PCMCIA SCSI and CD Rom Drives

["John H. Kim" <jokim@MIT.EDU>]

Here's a followup report to the question I asked a couple days
ago.

I ended up buying at a local store and playing the if-it-
doesn't-work-return-it game.  I started with the Panasonic 8x
CD-ROM drive.  Linux didn't like the card.  I hacked the PCMCIA
config files so it would recognize the controller, but Panasonic
must be using a different version of the QLogic chipset in this
SCSI2 card.  The QLogic module, which works with the 4x drive's
SCSI controller, doesn't work with the 8x's controller.

So I got an Adaptec 1460A.  Linux recognized it, but the card
couldn't see the CD-ROM drive.  (Well, it could see it under
Win95 but we all know how DOS/Win doesn't care about important
things like interrupts and stuff.)  Lots of people reported that
the Adaptec SCSI2 controller recognized just about anything
under the sun, so my guess is the SCSI2 interface on the
Panasonic 8x is nonstandard somehow.

So back went the drive.  I got the 4x which lots of people have
reported success with under Linux, and indeed it worked. I
daisychained it with a SCSI zip drive and everything is
recognized.  I swapped the Adaptec card for the Panasonic and
everything still worked.*  Hot plugging works with both cards as
well.  I'm debating now whether to return the Adaptec and stick
with the Panasonic controller.

The only other incidents of note are the cable adapters. 
They're a mess. Zip drives use the Mac 25-pin plug.  The
Panasonic uses the 50-pin high density SCSI2 plug.  And the
Adaptec comes with a 50-pin centronics SCSI plug.  Cables that
convert from one to the other for plugging between devices (male
on both ends) are plentiful.  Gender changers and adapters for
changing between the types are nearly nonexistent.  I had to get
a SCSI2->MacSCSI adapter from PC Connection to be able to use
the Zip drive.  Even then, the sales guy I talked to had to
visit the warehouse to look at the thing to make sure it was
what we thought it was.  These things are also damned expensive. 
$15-$25 for an adapter, $25-$40 for a cable. 

I hope this is useful for others considering a SCSI controller
under Linux.

* Some people reported the Panasonic 4x SCSI2 controller hung
linux until they patched the module with a one-number change to
the source code.  I'd already done this trying to get the 8x
controller to work.  It works now, so I'm not going to bother
testing it with the original module.
--
John H. Kim
jokim@tuna.mit.edu