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Date:      Sat, 11 May 2002 21:48:55 +0200
From:      Joerg Wunsch <j@uriah.heep.sax.de>
To:        "M. Warner Losh" <imp@village.org>
Cc:        brian@Awfulhak.org, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject:   Re: cvs commit: src/sys/isa fd.c fdreg.h
Message-ID:  <20020511214855.G91528@uriah.heep.sax.de>
In-Reply-To: <20020511.111210.41215654.imp@village.org>; from imp@village.org on Sat, May 11, 2002 at 11:12:10AM -0600
References:  <joerg@FreeBSD.org> <200205110015.g4B0F8nA006576@hak.lan.Awfulhak.org> <20020511082352.E91528@uriah.heep.sax.de> <20020511.111210.41215654.imp@village.org>

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As M. Warner Losh wrote:

> : (The man page for DELAY(9) doesn't mention any restriction
> : either.)
> 
> DELAY is always safe to use.

That was my impression now, too.

>  However, it is highly undesireable to
> use it for large values if !cold.

The value is 1. :)

There's an outer spin loop around the DELAY(1) that waits for a
certain bit pattern in the FDC main status register to appear.
Normally, the bit pattern should appear within a few microseconds at
most.  This is as undesirable as any PIO data transfer, but
unavoidable for the archaic underlying floppy controller hardware.

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)

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