[Info-vax] VMS on a PC

[John Reagan]

"Alan Winston - SSRL Central Computing" <winston at SSRL.SLAC.STANFORD.EDU> 
wrote in message news:00A85C81.E779B5E0 at SSRL.SLAC.STANFORD.EDU...

>
> Wasn't there an 8086 port of Bliss for Windows NT?  (I think it's even on
> the freeware someplace.)
>

Yes.  However, it was truely X86-only.  Knew nothing about the 64-bit 
extensions to the architecture (additional registers, additional 
instructions).  Didn't generate ELF object files.  Conformed to the Windows 
calling conventios.  And was only a subset of BLISS.  Features not used by 
GEM or Visual Fortran (or Rdb) were not implemented.  Beyond that, the 
X86-variant of GEM also didn't include features used by languages other than 
BLISS or C.  For instance, all the packed decimal stuff used by COBOL or 
varying-length strings of Pascal was just stubbed-off.

As I've said before, Macro-32 is the real bottleneck.  Besides redoing about 
1/3 of the compiler (the same 1/3 redone from Alpha to I64), you have to 
come up with some mapping of the registers used by the current code base 
(code currently assumes registers R0-R31 are available in some fashion). 
Try mapping that onto the 16 registers in the X86-64 architecture and get 
that to work with linkages to C/BLISS; exception handling; unwinding; etc.

John