source for WD1007WA2

[Karl Denninger]

In article <3607 at ddsw1.MCS.COM> nvk at ddsw1.MCS.COM (Norman Kohn) writes:
>In article <5343 at tekgvs.LABS.TEK.COM> keithe at tekgvs.LABS.TEK.COM (Keith Ericson) writes:
>>WD has (at least) two versions of their 1007 ESDI controller; one of
>>them is only capable of a 2:1 interleave and should be avoided if at
>>all possible.  The later version is alleged to be capable of 1:1
>>interleave but I haven't evaluated one to verify this.
>I've heard that the 1:1 is not yet available, but should be soon.
>I've also been told, however, that WD's ESDI card gives 1/35 fewer
>sectors than Adaptek's, presumably because it allocates one alternate
>sector per track (for bad sectors found at format time) and that this
>feature cannot be disabled.  Adaptek's is allegedly better for unix.

Not true.

The WD1007 has several set-ups available.  It supports 1:1 interleave, first
off.  Secondly, you have a choice of translation mode enabled or disabled,
and a choice of three (usually) translation settings.  There are some
catches though, which you need to be aware of:

If you turn OFF translation and the BIOS, you need an external format
program.  This is not normally a problem, and it will allow you to use the
full 35 sectors per track.  HOWEVER -- your operating system must be able to
deal with this, and map out the defects.  Many cannot do this right (386/ix
comes immediately to mind :-()

If the BIOS is enabled, you are normally running at 34 sectors per track,
with the 35th being set up as "sector 0".  The controller is smart enough to
reformat a track so that a defect (if it occurs) is in sector zero, thus
making it invisible.  This only works if there is ONE defect in a given
track.

The BIOS also has a mode to spoof the drive into looking like it has less
than 1024 cylinders, even when it does not.  This can be VERY useful if your
operating system will not install without an exact match in the ROM drive 
tables, as these tables will not go out beyond 1024 cyls.

Lastly, be aware that the BIOS sometimes decides to write to the CMOS memory
on the system.  This can cause problems with machines that have an "extended
CMOS" setup, allowing changes to things like shadow RAM and I/O speeds.
You'll know if this is happening because you'll get checksum errors in your
CMOS (grrrrr).  IF this happens, you will need to disable the onboard BIOS
completely, although you can do it AFTER formatting (providing your OS can
handle > 1024 cyl drives; Xenix can do this) and still get what appears to
be an error-free device.

>On the other hand, if unix 386 only allows a fixed number of bad sectors
>(64 in uport) and an entire track is bad somewhere, with large
>hard drives the table could fill up pretty quickly.

This is true; you can get around this by having what appears to be a "flaw
free" disk easily..... 

I LIKE this controller; it works great, and is very fast.  

Adaptec has been problematical for me in the past.  DTC, which also makes
ESDI boards, hasn't managed to get one here for evaluation yet, so I have no
idea what their boards are like.

--
Karl Denninger (karl at ddsw1.MCS.COM, <well-connected>!ddsw1!karl)
Public Access Data Line: [+1 312 566-8911], Voice: [+1 312 566-8910]
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