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From: adamd@rhi.hi.is (Adam David)
Newsgroups: comp.sys.atari.st.tech
Subject: Problems/Questions about Chinon HD drives.
Message-ID: <2623@krafla.rhi.hi.is>
Date: 14 Jan 91 21:58:43 GMT
Organization: University of Iceland
Lines: 75

I have twin Chinon FX357 drives connected up to my 1040STF with TOS 1.2
Both drives are on the same flatcable and they are configured as drives
0 and 1 by setting the jumpers. The flatcable is not twisted (which would
exchange DS0/DS1 for two DS0 drives) so the setup should work perfectly, but
drive A: (slightly further away on the flatcable) only just works when cold, and
refuses to read correct data from disks when warm unless the other drive is
disconnected. Each drive works perfectly well in isolation from the other.
It is enough to remove the power from drive B: to restore full working order
to drive A: , even when running hot. What is going on here? Do I have to
terminate the drive chain (there is 2.5 cm of flatcable between the drives,
less than 25 cm of flatcable between drive B: and the drive connector on the ST,
and Spectre GCR injects into the 14-pin DIN connector)? Everything works just 
fine (including Macintosh disks) except after the first few minutes when both
drives are connected. The drives are 5-Volt only types so they could be putting
too much of a strain on the power supply I suppose. What is the expected power
consumption of Hypercache + one extra drive? 
(BTW these are "intelligent" drives that only spin when a disk is in them).

Can anyone help with these problems?

It's a pity that these drives have caused problems with installation, and that
other people have had various problems with these drives, because there is no
other 3.5" floppy drive as robust & reliable as these Chinons once the possible 
difficulties of installation are over.

Now for the questions:

(1)

I caught the tail end of the "Media change problem" thread a while back.
Did anyone find a way of fixing these drives (or fixing TOS) in order to solve
this one? The problem as I see it is as follows:
The drive as shipped (and connected by all 34 pins to the ST) does not recognise
a disk change event unless the disk is write protected. "Normal" Atari drives
under Spectre flag a disk change if the disk is write enabled, but not when the
write-tab is open. Here's where it gets really weird ...
Spectre will automatically register a disk change on write-protected disks on
these drives and ignores write-enabled disks that get changed, whereas normally
it is the other way round. However, the GEM desktop will always cause a disk
access and update on both types of drive if the disks write-protected, whether
the disk has been changed or not. The only workaround without modifications is
to insert a write protected disk in the drive after removing / before inserting
a write-enabled one, but that makes Spectre think the disk has been changed
twice :-(
I most definitely do not wish to lose the capability of these drives to notify
Spectre of write-protect disk changes. Therefore it is not an acceptable
solution to hardwire the switch contacts in order to emulate the "normal" Atari
drives. I am seeking a solution whereby both write-protect conditions will
trigger a media-change event when a disk is changed. I imagine that a suitable
pulse generated by the media-change signals and drive-select signals could be
combined with the write-protect signal by some trivial logic to produce a
modified write-protect signal that would fix these drives - maybe even fool
Spectre to recognise any disk change once only.      8{:-)}
(BTW Epson and Citizen drives suffer also from the same problem). I guess that
the  drive-select signals are pulsed in turn and the write-protect line sampled,
in order to decide which drive has "glitched" the line. Am I missing anything
here? It sure makes better sense to make the same change (in hardware or
software) for all the drive types, than to fix each different make of drive with
a bodge that only works on that particular type.

(2)

Please can some kind soul tell me what pins 1,3,5,7,9 are used for on the Chinon
FX357 drives? I read that a certain amount of non-standardness exists here
between some of the manufacturers.

(3)

Can someone point me towards reliable DIY methods of getting the full speed and
density out of these HD drives? Has anyone already written a PD formatter and/or
driver for these beasts?

Thanks for reading, and any help welcomed!

Adam David.  adamd@rhi.hi.is