wd1003 floppy ports - test-drb@ccmp.vtda.org

11 May 2006

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Subject: Re: wd1003 floppy ports
   From: "Chuck Guzis" <cclist at sydex.com>
   Date: Tue, 09 May 2006 23:04:18 -0700
     To: cctalk at classiccmp.org

On 5/9/2006 at 8:06 PM dwight elvey wrote:>Hi

 I want to know what the WD1003WA2 does with the
3F7 port.
Most controllers use this port to control clock speeds. On the
WD1003WA2, there is a jumper that is stated to be used to select
360 RPM drives or 300 RPM drives. I'm trying to determine if
the controller will do FM. One many older controllers that do support
FM, the clock rate is set by sending 3 to port 3F7. Does 3F7 do
anything on the WD1003WA2? If so, what. 
Well, my spec sheet for the WA2 says that it uses a 765 with a 16C92
support device and supports data rates of 500, 300, 250 and 125 Kbps.  If
this is anything like the standard AT controller, then setting port 3F7 to
3 will enable the 125 Kbps clock.  Does it support FM?  The spec sheet
doesn't say.  As far as the jumper goes, IIRC, it's used to denote a
dual-speed (360 high-density, 300 low-denisty) 1.2MB drive.

However, one of the later AT controllers, like the 1003WA4, the 1003RA2 or
the 1006 series uses the 37C65 controller which definitely supports FM
encoding.

Cheers,
Chuck

The short answer is yes.  The longer answer is you have to program the 
correct clock and tell the FDC to do FM not MFM (cammand bit).  Also 
you have to specify (the command) HLT, LUT and STEP times as needed.

Allison