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From: rick@pcrat.UUCP (Rick Richardson)
Newsgroups: comp.laser-printers
Subject: Re: Parallel Port under SCO 3.2
Keywords: parallel SCO3.2 386 graphics
Message-ID: <9008061927.AA10100@crayola.cs.UMD.EDU>
Date: 23 Jul 90 03:03:28 GMT
References: <9006190355.AA22086@crayola.cs.UMD.EDU> <9007120320.AA28424@crayola.cs.UMD.EDU> <9007200324.AA07449@crayola.cs.UMD.EDU>
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In article <9007200324.AA07449@crayola.cs.UMD.EDU> bill@bilver.UUCP writes:
>In article <9007120320.AA28424@crayola.cs.UMD.EDU> terry@EESUN1.EECE.KSU.EDU (Terry Hull) writes:

>>The parallel port does not support 8 bit characters under SCO Unix. 
>>The serial ports do, but obviously they are slower driving the printer.   

>Now so obviously in my experience.   I have a site that has an HP II a found
>that putting in a cheap convertor/buffer, I was able to get better performance
>out of an intelligent serial board (Anvil), than I could through the parallel
>port.   

Provided the parallel device driver in your UNIX is up to the task,
you should be able to move up to around 4900 *bytes*/second thru the
parallel port into the LJII.  That would be the equivalent of 49000
bits/second thru a serial port, except that the LJII only goes up to
19200 on the serial port.*

I say "up to 4900 bytes/second", because the content of the data stream
has a lot to do with how fast the LJII is willing to accept data.
300 DPI bitmaps move a lot faster than plain text and positioning
commands.  You might only get 1500 bytes/second for text and
positioning commands.  Of course, you don't need as much speed for
text, since the print engine speed (8PPM) dominates when printing text.
Remember, a page of text might be 5-10K of data, but a bitmap page can
be up to 1 meg of data.

* Measured on 16 Mhz 80386 running INTERACTIVE 386/ix 2.0.2 and
  no-name clone parallel port.  Measured by queuing up 1 page of
  data using "lp" command with printer off-line; put printer
  on-line and measure the elapsed time until print engine turns on.

-Rick

-- 
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