Path: utzoo!attcan!uunet!lll-winken!ames!coherent!dplatt
From: dplatt@coherent.com (Dave Platt)
Newsgroups: comp.sys.mac
Subject: Re: A few Deskjet+ observations
Message-ID: <25319@coherent.com>
Date: 22 May 89 17:34:12 GMT
References: <10452@orstcs.CS.ORST.EDU> <780003@hpvcfs1.HP.COM> <2042@ccnysci.UUCP>
Reply-To: dplatt@coherent.com (Dave Platt)
Organization: Coherent Thought Inc., Palo Alto CA
Lines: 63

In article <2042@ccnysci.UUCP> alexis@ccnysci.UUCP (Alexis Rosen) writes:

> OK. I am just about ready to get a DeskJet to play with (might be a good
> printer for some clients). The big question is: Do any of the drivers out
> there work well with a serial/parallel converter? I can't see why not, but
> they might not make use of the higher speed (depends on how fast they can
> build the page). I'd like to use MacPrint with a parallel cable, if it will
> work well. I've got a Mac II with a cache, so there's plenty of CPU for the
> driver to use. I primarily print text, but some of my clients do a lot of
> graphics and page layout.

None of the drivers with which I'm familiar are configured to send data
at > 19200 bps.  Pushing serial data into a serial/parallel converter
at 19200 bps would probably not speed up a DeskJet.  It might speed up
a DeskJet Plus somewhat because the Plus uses DMA to gobble data over
the parallel interface, rather than polling the parallel port
periodically (and thus there might be some extra CPU cycles left for
doing the printing).  I would not expect a major speedup, though.

You might be able to take an off-the-shelf driver (MacPrint or DataPak,
for example) and patch it so that it would spit bits at 38400 bps.  If
you have a serial/parallel converter that works at this speed, you could
probably get better speed out of the DeskJet Plus.

You might also be able to take an off-the-shelf driver and patch it to
work with the Hurdler-CPI or some other Centronics-compatible driver
card for the Mac II.  This would be more work, though... the _Control
calls are substantially different.

> I guess none of this will matter in another nine months. System 7 will make
> these kinds of printers much more attractive to the masses.

Yes, these printers will be much more attractive once the new Print Shop
architecture hits the street.  The issue of getting large amounts of
rasterized data down into the printer will remain... 19200 bits/sec just
doesn't cut it.

Also, based on word I've received from a couple of sources, you should
probably not consider purchasing a DeskJet or a Plus for use with a Mac
for the next several weeks.  The details I have are sketchy, but they
lead me to believe that HP is going to be announcing a DeskJet model
which is customized for the Mac.  Its price is said to be the same as
that of a DeskJet Plus.  I was told by one user (who actually has an
order pending for one, overseas!) that it comes with a Mac driver, has a
Mac-specific ROM, and has an AppleTalk interface.  I was told by another
knowledgeable person that "this isn't quite right", but that I'll
recognize the announcement when I see it.

Actually, if there were one thing that HP could do to the DeskJet to
make it more attractive for use with the Mac, I think it would be to
substitute a SCSI interface for the Centronics parallel port (and, of
course, provide a software driver that could access the SCSI channel).
This technology has already been proven, with the LaserWriter IIsc and
the Personal Laser Printer.  A SCSI interface would quite effectively
eliminate the data-transfer channel as the bottleneck;  the printer's
speed would be limited by its print mechanism and/or by the speed with
which the Mac could rasterize the data.

-- 
Dave Platt    FIDONET:  Dave Platt on 1:204/444        VOICE: (415) 493-8805
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