From: mparker@adobe.com (Mike Parker)
Newsgroups: comp.periphs.printers,comp.dcom.fax
Subject: Re: New Compaq PS printer/fax
Date: 14 Sep 92 18:03:18 GMT
Organization: Adobe Systems Incorporated, Mountain View

In article <1992Sep12.101822.29631@digibd.com> rick@digibd.com (Rick Richardson) writes:
>Give us some details!  Like:
>
>1)	The printer doesn't know whether a PS file can be sent to
>	the far end until it actually calls the far end machine.
>	If the machine turns out to not be a PS-fax, then it must
>	rasterize the pages to send them.  But, in general, a PS
>	program can take an arbitrarily long time to compute.  Does
>	the printer attempt to rasterize the pages on-the-fly? 

If the printer was told to send the job as a PS file transmission (the
host drivers have a phone book feature to help you keep track of who's
got PS fax machines and who hasn't) and we call and the remote machine
rejects PS file transmission, then we hang up right away and rasterize
the job.  We call back when we're ready with the raster.  When this happens
the phone log shows both calls one with a failure termination "callee rejected
PS file transmission" and one with a successful termination.

> What
>	happens if a page takes longer to rasterize than T.30 allows?
>	Or does the printer abort the call once it finds out it has
>	to rasterize, and then rasterize all the pages before making
>	a second attempt?  If this is the way it works, I would expect
>	that the host software must cooperate somehow, since you may
>	need an arbitrarily large amount of mass storage to store the
>	page images for the second attempt.

The host does not have to cooperate, but...  We must be able to store the
entire PS source file and still have room to fall back to raster if
necessary.  With a disk this is easy, with a michine with minimal RAM
some PS files are too big to be sent via PS file transmission.

As for storing pages etc.  This is wher emuch of the work went.  We rasterize
and compress and store pages until we reach a limit set by the software.  If
we haven't seen the end of the job, we place the phone call and then we
race the phone transmission.  If we lose the race, we append a trailer sheet
that says how much we've sent, who it's for, and that there's more to follow.
When we get a bunch of pages ready we call again prepend a cover that says this
is part of a previous job, X pages were sent in pervious transmissions, this
will be page X+1 and who the fax is for.  Normally, we win the race and never
get into this cute multiple call deal, one can easily design a pathological
file that places a phone call for every page in the fax.
>
>2)	What extensions to PS and PCL5 are made to allow host software
>	to specify fax mode destinations?

The PS extensions are too much to go into here.  We use the Level 2
setpagedevice command to set the output device to (Fax) and we build
a FaxOptions dictionary with all of the other information.  Thus:

<< /OutputDevice (FAX)
   /FaxOptions  <<
   /DialCallee (T4155551212) >>
>> setpagedevice
/Helvetica 12 selectfont
100 100 moveto
(Hello World!) show showpage

Would send Hello World to the 415 area code information operator.

There will be a new revision of the redbook supplement available any day now
with complete details.

We did not make the fax option work for PCL 5 files.
>
>3)	When recieving a FAX, are provisions made to allow the image
>	and/or PS file to be accessed by the host computer?  Or is
>	just printing allowed?

Not yet, get your specific feature requests in while there's still time....

>
>-Rick

mike

Repeated Disclaimer:  I'm not Adobe's fax spokesperson, I just like it so
much I have to talk about it.