IDE disk problem

[Jeff Vian]

On Wed, 2005-04-13 at 11:53 +0900, Joel wrote:
> Okay, I spent a little more time at the place that explained UDMA
> (pcguide.com) and I answered my own questions:
> 
> > [...]
> > > Cable select is exactly what it says, and is VERY reliable in my
> > > experience.
> > 
> > I used to repair computers with 5 1/4" floppy drives, and in those days,
> > CS was an epithet. Been a while since I've messed with mainstream
> > hardware. I'm going to have a lot of bias to get over if CS really is
> > reliable these days.
> > 
> > > -Use a cable select cable
> > > -plug the drive to be used as master to the connection designated as
> > > master.
> > > -plug the drive to be used as slave to the connection designated as
> > > slave.
> > 
> > So, if it's a CS cable, it should say on the connectors something like
> > "motherboard", "master", and "slave"? If it doesn't say, I can assume
> > the guy at Pasokon Koubou knew I didn't want a CS cable? Or maybe this
> > whole business is why he didn't want to recommend using the slave
> > channel in a multi-drive, multi-boot setup?
> 
> Blue is motherboard.
> Gray is slave.
> Black is master.
> 

If you put a hard disk and a CDROM on the same cable, the cdrom should
be the slave.  At one point the CDROM could not act as master for a hard
disk.  I understand some of the newer ones can do so now though I have
never tried it.

> > I guess I'd better take a look when I get home tonight. I don't want the
> > drives fighting with the cables on my new cheap Linux/BSD sixOS
> > multi-booting toybox.
> 
> Pin 28 is grounded for master, floats for slave. If CS is selected on
> both drives, the controller checks pin 28, but if one drive is selected
> as master and the other as slave, the controller ignores pin 28.
> 
> So, other than you want to put the master at the end anyway (to avoid
> data reflection on a non-terminated cable if you happen to remove the
> slave), as long as you make sure that one is selected master and the
> other slave, you're okay. 
> 

Generally, in my experience, intermittent errors can sometimes occur on
a CS cable with the drives jumpered as master/slave. I have never had a
problem with the drives set to CS though.

> Or you can let the cable select them.
> 

I _always_ let the cable select them.

> That's good to know. 
> 
> Thanks, guys, I guess I needed a reason to look that up.

Glad to help.