Cable Select vs. Master/slave settings

[Claude Jones]

On Sun August 7 2005 1:06 pm, Jim Cornette wrote:
> Just reporting something that came up in postings earlier regarding
> cable select settings vs. setting the jumpers on the devices, I tried
> cable select on my drives because I wanted to swap the primary CDROM
> with the Secondary DVD burner. The jumpers set to master / slave worked
> fine when the CDROM which is on the secondary of the cable select cable.
> The CDROM was set to master, While the DVD was on the master of the
> cable select cable.
> When I changed the DVD to master and set the CDROM to slave. both set to
> the same position on the cable select cable, the devices dd not become
> recognized correctly. (CDROM on secondary, DVD on primary)
> Changing the devices to both cable select allowed the DVD to be master
> and the CDROM burner to be slave as desired.
>
> This is sort of a retraction and a note that jumper selection settings
> on a cable select IDE cable can cause trouble, primarily with the
> secondary connector on the cable selectable IDE cable.
>

I see all sorts of declarative statements on this subject, here, and they are 
generally wrong. One thing I do in my job is hardware maintenance for a large 
collection of PC's of varying vintage, and with many different 
configurations. I've messed with bad jumper/cable select settings for years. 
The thing that can really bite you, because it's easy to forget/overlook is 
the following scenario: it is possible to get a system to work with a cable 
select cable, and the devices jumpered master/slave, or one jumpered master 
or slave and the other jumpered cable select - it's unpredictable, but when 
it works, it just seems to, well..., work. Scroll forward six months or a 
year, and you or someone else has to replace one of the devices; it's easy to 
waste a lot of time because you don't know, or have forgotten, that the 
system is configured improperly, and with the new device, things don't just, 
well...., work. If you have a cable select cable, jumper your devices "cs" - 
if you have a standard non-cs cable, jumper your devices master/slave. Follow 
this convention, and you won't have problems - I'd be willing to bet that 
everyone who's declared that you should ignore these protocols, and always 
jumper master/slave, or some other variation on this argument, have simply 
been lucky - they are victims  who just haven't been bit, ............., yet!

-- 
Claude Jones
Bluemont, VA, USA