Path: utzoo!news-server.csri.toronto.edu!rutgers!mit-eddie!bloom-beacon!eru!hagbard!sunic!isgate!krafla!adamd
From: adamd@rhi.hi.is (Adam David)
Newsgroups: comp.sys.atari.st
Subject: Re: 1.44mb drives
Message-ID: <2886@krafla.rhi.hi.is>
Date: 12 Mar 91 16:37:16 GMT
References: <1991Feb28.085205.28239@phoenix.pub.uu.oz.au> <1991Mar06.123439.20676@actrix.gen.nz>
Organization: University of Iceland
Lines: 31

In <1991Mar06.123439.20676@actrix.gen.nz> Roger.Sheppard@bbs.actrix.gen.nz writes:

>The other way is the one that the Germans came out with is to Change the
>Clock to the WD 1770 controller IC, but this can be hit or miss as the
>IC is not ment to run with a 16 Meg HZ clock,

The WD1772 controller has to be the more recent type for it to work properly.
All recent ST's should have the right chip. The suffix on the older chip is -01
and on the newer one is -02. I think the date-stamps are 1985 and 1987. The
simplest way is to let the density sense line select the clock speed. The clock
to the controller should be deglitched during the speed change. If you want to
format DD disks to HD (doubtful practice) then a little more circuitry is
required, probably involving the sound chip.
It would be nice to change the step rate for the drives to suit the disk each
time a disk is changed.
I don't have it up and running yet, so I can't post the details. If no-one beats
me to it I'll get it done sometime.

Meanwhiles, could someone point out which pins carry these signals:

a) disk-in-drive
b) density-sense
c) .....anything else not on older DD drives?

oh, and while I'm at it: 

Does anyone know whether the WD1772 can handle 1024-byte sectors?
If so then it should be possible to format 1848k onto a HD disk.
--
Adam David.
adamd@rhi.hi.is