floppy drive fifo

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From: Bela Lubkin <belal@caldera.com>
Subject: Re: We can't read from floppy on Pentium II, SCO Unix rel. 5.0.0b and 5.0.2
Date: Mon, 21 May 2001 00:30:49 GMT
References: <347AB355.6C35@scomat> <9711252213.aa10032@vagabond.armory.com> <19991226041408.C18387@pp5.progplus.com> 

On 1999-12-26, Robert Weiner wrote:

> OSR 5.0.0's /etc/conf/pack.d/fd/space.c has these variables:
>   int fd_enable_FIFO = 0;
>   int fd_FIFOthresh = 0;
> 
> but OSR 5.0.5's does not.  Can they be added to space.c under 5.0.5?
> 
> The 5.0.5 Driver.o does have the symbols, something defined them:
>   [Index]   Value      Size    Type  Bind  Other Shndx   Name
>   [125]   |       596|       0|NOTY |GLOB |0    |2      |fd_FIFOthresh
>   [126]   |       592|       0|NOTY |GLOB |0    |2      |fd_enable_FIFO
> 
> My problem is with a 5.25" 1.2Mb floppy under 5.0.5 on a dual Pentium III
> 500Mhz box (Tyan S1832DL).  3.5" floppys work fine.  The 5.25" floppy
> always has I/O errors as described below and in some TAs.
> (5.25" Drive is used only to convert old media.)
> 
> Does anyone know if a 5.25" Teac FD-55GFR has a FIFO?

He was replying to my message from 1997, so we have a nice every-two-
years posting rhythm going on this topic (well, I guess I'm a little
early):

> On Tue, Nov 25, 1997 at 10:13:53PM +0000, Bela Lubkin wrote:

Anyway, I'm sure his problem has long since been fixed, but I'll toss in
a word of explanation anyway.  Those FIFO variables in fd/space.c were a
kludge to cover up for the fact that the guy who first put FIFO support
into the floppy driver was too lazy to figure out how to autoconfigure
it.  That was later fixed.  If Robert was having I/O errors with his
5.25" floppy on OpenServer 5.0.5, it was probably because the drive
hardware was defective.

In particular, the question "Does anyone know if a 5.25" Teac FD-55GFR
has a FIFO?" is off-track.  The FIFO is in the floppy _controller_, not
the drive.  Thus, the fact that his 3.5" drive worked correctly almost
certainly meant that the FIFO was being auto-recognized correctly and
that the entire control and data path down from the kernel to the
hardware was working fine.  The 5.25" target hardware was busted.

So, my response at the time would have been: replace the drive.  Plus,
perhaps, a comment on the fact that floppy drives are among the least
reliable types of hardware I have had the displeasure to work with.
Over time, I find that the floppy drive on most machines becomes flaky
and eventually stops working.  If the failure rate on hard drives or
even CD-ROM drives was anywhere near as high, I doubt any of us would
still be using computers, we'd have given them up as a bad idea.  (Oh,
perhaps I'm wrong -- a similar number of years of experience with the
reliability of MicroSoft operating systems hasn't managed to sour the
general public on computers...)

>Bela<

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