[Simh] anyone know how to convert/translate turbo pascal to vax pascal?
Clem Cole
clemc at ccc.com
Thu Feb 8 12:44:14 EST 2018
Yup - traditional Pascal (lack of) portability due to the report having
been silent. Associating files with file descriptors could never be
agreed so ISO never defined how to do. Every OS does it differently.
Since Wirth was silent on it, if they picked one scheme over another the
Pascal committee was favoring that implementation [Kernighan may have even
pointed this out in his paper they wrote after writing the software tools
in Pascal - Why Pascal is Not My Favorite Programming Language
<http://wiki.lazarus.freepascal.org/Why_Pascal_is_Not_My_Favorite_Programming_Language>
].**
Go google the two document I mentioned previously and it should be a fairly
simply change. Look up file I/O and then read how VMS implemented the
association of name.
I'm now going by memory, but a number of Pascal's did that in the reset()
function. A number created a new function as Turbo did (assign() in this
case, but I think open() was used by a couple of other Pascals. I think a
couple of other pass it in via the Program function and style other that
supported separate libraries (usually called units) did it other ways still.
For grins, in the late 1970s at an HP/Tektronix 'Hatfield/McCoy' style
party - in those days HP in particular was Basic happy and Tek was mostly
Pascal. We counted over 25 different incompatible 'HP Basic'
implementations, and over 10 different Tek Pascals.
These are just the sorts of things you need the Turbo Pascal manual in one
had if that is were you are coming from and in this case the VMS Pascal
manual in the other. Look up assign() in the first and the read how
perform the same action in the other.
Good Luck,
Clem
** IMHO: This is a good example of where C 'beat' Pascal - the I/O was
defined by UNIX and when it came time to create a standard, C mostly kept
the UNIX semantics and was able to keep many/most of the OS-ism from other
systems out.
ᐧ
On Thu, Feb 8, 2018 at 12:21 PM, Dan Gahlinger <dgahling at hotmail.com> wrote:
> so here you go, a simple file compare I wrote using "freepascal" (
> freepascal.org) and I've done what I can to convert it to vms pascal
> but it doesn't compile.
>
> code:
> Program fcomp(input,output);
> var
> f, g, h : text;
> s, t, u : varying [255] of char;
> c, d : char;
> i : integer;
> begin
> s := 'first.txt';
> t := 'second.txt';
> u := 'output.txt';
> i := 0;
> assign(f,s);
> reset(f);
> assign(g,t);
> reset(g);
> assign(h,u);
> rewrite(h);
> while (not(eof(f))) do
> begin
> read(f,c);
> read(g,d);
> i := i + 1;
> if (c <> d) then
> writeln(h,i,' = 1:[',c,']/',ord(c),' 2:[',d,']/',ord(d));
> end;
> close(f);
> close(g);
> close(h);
> end.
>
> errors:
> pas fcomp.pas
> 00016 0 1 assign(f,s);
> 1
> %PASCAL-E-UNDECLID, (1) Undeclared identifier ASSIGN
> at line number 16 in file DUA1:[DAN]FCOMP.PAS;4
> %PASCAL-E-ENDDIAGS, PASCAL completed with 1 diagnostic
>
> ------------------------------
> *From:* Clem Cole <clemc at ccc.com>
> *Sent:* February 8, 2018 10:58 AM
> *To:* Dan Gahlinger
> *Cc:* Gary Lee Phillips; Tim Shoppa; simh at trailing-edge.com
> *Subject:* Re: [Simh] anyone know how to convert/translate turbo pascal
> to vax pascal?
>
> Dan,
>
> As others have said something smells wrong here. It's true the original
> '71 report from Wirth did not defined I/O and '72 revised report only
> defined write. By the time of the Jensen & Wirth book from Springer-Verlag
> in the mid-late '70s writeln is there. And by the time of the first
> standard efforts @ IEEE and ANSI it very much in the language. I do have
> an old copy ANSI/IEEE770X3.97-1983 "American National Standard Pascal
> Computer Programming Language" which on page 93 (Section 6.9.3) defines the
> required standard Pascal function writeln:
>
> *6.9.4 The Procedure Writeln.*
>
> The syntax of the parameter list of writeln shall be:
>
> writeln-parameter-list = [ "(" ( file-variable | write-parameter )
> | "," write-parameter | ")" ] .
>
> *Writeln* shall only be applied to textfiles. If the file-variable or the
> writeln-parameter-list is omitted, the procedure shall be applied to the
> required textfile output.
>
>
> From a quick search on the HP web site (http://h41379.www4.hpe.com/
> commercial/pascal/pascal_index.html ) I found reference to the SPD and
> the site says: :
>
> HP Pascal (formerly known as Compaq Pascal and DEC Pascal) runs on OpenVMS
> for VAX systems, OpenVMS for AlphaServer systems, and OpenVMS for Integrity
> servers. With HP Pascal, your source code investment is not only protected,
> it is extended.
>
> HP Pascal supports code compatible with either level of the ISO
> specification, meets Federal Information Processing Standard Publications
> (FIPS-109) requirements, and supports many features from the Extended
> Pascal Standard. HP Pascal has a solid reputation as a robust,
> production-quality, high-performance compiler. It is a full compiler, not
> an interpretive one. Tightly integrated wit
>
> While I do not have FIPS 109 on my system, FIPS was based on ANSI/IEEE770X3.97,
> and I do have a copy of the an old DEC pascal manual so I'm 100% sure
> writeln is there. I also believe that Turbo Pascal was developed after the ANSI/IEEE770X3.97
> was published so the Turbo extension to writeln and any VMS ones should be
> able to puzzled out.
>
> Here is a pointer to Pascal for OpenVMS - User Manual Order Number:
> AA-PXSND-TK
> <https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c04619822>
> This may give you hints.
>
> That said, I have a PDF of the VMS Pascal Reference, but lord knows where
> it came from; probably my time at DEC. I have to believe its on bitsavers
> or the like. But when I look on page 9-67, Section 9.8.26 defines the
> WRITELN procedure as defined in the standard with the one DEC extension of
> supporting that last optional parameter to be: [, ERROR := error-recovery]
> where error-recovery is defined as the action to be taken when an error
> occurs.
>
> As other have said maybe its something silly from file format conversion
> like <CR><LF> processing as VMS record oriented I/O is different than
> DOS/Windows. But I suspect you are running into a difference in how I/O
> is declared and bound to files on the disk. My experience with a number
> of different Pascal compilers 'back in the day' was this was an area for
> wide variation. This is what I would look up in the HP/Compaq/DEC user
> manuals I just pointed you too. I suspect that the 'VMS Pascal Language'
> manual should help you through the DEC variant, so google is your friend to
> try find a PDF. With that open and a Turbo Pascal manual I think you'll be
> fine (and if you cannot find a Turbo manual, I have to believe the
> freepascal.org docs will get you a long way since they claim to be 100%
> Turbo Pascal and Delphi compatible).
>
> BTW: One other though/place where Pascal I/O can differ is character
> sets, although I don't think it a problem because PCs and Vaxen never had
> this issue, if you read any the reports or "Jensen and Wirth" you will
> notice that Pascal was defined for a 6-bit byte on a CDC-6600 system (SCOPE
> was the OS IIRC). As I have said elsewhere, a 6-bit character was not
> unusual on earlier systems -> today, we can thank Fred Brooks for the 8-bit
> byte (Gene Amdahl wanted it to be 6 bits but Brooks kicked him out of his
> office until he had something that could easily be handled by SW - *i.e*.
> a power of 2, which Amdahl thought was wasteful for the HW).
>
> Anyway, characters can be an issue when moving Pascal code because
> original Pascal was defined with some CDC isms and in those days, CDC had
> as number of different character sets. I note that if look at the ANSI
> standard you'll noted the definition of all identifiers is just the lower
> case [english] chars a-z for letters, the traditional digits 0-9 and very
> limited number of special-symbols ( + - * / = < > [ ] . , : ' | ( ) ).
> They do say:
>
> The representation of any letter (upper-case or lower-case, differences of
> font, *etc*.) occurring anywhere outside of a character-string (see
> 6.1.7) shall be insignificant in that occurrence to the meaning of the
> program.
>
> Because of the '6-bit ness' of some systems, the standard even provides
> for alternative tokens to do things like square braces to (. and .) or
> vertical bar to @ [and I think may allow ^ to be used for same IIRC].
>
> Also remember that DEC manuals tended to show the identifiers in upper
> case (go figure). And since both Vaxen and Intel processors (*i.e. *VMS
> Pascal and Turbo Pascal) support at least 7-bit ASCII fitting into an 8 bit
> character, and DEC added support for other special symbols such as dollar
> $, but I have to believe the problem is not in character set.
>
> Best wishes,
> Clem
>
> ᐧ
>
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