View Full Version : How Does "Cable Select" Work?

03 March 2003, 07:42 AM
Okay, can anyone explain how on the IDE channel, the function of "cable select" works? I'm still baffled @ how position on the IDE channel cand define primary or secondary devices. I mean gee, how does the system know which end of the cable needs to go to the board? Tech support said the reason I keep getting "no 80 conductor installed on primary IDE channel" is because I have the wrong end of the cable in the board.... does it matter? How?

03 March 2003, 08:12 AM
cable select tries to intelligently figure out which drive is plugged into which slot on an IDE cable by the order in which detects them.

you should always manually specificy master and slave in your systems to avoid any major hassels, especially if you are running multiple operating systems. it really isn't that hard to set a jumper once and then forget about it until you next change your system components around.

03 March 2003, 05:11 PM
It does matter what end gets plugged in.

Blue is for mboard.

Grey is for slave.

Black is for master.

Ditto on what elvis said.

03 March 2003, 06:33 PM
If you really want to know all the gorey details about cable select, read this article.

It really is a mess, avoid it.

03 March 2003, 08:08 PM
hey singularity2006, I was wondering why did you choose as a nickname a name (correct me if I'm wrong) from the Ayn Rand's Anthem book ?

(sorry for bad syntax...)

Revelation 23
03 March 2003, 08:40 PM
In CS, the second drive (furthest from the motherboard/card) will always be the slave. A large number of drives support CS, but most places don't have the CS cable (at least those I've been to). You can modify your hard drive ribbon (by severing one of the wires after the first connection), but doing so will render the ribbon unusable if you're not using CS. As said before, avoid CS. I don't really know why CS is still around - Master/Slave is easy enough as it is and the jumper settings are pretty much the same from drive to drive now.

03 March 2003, 10:07 PM
yea, CS is pretty useless now adays. And not as efficient in the end given some systems can get confused and mess it up. Best just Master and Slave. CS is fine if its the only drive in most cases. I have only had one incident where CS was required and thats when I was putting a second drive in a Cobalt Raq4. CS is even more useless once everyone converts to SATA since only one device can be on a SATA channel (for now anyways).

03 March 2003, 08:28 AM
wah.... interesting! No wonder all my Dell systems have 40 conductor cables with all the pins present... my older 40 conductors seem to be missing a pin in the middle. Anyhow, the Dells that I have seen all use cable select... which made it next to impossible for me to get stuff to work right because I installed a hot swap drive that I got from my uncle with no manual (I threw it away sometime ago after I got the thing working.... for a while). So I just took everything out, got new 80 conductor cables and had to redo the wiring using primary and secondary master and slave....

but as for my 80 conductor on my main workstation.... I just find it odd that the end would matter.... but okay. =D

Should I notice a performance difference by switching the end that is in the board? I'm not even sure if I can do that... stupid cable isn't long enough to reach my drives if I want it that way.... -.-"

03 March 2003, 09:21 AM
Dells have always used funky cables, either they are plugged like normal cables, or they arent, or they have a hole in the middle where a wire is cut (Cableselect), or they dont have the little nub on the top of the end so you know which way is up. Most that I have salvaged from old Dells are useless. The only difference between 40 and 80 pins are that 80s are meant for newer drives (you will get a warning on boot saying a 40 pin is being used). The extra wires shield the data wires from interferance from one another, i.e. CrossTalk. Same method as Twisted pair Cat5.

Most OEM systems assume you won't mess with the insides or add stuff yourself, so they can cutdown on build times/setups by just sticking stuff in there and pluggin it in since most drives come defaulted (jumperwise) to CS.

03 March 2003, 01:17 AM
So what is the use of that missing pin #20 on some cables? I have a mix of IDE cables.... some rounded, some not, some with pin #20 ... the one near the center, some with that sealed off. What's with that?

03 March 2003, 01:42 AM
that's just an unused pin that stops people physically putting things in the wrong way around. nothing exciting about it.

03 March 2003, 02:29 AM
fascinating.. i thought the little plastic "bump" on the outer edge of the connect was used for that....actually, my hot swap drive uses pin #20 for some reason so I had to get a cable that didn't have that hole filled in.

Anyhow, on the same note, I have my cables inserted correctly with the blue end in the board and my drives fitted accordingly but on bootup, my Soyo Dragon Ultra KT400 Platinum Ed. still gives me an error that says "80 conductor not installed on primary IDE" ... any ideas? I just bought a UDMA ATA133/100 cable too... still get that msg upon bootup, though everything still works fine.

03 March 2003, 04:19 AM
sounds like a dud cable to me. got a spare lying around to try?

03 March 2003, 05:54 AM
I've had this problem with three sets of cables now... I think it's the board.... -.-" I've flashed it one too many times perhaps... or their flash sux. I mean, overall, if I just leave the onscreen boot logo on, I will never see the error message, but it's in the back of my head that it exists when it boots.

CGTalk Moderation
01 January 2006, 06:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.