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From: davidc@vlsisj.VLSI.COM (David Chapman)
Newsgroups: comp.unix.i386,comp.unix.xenix,comp.sources.wanted
Subject: Re: Fast parallel driver for Unix/Xenix AT?
Summary: could be a hardware problem
Message-ID: <15402@vlsisj.VLSI.COM>
Date: 28 Nov 89 03:08:36 GMT
References: <256ADBB5.19093@ateng.com> <289@marvin.moncam.co.uk> <522@romed.UUCP>
Reply-To: davidc@vlsisj.UUCP (David Chapman)
Organization: VLSI Technology Inc., San Jose, CA
Lines: 35

In article <522@romed.UUCP> pete@romed.UUCP (Pete Rourke) writes:
|In article <289@marvin.moncam.co.uk> emmo@moncam.co.uk (Dave Emmerson) writes:
|>In article <256ADBB5.19093@ateng.com>, chip@ateng.com (Chip Salzenberg) writes:
|>> [stuff omitted]
|>> know.  It's a crying shame to have slow printer output when it's the driver
|>> causing the slowdown.
|>
|>Forget it, the printer itself is usually the bottleneck, there's no point in
|>worrying about getting > 1k char/sec to a printer which can only output at
|> [stuff omitted]
|
|I am probably entering late in this discussion, but I have the same problem
|with the printer output being slow. I have a Compaq 386 portable running XENIX
|2.3.2 and it is terribly slow at printing on a HP Laserjet II. The same system
|has a DOS partition, and when printing from DOS the speed improves dramatically.Both DOS and XENIX are printing from Microsoft Word 5.  
|
|This would implicate that the driver was part of the speed problem.

One problem with IBM PC-class machines is that the parallel printer port
doesn't have hardware for interrupt-driven servicing.  As a result it must
be polled.  In a multi-tasking environment on a busy machine it might not
get enough opportunity to poll.  Under DOS the printer driver is attached
to the clock interrupt, guaranteeing plenty of polling opportunities.  My
guess is that XENIX doesn't do this; a printer driver would probably not
be "special" (i.e. part of the kernel) but would instead be a normal process.

It's conceivable that it is a "stupid software" problem, but I think it is
unlikely.  Can't you call your OS vendor?  (Yes, I know you can't do that
for DOS, but maybe SCO or Microsoft will treat you better if you've spent a
lot more money. :-)
-- 
		David Chapman

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