo-immediates in a   
   sequence where a memory-reference instruction goes in the leading spot of   
   the block involved. One just has to allocate registers correctly to get   
   this zero reference.   
      
   Also, a while back, the ability to have 64-bit instructions in code   
   without block headers was removed. It wasn't intneded to actually remove   
   this from the ISA, but at the time, significant changes and re-   
   organizations of the block headers were taking place, and I didn't want to   
   keep these instructions updated to correspond.   
      
   Now that this phase is over, they have been put back in.   
      
   These changes, and some recent ones preceding them, have been aimed at   
   enhancing either the ability to do without headers, or, if headers are   
   needed, to increase the options to avoid their overhead cost if possible.   
      
   Block headers are needed, because I can't figure out how to do pseudo-   
   immediates without them, but as they are painful, I'm trying to both   
   minimize their overhead and reduce the number of cases where there is need   
   for them as much as I can.   
      
   John Savard   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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