VMS Help PASCAL, /ARCHITECTURE=keyword D=/ARCH=GENERIC  *Conan The Librarian (sorry for the slow response - running on an old VAX)

                                   OpenVMS Alpha only

 Specifies the lowest version of the Alpha architecture where this
 code  will  run,  which  can  allow the compiler to generate more
 efficient code, with the tradeoff that code may not run on  older
 systems, unlike the /OPTIMIZE=TUNE qualifier.

 All Alpha processors implement a core set of instructions and, in
 some  cases,  the  following  extensions:   BWX  (byte- and word-
 manipulation instructions)  and  MAX  (multimedia  instructions).
 (The Alpha Architecture Reference Manual describes the extensions
 in detail.)

 The keyword specified with the /ARCHITECTURE qualifier determines
 which  instructions  the  compiler can generate, and which coding
 rules it must follow:

    GENERIC
      Generate instructions that are appropriate for all Alpha
      processors. This option is the default, and is equivalent to
      /ARCH=EV4.

    HOST
      Generate instructions for the processor that the compiler is
      running on (for example, EV56 instructions on an EV56 processor,
      EV4 instructions on an EV4 processor, and so on).

    EV4
      Generate instructions for the EV4 processor (21064, 20164A,
      21066, and 21068 chips).

      Applications compiled with this option will not incur any
      emulation overhead on any Alpha processor.

    EV5
      Generate instructions for the EV5 processor (some 21164 chips).
      (Note that the EV5 and EV56 processors both have the same chip
      number - 21164.)

      Applications compiled with this option will not incur any
      emulation overhead on any Alpha processor.

    EV56
      Generate instructions for EV56 processors (some 21164 chips).

      This option permits the compiler to generate any EV4 instruction,
      plus any instructions contained in the BWX extension.

      Applications compiled with this option may incur emulation
      overhead on EV4 and EV5 processors.

    PCA56
      Generate instructions for PCA56 processors (21164PC chips).

      This option permits the compiler to generate any EV4 instruction,
      plus any instructions contained in the BWX and MAX extensions.
      However, Compaq Pascal does not generate any of the instructions in
      the MAX (multimedia) extension to the Alpha architecture.

      Applications compiled with this option may incur emulation
      overhead on EV4 and EV5 processors.

    EV6
      Generate instructions for EV6 processors (21264 chips).

      This option permits the compiler to generate any EV4 instruction,
      any instruction contained in the BWX and MAX extensions, plus any
      instructions added for the EV6 chip.  These new instructions include
      a floating-point square root instruction (SQRT),
      integer/floating-point register transfer instructions, and additional
      instructions to identify extensions and processor groups.

      Applications compiled with this option may incur emulation
      overhead on EV4, EV5, EV56, and PCA56 processors.

    EV67
      Generate instructions for EV67 processors (21264A chips).

      This option permits the compiler to generate any EV6 instruction,
      plus the new bit count instructions (CTLZ, CTPOP, and CTTZ).
      However, Compaq Pascal does not currently generate any of the
      new bit count instructions so EV67 is essentially identical to EV6.

      Applications compiled with this option may incur emulation
      overhead on EV4, EV5, EV56, and PCA56 processors.

 Beginning with OpenVMS Alpha V7.1 and continuing with  subsequent
 versions,  the operating system includes an instruction emulator.
 This capability allows any Alpha  chip  to  execute  and  produce
 correct results from Alpha instructions - even if the some of the
 instructions are not implemented on the chip.  Applications using
 emulated   instructions   will   run  correctly,  but  may  incur
 significant emulation overhead at run time.   Emulation  for  the
 BWX  (byte  and  word) instructions was included in OpenVMS Alpha
 V7.1.    Emulation   for   the   floating-point   square    root,
 integer/floating-point   register   transfer,   and   bit   count
 instructions will be included in a version of OpenVMS Alpha after
 V7.2.