"CS" or "Master and Slave"?

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John

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.
 
If it's working leave it alone and be happy. Manufacturers of hdds allow
various configurations to allow the hdd to work by what other hardware one
already has hooked up on the system. Actually you could hook the hdd as a
slave, as long as it's jumpered properly, and make a CD-ROM a master.
To expand, many times I've added a CD-ROM writer to a system that insists
it must be a master. Sometimes it would not be seen on the OS unless I tied
it in as a slave. The drive would work fine when done that way.
And sometimes getting a system to run is akin to Han Solo pounding his
fist against the side of the consol of the Milenium Falcon to go to
Hyperdrive.
 
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.
Click to expand...

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.
 
MCheu said:
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.
Click to expand...

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.
 
In message <[email protected]> MCheu
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.
Click to expand...

Almost all of the drives I've bought recently have defaulted to CS
instead of master, especially drives that require 80wire cables.
 
Grinder said:
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.
Click to expand...

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.
 
The middle plug is slave and is usually grey, with the end plug master
and black. The motherboad connector is blue. Some early cables did not
follow the ATA specs. This probably tainted the use of cable select.
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.
Click to expand...
The early hard drives used FM or MFM data, and were driven from track to
track by
a stepper motor. The cable twist still survives in floppy cables,
although few computers now have more than one floppy drive. Cable
select on modern ATA drives is done by a ground on pin 34, which tells
the controller which is the master. Pin 34 on the slave, (middle,
gray), is not grounded as it is on the end, (black) connector. The cable
supplies the ground at the MB, (blue) connector, and the system will
complain if a 40 wire cable is used for a drive that needs an 80 wire
cable, since no ground will be seen by the MB controller.

Virg Wall
 
VWWall said:
The early hard drives used FM or MFM data, and were driven from track to
track by
a stepper motor. The cable twist still survives in floppy cables,
although few computers now have more than one floppy drive. Cable
select on modern ATA drives is done by a ground on pin 34, which tells
the controller which is the master. Pin 34 on the slave, (middle,
gray), is not grounded as it is on the end, (black) connector. The cable
supplies the ground at the MB, (blue) connector, and the system will
complain if a 40 wire cable is used for a drive that needs an 80 wire
cable, since no ground will be seen by the MB controller.
Click to expand...

Oops! Change: pin34 to pin 28, (CSEL). Pin 34, (CBLID), *is* used to
determine if an 80 wire cable is needed by grounding pin 34 at the MB.

Virg Wall, in a hurry to get to the turkey!
 
Using cable select will require a cable that supports the 'cable select'
function. As mentioned previously a 'cable select' cable will be labled
master at the end and possibly slave in the middle.
 
Using cable select will require a cable that supports the 'cable select'
function. As mentioned previously a 'cable select' cable will be labled
master at the end and possibly slave in the middle.
Click to expand...


'Cable select' cables also frequently have a hole in them. I believe that
the hole will be between the master connector and the slave connector. This
is how the 'open circuit' ,mentioned previsouly, is achieved.
 
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.
Click to expand...

?

I prefer cable select and almost all drives shipping now
ship jumpered to cable select.
 
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.
Click to expand...

The manual isn't exactly 'wrong'. Your shop just had another way of
doing things...and I still do it the way your shop does it. I always
change the jumpers to single drive...or master...or slave.

When you have the drive set to CS, the computer needs to read the
drives each time it boots...and then make a decision as how to handle
them.

With master, etc. settings, you already tell the computer which is
which...and that can speed the boot process. You can speed the
process further by changing the BIOS setting from 'auto' to the actual
parameters needed for that drive.

And, as was noted by someone here, you need a special cable when using
CS.


Have a nice one...

Trent

Budweiser: Helping ugly people have sex since 1876!
 
In message <[email protected]> Trent©
The manual isn't exactly 'wrong'. Your shop just had another way of
doing things...and I still do it the way your shop does it. I always
change the jumpers to single drive...or master...or slave.

When you have the drive set to CS, the computer needs to read the
drives each time it boots...and then make a decision as how to handle
them.
Click to expand...

That isn't entirely true -- The CS pin simply lets the drive jumper
itself correctly based on whether or not the PIN is set -- The company
doesn't make any more decisions in CS mode then in Master/Slave mode.
With master, etc. settings, you already tell the computer which is
which...and that can speed the boot process. You can speed the
process further by changing the BIOS setting from 'auto' to the actual
parameters needed for that drive.

And, as was noted by someone here, you need a special cable when using
CS.
Click to expand...

Virtually all 80-wire cables support CS.
 
In message <[email protected]> Trent©


That isn't entirely true --
Click to expand...

Sure it is.
The CS pin simply lets the drive jumper
itself correctly based on whether or not the PIN is set -- The company
doesn't make any more decisions in CS mode then in Master/Slave mode.
Click to expand...

Sure it does.
Virtually all 80-wire cables support CS.
Click to expand...

An 80-wire cable is a special cable on MANY machines yet.


Have a nice one...

Trent

Budweiser: Helping ugly people have sex since 1876!
 
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