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List Info Thread: Re: PCL or PostScript
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Re: PCL or PostScript |
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List Info Thread: Re: PCL or PostScript
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ix.netcom.com>
On 10/02/2007 at 15:57 you wrote concerning
Re: [PageStreamSupport] PCL or PostScript
Hi Henry,
HB>> ...PCL is the rival of PostScript (according to
Wikipedia), so not
HB>> interchangeable.
HB>>
HB> I'm not really up on the topic, but if Wikipedia is
describing PCL as a
HB> "rival" of PostScript, they should choose a
better word or clarify
HB> themselves.
You are being excessively kind to Wikipedia. If the above is
how Wikipedia
describes PCL, then it is a clear indicator of how poor a
source "of 'reliable'
information" this 'pedia constitutes. In this
particular case, it would be the
author of the particular articile who should shoulder the
blame. Declaring PCL
(Printer Control Language) as "the rival of
Postscript" is an indelible mark of
ignorance.
HB> Historically, the two were rivals only in the sense
that
HB> they were rivals in /quality/ in the printers that
supported them back
HB> when computer printers were moving from the 9-pin,
dot matrix era where
HB> you got only the fonts built into the printer to the
present era of true
HB> translation of what you get on the screen to the
printed page.
Comparing PCL with PostScript is just plain ridiculous.
PostScript is a
programming language intended as "a page
description" language (roughly). To
quote briefly from the Red Book:
"
The PostScript language is a simple interpretive programming
language with
powerful graphics capabilities. Its primary application is
to describe the
appearance of text, graphical shapes, and sampled images on
printed or
displayed pages. A program in this language can communicate
a description of a
document from a composition system to a printing system or
control the
appearance of text and graphics on a display. The
description is high level and
device independent.
"
NOTICE: "device independent"!
PCL is intended for HP laser printers or printers which can
emulate a particular
variety of PCL. My old HP laserjet came with PCL 5, but PCL
6 is now availble.
I assume PCL 6 is a superset of PCL5, although I do not know
that. This
assumption is based on the fact that PCL 5 IS a superset of
PCL 4. I don't know
whether HP's inkjets use PCL .
HB> Someone correct me if I'm wrong, but PCL is a
Hewlett/Packard protocol
HB> used within their printers but popular enough to be
included as an
HB> option in other brands as well.
I'm not in a position "to correct you", but I
would agree with the above Henry.
HB> As far as I know, it's never been
HB> promoted as an independent tool for formatting
documents.
Correct.
HB> With
HB> PostScript you have an intermediate file which you
can open in an editor
HB> and see that it's a page description language which
can be modified
HB> directly—at least you might want to modify the header
information.
There is no "intermediate file."
A PostScript program is encoded in plain Ascii, hence any
idiot can modify any
PostScript program if they possess a simple text editor --
like ED! However,
changing a PostScript document without considerable
knowledge of the PostScript
language is about as sane as rewriting one of Beethoven's
symphonies and not
knowing what a quarter note is.
When a 'proper' PostScript program is sent to a PostScript
capable printer,
there is no translation process. The printer has "a
Postscript engine" within
it and that engine understands the PostScript language and
will transform
PostScript directives into appropriate printer commands for
the particular
printer. For example, I assume that "the PostScript
engine" within an HP laser
printer would be quite different from one within a Brother
laser printer,
assuming both were PostScript capable.
HB> To
HB> the best of my knowledge, you can't do that in PCL.
PCL is always in the
HB> printer directly or by emulation and there's no
intermediate file to
HB> deal with.
To the best of my knowledge, the above is false.
If you have an editor which will handle binary codes --
e.g., will recognize the
Escape character, and other "Control characters"
-- then you can edit a PCL
file. However, I don't know how you would get your hands on
the "PCL file" in
the first place. If you have the patience and knowledge of
PCL codes, you could
prepare a PCL document and then send it to your PCL equipped
printer for
printing. Although feasible, I cannot imagine anyone doing
that for 'ordinary'
printing.
HB> Many printers have it, although I doubt that most of
the
HB> cheap ones would these days. It could be useful if
you don't have the
HB> right printer driver for your particular printer.
"Interchangeable"
HB> isn't really quite the right word to describe the
relationship since
HB> there was never any attempt to promote PCL in that
way.
"Interchangeable" is an absurd choice of words.
PCL is useful amongst a class of HP laserjets. Say, I have
document Ex.PCL5
which was created to be sent directly to my old HP laserjet
4 which understands
PCL 5 but not PostScript. However, tomorrow I buy --
following in Bart's
footsteps -- an HP 2605dn colour laser printer. Now, the HP
2605dn understands
PCL 6, and -- I'm willing to bet -- PCL 5 too. Therefore, I
can send my
document Ex.PCL5 to the HP 2605dn and have it printed
WITHOUT having to use
some software program which would 'massage' the file Ex.PCL5
into a format
consistent with PCL 6. Hopefully, a PCL 5 doc is already
'consistent' with PCL
6. None of this has anything to do with PostScript.
Cheers Don (Green Dragon)
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