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Date:      Sat, 13 Sep 1997 20:07:04 -0700 (PDT)
From:      Alex <garbanzo@hooked.net>
To:        current@freebsd.org
Subject:   Re: Do *you* have problems with floppies?
Message-ID:  <Pine.BSF.3.96.970913192416.2357A-100000@zippy.dyn.ml.org>
Resent-Message-ID: <Pine.BSF.3.96.970913215638.2847D@zippy.dyn.ml.org>
In-Reply-To: <199709132104.OAA20111@usr08.primenet.com>

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On Sat, 13 Sep 1997, Terry Lambert wrote:

> Only the Intel 82077AA has FIFO's (the 82078 des to, but I don't
> know what the heck it returns for a version ID -- anyone have one?).

A quick web search revealed that Linux will identify four different
"breeds" of 82078s (linux/drivers/block/floppy.c).
 
> All other FDC chips with FIFO's are unprobeable, unless they
> return a version ID.
> 
> When you boot, you will see one of:
> 
> fdc0: NEC 765
> fdc0: Intel 82077
> fdc0: NEC 72065B
> fdc0: unknown IC type ff
> 
> ...or *whatever* two digit hex value, other than  0x80, 0x81, or 0x90.
> 
> The current driver code does not enable the FIFO.  It would need to
> have detected as an 82077, and then use the Configure command (0x13)
> to clear bit 5 of command byte 2.  It would set bits 0-3 to enable
> a 16 byte threshold.  Then it would need to use the Lock FIFO command
> (0x94) to save the FIFO state across software resets.
> 
> Then there would be additional code changes, as necessary, on top of
> that.

- alex





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