[Simh] DECWRITE backup set pt 2

[Jeremy Begg]

Hi Timothe and Gary,

I'm the other person who replied to Gary's questions and I think I can
clarify some issues.

You are correct, X11 Display Postscript was removed from VMS in version 7.3
for various reasons, I think foremost among them was that Adobe no longer
wanted to support it because they were busy with PDF.  (They took the
lessons from PostScript and created PDF to be better for both screen and
print.)

The first step to get DECwrite running on VMS 7.3 or later is to get the
XDPS shareable images from an earlier version.  I can't recall if the
upgrade from 7.2 to 7.3 deleted them or left them in place, but in either
case you will need the file SYS$SHARE:XDPS$DPSLIBSHR.EXE from the VMS 7.2
distribution, and maybe XDPS$DPSBINDINGSSHR.EXE and XDPS$DPSCLIENTSHR.EXE
also.  Those files are used by any application which incorporates DPS
functionality, such as DECwrite.

However, DECwrite is quite happy to work with an X11 server that does *not*
have the Display PostScript Extension.  This is because DPS is only used for
displaying "Encapsulated PostScript" (EPS) docuemnts.  EPS was the mechanism
created to allow PostScript to be embedded in multi-media document.  If you
don't need to display an EPS element you won't need DPS.  (I have DECwrite
running on a headless VAXstation 4000-96 using my Linux workstation as the
X11 server, which doesn't have the DPS extension).

DECwrite does not use DPS to do screen formatting, unless it's got an EPS
element in the document.  If you're creating your own documents you can
embedded other graphics formats in the document -- anything supported by
DEC's Compound Document Architecture model (other than PostScript).

Hope this helps.

Regards,

	Jeremy Begg


>Thinking about DPS some more (was never a mainline thing for me), a few
>memories surfaced:

>You can go back to VMS 7.2 & either run  there or more the library to 7.3.

>But that's just the client side.  The DPS interpreter goes in the X
>server (where the display is);
>its an 'X extension'.

>I don't know that there's a current X server that still includes it.  It
>is complicated, ugly and
>Adobe licensing was involved.

>There may be a ghostscript based extension that will do it, but you'll
>have to hunt down a
>version of the server that supports/can be built with it.  It looks like
>most of the servers
>dropped DPS support quite a while ago.

>Alternatively, VMS 7.2 with a local graphics card should work, as
>DECwindows of that time
>included the DPS extension in its server.

>SimH has some graphics card support - but I've never played with it, so
>I don't know what
>luck you'll have that way.

>You're going to have the same issue with Alpha; that's not an escape clause.

>DPS was a clever idea - basically postscript was the way to get dots
>formed on a laser printer
>in a typographically sane fashion.  But it was based on the idea that
>one composed one
>page at a time.  DPS extended the engine so you could have multiple
>active composing contexts
>(e.g. one per window!).  I think it also allowed for composing partial
>pages (clipping to the
>visible portion).

>The clever part was that this meant that you  could have a real WYSIWUG
>(what you saw is
>exactly what you got:-) editor.  Unlike now, when what I see in a brower
>never prints the
>same - because of the layers of different print renderers that are
>attached to devices.

>DEC licensed the interpreter from Adobe (as it did for the one in the
>LPS series
>printers).  I don't think we had a big role in its development; Steve
>Jobs apparently
>did when he was in exile at NeXT.

>I think the complexity and performance killed DPS.  Also, applications
>(e.g. DECwrite)
>use it via X11, which windoze displaced.  It came fairly late in the
>evolution of X.
>So there wasn't a huge application base.  PDF is the logical successor.

>This from my recollection of conversations with the hardcopy and
>workstation groups,
>and a little archaeology.  As I say, this wasn't a mainline issue for
>me; I touched on it
>in terms of how to extract text for assistive technologies.  So this may
>not be 100%
>accurate.