"Grinder" wrote in message
news:%Uqpd.85080$V41.10633@attbi_s52...
MCheu wrote:
On Thu, 25 Nov 2004 14:44:13 GMT, "John" wrote:


My eMachine 1860, running WXP, has been flakey on boot for a year now;
once it is on it is fine, but it hands on boot about 20% of the time.
Monday it simply wouldn't come up, hanging on "IOM.SYS" everytime.

I took it in to the shop. They found a cable was nicked and the jumpers
were wrong. They set them to Master and Slave. Now all is well.
However, I checked the manual and it says to set the jumpers to "CS".
The shop says the manual is wrong.
Does it matter as long as the machine is working? Presumably the nicked
cable was the problem the whole time.
Thanks.


You've basically got two choices with IDE drives on a given channel:

1. One drive as master, and the other as slave. As a matter of
convention, the master is placed at the end of the cable and the slave
in the middle, but this really doesn't matter. 2. Cable Select (CS).
You're still using the master/slave system, but
it's determined by the position on the cable. Both drives have to be
set to CS. The master is whatever drive is at the end of the cable,
the slave is whatever drive is in the middle. If you've got one drive
as CS and the other set to either master or slave, it *might* work if
the jumpers are correctly set for the position -- but it sometimes
won't. The CS system is often employed by big OEMs because they can just
have
the jumpers on all of their drives to CS. That way, they don't have
to worry about the jumper settings on the drives, they just grab a
drive off the stack, plug it into the current machine, and move onto
the next one. It's faster for assembly line building.

Smaller OEMs and hobbyists prefer to use the Master/Slave settings
because drives usually ship as being set to Master, and this way
there's no ambiguity when you need to trouble shoot the system. You
know exactly which drive has taken what position. Either way works, so
long as you remember not to mix and match the
settings, eg. CS on one and Master or slave on the other. It might
work, assuming it's on the right position, and the controller hardware
lets you get away with this, but it's not guaranteed that this will
work.

I just wanted to add a bit to this excellent description:

A "selecting cable" is typically stamped with "Master" (and possibly
"Slave") next to the corresponding plug.

I seem to remember that CS (Cable Select) was introduced in the days of the
original IBM PC by IBM and was originally for floppy drives.. It had a
twist of a number of strands in the cable between the two drive connectors.
This meant that when assembling PCs with more than one drive they did not
have to fiddle around setting jumpers for Master and Slave, the cable did it
for them.