1024 CYL versus WD2010

[was-John McMillan]

If I recall correctly, two recent notes seemed to assert that
WD2010 chips were needed -- and I couldn't see why.

Eg:
In article <254 at gnosys.UUCP> gst at gnosys.UUCP (Gary S. Trujillo) writes:
>I recently discovered a Boston-area source (which does mail-order) for
>the Micropolis model 1355, which has a formatted capacity of 159 Mbytes
>(it's 170 Mbytes unformatted).  The drive has eight heads with 1024
					       ^^^^^^^^^^^      ####
>cylinders, so I'm assuming it wouldn't require the P5.1 upgrade, though
						    ^^^^^^^^^^^^
>it would need the WD2010 chip (right?).
		   ######	====== -- No, I don't think so.
:
:
** LET'S AGREE THAT AN ESDI DISK IS IN-APPROPRIATE:  I READ THAT NOTE! **
				    --------------

_MY_ question is:
	WHY does anyone think the WD2010 is necessary for <= 1024 CYL?
							     ^^^^^^^^
So far as _I_ know, the WD1010 will suffice for
		any ST-506 disk <= 1024 CYL. (*)

I'd have skipped the whole matter, but I think someone else made the
same assertion in another note.  Perhaps I've missed some key feature
of this chip I should know about...

(*) -- OK, some ST-506 are better than others, as another note mentioned.
	And some disks require a kick-start, or table bang:  it's NOT
	the 3B1 here, fellahs.

john mcmillan	-- att!mtunb!jcm