S2VSPD.MEM -- SFTOVX Software Description
October, 1983





1.0  PRELIMINARY SOFTWARE DESCRIPTION

SFTOVX consists of a series of  APL  functions  designed  to
assist the APL-SF programmer in moving existing applications
from APL-SF V2 to VAX APL V1.1 or later.  The  migration  of
APL  workspaces  and data files from APLSF to VAX APL occurs
through text files.

MIGRATE, an APLSF function, builds a  batch  control  stream
which  then  executes  APL  functions that create text files
from APL files.  MIGRATE interacts with the user to find out
what   should  be  transported  and  prompts  the  user  for
filenames.  MIGRATE also  allows  the  user  to  specify  an
optional  filter  workspace  (containing  functions  such as
FILTER, ASFILTER, and DAFILTER) which  allows  the  user  to
modify  the  file before it is transported.  Files which can
be transferred include workspaces, and /AS, /IS, /DA and /BS
data files.

The  DRIVER  function  transfers  workspaces,  the  ASDRIVER
function  transfers  /AS  data  files, the DADRIVER function
transfers /DA data files and so on.  These driver functions,
invoked  by  a  batch  stream,  dump the workspaces and data
files as input  scripts  into  text  files  which  are  then
transferred by the user's own methods to the VAX.  Then they
are used by VAX APL as )INPUT files.

DRIVER  transports  variables,  system  variables,   channel
assignments, workspace identifications, groups, and unlocked
functions within APLSF workspaces as text to the VAX.  While
the   text   file   is   being  made,  DRIVER  examines  the
user-defined functions and performs  source  transformations
that  minimize  the  incompatibilities between APLSF and VAX
APL.

SUBMIT is a VAX APL function that  handles  the  text  files
that have been moved by the user.  SUBMIT interacts with the
user and builds a VMS command file that, when run indirectly
or  in  batch,  executes  VAX  APL  for  each  input  script
specified  by  the  user.   When  these  input  scripts  are
processed by means of VAX APL, a workspace or a data file is
created on the VAX.  These created files  are  the  migrated
images of their counterparts on TOPS-20.

Note that SFTOVX is a general tool which can be overlaid  by
the  user's  software in certain instances (for example, the
FILTER function).
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2.0  INCOMPATIBILITES

Incompatibilities do exist between APLSF and VAX  APL.   The
SFTOVX  functions  minimize  these incompatabilities in most
circumstances.  However, not all  incompatibilities  can  be
handled.  Some of the incompatabilities are listed below:

      o  Escape mode does not exist in VAX APL.

      o  Tabs in data and in files remain as tabs.  They are
         not converted to spaces in VAX APL.

      o  .Z@ is not recognized by VAX APL as  the  character
         underscored delta.

      o  In APLSF, .RU is a "U" with the  feet  pointing  to
         the  right;  .LU is a "U" with the feet pointing to
         the left.  In VAX APL, .RU is a "U" with  the  feet
         pointing to the left and .LU is a "U" with the feet
         pointing  to  the  right  (in  other   words,   the
         directions  of  the feet are opposite what they are
         in APLSF).  SFTOVX outputs the "U"  with  the  feet
         pointing to the right as "left U" (.LU) and the "U"
         with the feet pointing to the  left  as  "right  U"
         (.RU).   The  APL graphic from APLSF is the same as
         the APL graphic inside VAX APL.

      o  Dyadic $ is  not  supported  in  VAX  APL.   SFTOVX
         converts a $ primitive function to .BXFMT.

      o  Monadic .EN, .DE and .OM are not supported  in  VAX
         APL.   SFTOVX converts the primitive functions .EN,
         .DE, and .OM  to  the  user-defined  (DEC-provided)
         functions  .LD.USEN,  .LD.USDE,  and .LD.USOM which
         simulate the behavior under APLSF.

      o  A negative number raised to a non-integer power  by
         means of dyadic * is an error in VAX APL;  it gives
         an answer in APLSF.

      o  Output from .FM format is different in VAX APL.

      o  I-beams don't exist on the  VAX.   SFTOVX  replaces
         the  primitive  function  .IB  with .LD.USIB, which
         simulates most of the documented I-beams  and  none
         of the undocumented ones.

      o  .BXASCII is  not  supported  in  VAX  APL.   SFTOVX
         replaces   .BXASCII   with   a   niladic   function
         .LD.USASCII, which returns 128 VAX APL .BXAV  codes
         that resemble ASCII.

      o  .BXAV is  different  in  VAX  APL  than  in  APLSF.
         SFTOVX  replaces  .BXAV  with  a  niladic  function
         .LD.USAV, which returns 512  VAX  APL  .BXAV  codes
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         that resemble .BXAV in APLSF.

      o  Several system commands in APLSF  are  not  in  VAX
         APL.

      o  Some functions are quiet in  VAX  APL  but  not  in
         APLSF.

      o  .BXGAG values in APLSF are reversed in VAX APL.




3.0  REQUIRED SOFTWARE

APL-SF V2 and VAX APL V1.1



4.0  SOFTWARE INSTALLATION

CUSTOMER  INSTALLED  --  SFTOVX  is   a   software   product
engineered to be installed by the customer.



5.0  SUPPORT CATEGORY

CUSTOMER SUPPORTED



6.0  WARRANTY

NONE

THIS SOFTWARE  PRODUCT  IS  PROVIDED  "AS  IS"  WITHOUT  ANY
WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED.