Settle an Argument -- Master/Slave Connectors on IDE Cables

[Modus]

Greetings Anandtech'ers. (I've been absent for a few years; in the meantime I grew my techie business and got a diploma in software engineering. Currently I work full time as a programmer for internal business systems at a local software company here in Vancouver. It feels good to post in the forums again. I lurked for about an hour just now, and the place still has a nice atmosphere, which is a credit to you guys, the moderators, and the Anandtech staff including Mr. Shimpi.)

ANYWAYS, the question at hand is:

Under what circumstances does it matter which of the 3 connectors on an IDE cable plugs into the Master or Slave drive?

Your typical IDE cable looks like this:

[1]:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::[2]:::::::::::::::::[3]


A good friend of mine and fellow techie says that in all circumstances it is "better" to plug the Master drive into connector #3, the Slave into connector #2, and the motherboard (or controller) into connector #1. He says it might work the other way but some drives won't like it and you'll get slow detection in BIOS, data corruption, and stuff like that.

I say it only matters when at least one of the drives has its jumpers set to "Cable Select" or "CS". If you manually set them to Master and Slave, you can plug #2 and #3 any way you want, even on an 80-conductor ATA/66/100/133 cable. At least that's been my experience, and it seems logical enough. The Cable Select setting lets the cable select the Master/Slave based on which connector is used. Don't use Cable Select and the cable doesn't select!

We did a little test today and we didn't notice a problem with either cable configuration. Still my friend refuses to give in. What do you say? Does it matter which connector you use when neither drive is set to Cable Select?

Any links to technical docs and specifications to back up your statements would be helpful, too.

 

[tweeve2002]

I say it really doesnt matter unless you use Cable select...Shoot i have even use the #1 connector to connect and drive and the #3 to connect to the motherboard when the cable the normal direction wasnt long enough. either way I have never had any problems. In fact the computer with the upside down cable still runs great with no problems.

 

[AndyHui]

Hello Modus. Haven't seen you for a long time.

You are entirely correct. There is no detriment to plugging in the master and slave drives any way you want so long as you have the hard disk correctly jumpered. As you say, it only matters when you have CS jumpered.

If anything, I personally recommend plugging position [2] if the hard drive is going to be the only one on the cable, since it is closer to the controller.

Of course, with single devices only on a SATA cable, this sort of thing is going to be a lost art eventually.

 

[sharkeeper]

Either way, throughput is still lower and CPU utilisation higher on a Winmodem!

Cheers!

 

[Kaieye]

Modus, when I think of your name, I think of Lucent modems and the past debacle...

Welcome back!

 

[Zepper]

Hi Modus - Here, have a :beer: !

You should NEVER leave the end connector open - if you're not going to use it, cut it off! Andy H., don't you know anything of properly terminating HF lines??? It may work but it's not a good idea.
. As others have said, position only matters with Cable Select. But the convention has always been Master/Single on End of cable, Slave in the middle. In the old days of 40-wire cables, I often plugged the middle connector into the mobo with the long end to the farthest drive and the short end to the nearest. But those days are gone. On 80-wire cables the blue end MUST go to the mobo - it may not work at all if you plug the other end to the mobo.
. The 80-wire cables are ALL supposed to be set up for Cable Select with the Primary/Master on the End and Secondary/Slave in the middle (that's why all the connectors are color coded). In the old days the big box pushers like Dell had their 40 wire cables made for Cable Select and the primary was often in the middle (cables were marked so you know which is which) as that was the cheapest way to make them - just required a little punch hole in one of the wires.
. I use 80-wire cables and Cable Select all the time now. Oh, and if you do choose to cut the end portion off an 80-wire cable, you should probably set your drive to Master/Stand Alone as the CableSelect feature for the Primary drive is now gone. I'm not absolutely sure as I've not cut one yet.
. Hope that helps.
.bh.

 

[Modus]

Thanks for the confirmation, guys. Now does anyone have a link to a PDF or specification where this is spelled out in black and white? I suppose they wouldn't specifically answer this question, but there's probably a paragraph somewhere about how ATA/IDE connectors work with cable-select vs. non cable-select.

Hey Andy, good to see you. Check your PM. (Feels neat to type that again.)

Sharkeeper,

Either way, throughput is still lower and CPU utilisation higher on a Winmodem!

There are a number of reasons to avoid higher priced "hard modems," especially those made by 3Com/USR, in favor of a common PCI winmodem. . . WOOPS. Reflex action. Yup, I still have the copy/paste winmodem diatribe. Luckily everyone and their dog seems to have broadband these days, making it a moot point.

 

[Zepper]

. ieee.org spec for standard and UATA/UDMA IDE cables. And here is a link to a Hitachi/IBM detailed drive installation guide - see page 43... Linkage .
.bh.

:moon: