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From: jt19840@tut.fi (Tuomi Jyrki Juhani)
Newsgroups: comp.sys.ibm.pc
Subject: Interleaving with WD1006V-SR2?
Keywords: Disk controllers, interleaving, WD1006
Message-ID: <2127@tutor.tut.fi>
Date: 3 Oct 89 13:55:05 GMT
Reply-To: jt19840@tut.fi
Organization: Tampere University of Technology, Finland
Lines: 30

I've been reading a lot of good words on the WD1006V lately.  However,
I have a question about the interleave factor with this board.  I'm
running a 386/AT clone (C&T chipset) with a WD1006V-SR2 and a Seagate
65MB disk.  The disk has been formatted using the on-board BIOS setup-
routine (WD1006V-SR1/2 MR1/2 SETUP REV. 2.0).

Spintest reports a
transfer rate of 399 360 BYTES/s with 2 revolutions/track, i.e.
interleave 2:1.  CORETEST 2.8 reports a transfer rate of 437 to 438
Kbytes/s.  HDTST128 reports an interleave of 2:1.  I have done a non-
destructive re-format (using HDTST128) to change the interleave to 1:1.
However, when I check the interleave after re-formatting, it is still
reported as 2:1 and xfer rates are the same as before.  Toggling the on-board
cache enable/disable jumper has no detectable effect whatsoever.

I am somewhat confused.  The xfer rates are quite near to theoretical
rate achievable using 2:1 interleave with 26 sectors/track (even if one
doesn't trust the interleave factors reported by various programs).
With a disk controller having a track buffer, I would expect that the
on-board formatting routine would always use 1:1 interleaving, but
the xfer rates don't quite support that conclusion.
And, the formatting routine does not give the user an option to set the
interleave.

If you have any information that would explain these numbers, I would
be most grateful to hear (read) it.

Jyrki Tuomi
Tampere University of Technology, Finland
Internet:  jt19840@tut.fi    UUCP:  ..mcvax!tut!jt19840