[sebhc] Z37 Calibration

Barry Watzman Watzman at neo.rr.com
Thu Mar 31 13:50:44 CST 2005

Lee, I'm not aware of any 3.5" drives that ever run at anything other than

As to 5.25" high density drives, some change speed, but in other systems,
the speed is locked down and the "change" is made by changing the bit rate
into and out of the controller -- not using the "standard" bit rates.

-----Original Message-----
From: sebhc-bounces at sebhc.org [mailto:sebhc-bounces at sebhc.org] On Behalf Of
Lee Hart
Sent: Thursday, March 31, 2005 4:43 PM
To: sebhc at sebhc.org
Subject: Re: [sebhc] Z37 Calibration

Dwight wrote:
>>  You need to use a 360K drive. I suspect that the 5.25 you have
>> is a 1.2M and it won't work with the 3.5. These are 1.44M.

Peter Shkabara wrote:
> Actually, the H37 controller will work just fine with 3.5 inch
> drives, but they need to be in the 720k mode. I don't know if
> some newer 3.5 drives include this mode or not, but I would
> suspect that they should to read the older format disks.

The situation is complicated. Some 1.2meg 5.25" drives can operate as
720k (what the H89 calls 800k) drives. To do so, they need a switchble
rotational speed. But since this feature isn't used in PCs, it is often
left out.

Some 1.44meg 3.5" drives can operate as 720k (H89 800k format, but on a
3.5" disk). Again, this requires a switchable rotational speed. And
again, this feature isn't used in recent PCs, and so is left out of most

So, you have to know if the drives you have are switchable or not; and
if they are, you need to set the jumpers or program the I/O lines to set
the correct speed.

If you have a 1.44meg 3.5" or 1.2meg 5.25" drive that is NOT switchable,
the only way to use it with the H89 is with a Magnolia or CDR controller
board, configured to treat these as if they were 8" 1.2meg drives.
If you would not be forgotten
When your body's dead and rotten
Then write of great deeds worth the reading
Or do the great deeds worth repeating
	-- Ben Franklin, Poor Richard's Almanac
Lee A. Hart  814 8th Ave N  Sartell MN 56377  leeahart_at_earthlink.net

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