Connector at the end of the cable is for the Master?

  • Thread starter Thread starter **Developer**
  • Start date Start date
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**Developer**

Is it true that for IDE hard drives the connector at the end of the cable is
for the Master and the other connector is for the slave?



Thanks
 
That is correct when speaking of 80-pin IDE cables and drives that are
jumpered 'cable select'.
 
**Developer** said:
Is it true that for IDE hard drives the connector at the end
of the cable is for the Master and the other connector is
for the slave?
Click to expand...


Yes, for Cable Select, as the other respondent says.
Master and Slave roles are really arbitrary, though.
They are primarily just to differentiate the 2 devices
on the same channel for the controller. If you have
2 HDs, and they are on different channels, i.e.
different cables, they can both be Master or both
Slave, or the Slave can be on channel 0 with the
Master on channel 1. If you have only one device on
a cable, though, put it on the end connector to avoid
having the length of cable between the middle connector
and end connector act as an "echo chamber" for signals.

The only other use for Master/Slave is as a convenient
way for the BIOS to choose its *default* HD boot order,
in which it puts the channel 0 Master first, then channel 0
Slave, then channel 1 Master, then channel 1 Slave.
But this default order can be changed in the BIOS at
any boot time by entering the BIOS and manually
changing it with keyboard input, making if you choose,
a Slave drive on channel 1 boot the OS. This order will
persist in the BIOS until manually changed again or until
the lithium battery runs down. This can be used as a
conceptually easy way (by not using dual booting) to
switch between OSes on different drives.

*TimDaniels*
 
Great

thanks

Timothy Daniels said:
Yes, for Cable Select, as the other respondent says.
Master and Slave roles are really arbitrary, though.
They are primarily just to differentiate the 2 devices
on the same channel for the controller. If you have
2 HDs, and they are on different channels, i.e.
different cables, they can both be Master or both
Slave, or the Slave can be on channel 0 with the
Master on channel 1. If you have only one device on
a cable, though, put it on the end connector to avoid
having the length of cable between the middle connector
and end connector act as an "echo chamber" for signals.

The only other use for Master/Slave is as a convenient
way for the BIOS to choose its *default* HD boot order,
in which it puts the channel 0 Master first, then channel 0
Slave, then channel 1 Master, then channel 1 Slave.
But this default order can be changed in the BIOS at
any boot time by entering the BIOS and manually
changing it with keyboard input, making if you choose,
a Slave drive on channel 1 boot the OS. This order will
persist in the BIOS until manually changed again or until
the lithium battery runs down. This can be used as a
conceptually easy way (by not using dual booting) to
switch between OSes on different drives.

*TimDaniels*
Click to expand...
 
REMOVEdeveloper@a- said:
Is it true that for IDE hard drives the connector at the end of the cable is
for the Master and the other connector is for the slave?
Click to expand...

Only if CABLE SELECT is used on BOTH drives. If not using Cable Select,
then the Master/Slave jumpers on the drives are used to determine it and
position doesn't mean anything.
 
Boy, so many details to know


Thanks



Leythos said:
Only if CABLE SELECT is used on BOTH drives. If not using Cable Select,
then the Master/Slave jumpers on the drives are used to determine it and
position doesn't mean anything.
Click to expand...
 
Only when using "cable select".

--
Regards,

Richard Urban
Microsoft MVP Windows Shell/User

Quote from: George Ankner
"If you knew as much as you thought you know,
You would realize that you don't know what you thought you knew!"
 
Richard Urban said:
Only when using "cable select".
--
Regards,

Richard Urban
Microsoft MVP Windows Shell/User
Click to expand...


Let me add just this to Richard's comment. He is, of course, correct in that
when the devices are configured Cable Select, it's the position on the IDE
cable that determine whether the system will treat the devices as Master or
Slave, i.e., the device connected to the end connector is Master, the device
connected to the middle connector is Slave.

If the devices are connected in a non-CS configuration, then it *usually*
will not matter if the device that is jumpered as Master is connected to
the middle or end connector of the data cable. However, many knowledgeable
technicians avoid the "dangling terminator" situation, i.e., if only one
device is connected on the IDE cable, they will invariably connect it to the
end connector and not the middle one. I do the same myself, but I really
can't confirm that it's necessary in terms of any performance issue, at
least none that I've experienced.
Anna
 
Thanks for pointing that out. It's also mentioned in version 7
of the spec on p. 16 in paragraph 7.1, Cable Configuration:
http://t13.org/docs2004/d1532v2r4b-ATA-ATAPI-7.pdf

I knew this to be true from basic electrical principles and I
suspected that the specified length dimensions of the cable
were to minimize the effects of signal reflections. But I have
found, like Anna, that modern ATA hard drives and controllers
are quite tolerant of deviations from cabling specs. For example,
I have used removable HD trays and "round" cables of various
lengths and no. of connectors for 2 years with no problems
(that I can *perceive*).

*TimDaniels*
 
Ah yes it "works", but the primary result of ignoring standards, is job
security for tech support. When things finally go pear shaped we have to
go thru and "fix" each one of these we find until the "cobbled together
system" works again.
 
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