From: quadibloc@invalid.invalid   
      
   On Mon, 11 Aug 2025 10:27:08 -0700, Stephen Fuld wrote:   
      
   > Your goals, even if you meet them aren't particularly useful, e.g. being   
   > "nearly" plug compatible with S/360   
      
   > There are *far* simpler ways to accomplish what most people really want   
   > to do.   
      
   Being plug-compatible with System/360 is not among the goals of my ISA.   
   The term "plug-compatible" refers to... _plugs_, as one might guess.   
   Nothing in my ISA talks about stuff like USB ports, Centronics parallel   
   ports... or the kind of port IBM used to connect a 1403 printer to a   
   System/360 computer.   
      
   There are certainly far simpler ways to run System/360 code correctly.   
   One can just set a mode bit to enter System/360 emulation, for example.   
      
   What I'm doing with the Type V header is to provide a way to imitate the   
   behavior of a System/360 program after code conversion. So one could write   
   a special FORTRAN compiler to generate code using this header to allow a   
   FORTRAN program running on the Concertina II to deliver the same results   
   as on a System/360.   
      
   And this isn't simple because it's buried deep down in the instruction set   
   as an _afterthought_ within an ISA which is primarily designed to do the   
   same sort of work as one might do with an x86-64 chip or a PowerPC chip or   
   a SPARC chip even. And secondarily designed to be capable of   
   implementations which shine at whatever the TMS20C6000 shines at, or even   
   whatever, if anything, the Itanium was good for.   
      
   It may not, however, be lost on implementors that a full implementation of   
   the Type V header stuff ends up putting the needed circuitry on the die to   
   *provide* a very nice System/360 emulation or implementation, which they   
   might offer as an added feature not defined in the Concertina II   
   specification.   
      
   John Savard   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)