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Rounding Out Your IDE Cables 129

Posted by CmdrTaco from the allright-thats-clever dept.
BrookHarty sent us a story that proves that sometimes it's the little things that are clever. Are you as annoyed as I am that those pesky IDE cables are big flat things that are hard to move around? Well, here's a HOWTO that explains, well, how to round them out! It won't solve global warming or change the world. But dang it, that's cool.
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Rounding Out your IDE Cables More

Rounding Out your IDE Cables

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  • IDE is a fairly high speed interface. The impedance between wires is controlled in order to maintain signal integrity. My instincts tell me that slicing up an IDE cable and rolling it might work, but you could easily end up with data corruption.

    Trusting the word of Senior Technical Support seems a bit dangerous. It's just a nice title, if he really knew what he was doing he wouldn't be answering phones. I'd hold out for an answer from an electrical engineer who understands system electrical integrity issues.
  • Well.. look at it this way.. if those cable are that sussepable to interference. The you are all ready in deep doo-doo condidering how many other wires, especialy power cables run right next to them.

    Off the top if my head, Ethernet cables would generaly be alot longer in length, which is why they might double up. I think lenght/resistance is the biggest killer, as opposed to interferance from other cables.

  • The duller the blade, the greater the pressure.

    pressure = force / area
    if area is .005 m^2 (duller) instead of .001 m^2 (sharper) you are going to get a smaller pressure. so you want a sharp blade for more pressure. it is harder to stab someone with a spoon for example because there is so much area of application so little pressure to break the skin.
  • In the early days of my engineering experience, we used flat ribbon cable not because it was cheaper but because it was an easy way to maintain balanced transmission lines without resorting to prohibitively expensive coax cables. Anybody ever see an old IBM channel cable with the morphadite connectors? What a nightmare!

    Anyway, the ribbon was arranged with alternating signal and ground conductors to maintain the balance of current which reduces crosstalk. Separating the individual wires and then mixing them up will cause problems.

    Leave it alone or else use twisted pairs. You ever wonder why twisted pairs are used? Well now you know.

    Also as to the use of terminators, anything over 6 inches long needs to be both balanced and terminated. Old LS logic could get away without it for longer runs but newer ALS logic with sub-nanosecond risetimes is noisier than hell and rings like a bitch if not properly terminated.

    Guys this isn't just 1's and 0's anymore. It's gigahertz RF theory!

    Bottom line: If it works, don't fix it!

    Edwin
  • If making cables' isn't your thing...Plycon Computers [plycon.com] (my favorite vendor online) sells them, both ATA-33 and -66, as well as SCSI and floppy drive connectors.

    Very expensive, sure, but waaaay cool and they certainly can't hurt airflow in your case.
  • FYI - running the bus out of spec isn't going to bug SCSI. Look at your SCSI card - it has a on board crystal to deal with the SCSI clock rate.

    I wouldn't worry too much about doing the mod on 50 pin SCSI - but I wouldn't touch 68. Most SCSI problems are cable problems, and if you're just getting some retries, you wont even necessarily know it, until it screws you.
  • Actually, I have found that a thin guitar pick does quite a good job, although it seems better to cut the cables starting from the middle, and make progressivly narrower strips.

  • Um 100BaseTX full duplex. And like ethernet is a standard which can use a variety of Layer 1 mediums.

    IIRC 100bTX is still only 4 wire. the full duplex means nothing because even 10bT uses a PAIR for TX and a PAIR for RX. 4 wires total. I believe 1000bT uses all four pair.

  • The reason that ribbon cables are flat is to preserve the phase relationships of multiple signals in a cable while at the same time reducing in-cable interference to a reasonable level.

    So what you should do is only to separate the two and two. No, it is not twisted pairs (they are not twisted :-) ) and they are not real balanced in the DM sense, but the current going out of the one is suppose to run back in the other, which happens to be a ground wire. If it was suppose to be a real DM, it should mirror the signal wire.

  • I think what he meant was that with dull knives, one tends to use more force than you would otherwise, which means that when the knife sleeps you end up with a nice, deep puncture wound, instead of a nick from a sharp knife moving at lower speed that hits you. You're right about pressure and spoons, of course, but the general rule with knives is that ones that are a little bit dull are more dangerous than sharper ones. Dull knives encourage excesive force, and foolish habits that are painfully unlearned the next time you pick up a sharp knife.

    "Sweet creeping zombie Jesus!"
  • I used the Hard|OCP [hardocp.com] guide myself and wound up with a bunch of ruined, but fortunately, old cables. I learned that it is nearly impossible to make a cut along the cable's entire length with the kind of precision necessary to avoid breaking the cable.

    Then I thought about it. The smaller the cut, the smaller chance for error. Objects follow the path of least resistance. If you just make a small cut into one of those grooves, then peel the cable apart, it is almost impossible to screw it up -- you are less likely to make a bad cut, and the thinner shielding in the grooves will ensure that the ribbon will split right down the middle.

    WARNING: the above comment does not link to goatse.cx [goatse.cx]

  • To minimize the effects of multiple induction (a transmission line characteristic) all Slashdoters should twist the lines before bundling (obviously if you seperate the lines in groups of 4 or 5 it will have a minimal effect). If you look inside a serial cable (RS-232) you will notice that it is twisted for the same reason. Regardless, Slashdoters should know that without shielding they shouldn't leave an open case around their ham radio antenna -or- try to use these bundled cables to connect externally for a significant distance.

  • standard for the future? (Score:3)

    by Tumbleweed ( 3706 ) on Saturday November 18, 2000 @09:52AM (#615544)
    > I'll bet that these kinds of cables eventually become the standard,
    > especially if the cooling requirements for x86 hardware is going to
    > start requiring 1lb. heatsinks like the upcoming P4...

    You bet they will - but perhaps not why you think. SerialATA, the Intel-created (or just backed?) upcoming standard for connecting low-cost harddrives (i.e. non-SCSI drives) have cables about the size of a CD-Audio cable. Very cool (but not as cool as IEEE1394b). Very nice for cooling.

    Weren't we all supposed to be using FireWire harddrives by now? *sigh*

  • Thats why SFF-8049 specifies an 80 conductor cable. I guess that the HF impedance is around 120 ohms. Splitting them apart is only going to result in trouble with mismatches, reflections and data corruption.

  • FireWire may be faster than SCSI but I don't believe that FireWire is faster than FibreChannel. A FibreChannel controller that I worked on did around 190 megabytes per second. Can any FireWire controllers push that kind of data? (not trying to be cocky, just asking)
  • If you have an overclocked system, the extra air flow you can get by bundling the IDE cable will be a nice surprise.
  • Any idea how many firewire drivers you can daisy chain? PCNation has 80gigs firewire HD's for 358. 40's for 256..
  • that's right, the electrons go down one wire and come back on the other.

    i assume "TPI" is twists per inch or something. if so, you're wrong. maybe cheap cable has the same rate of twist on each wire, but strip some insulation off of some good cable and see for yourself.
  • So what? It still can't beat project submersible [octools.com]. NO2: the only way to chill =)

  • IDE not ATA66 (Score:4)

    by don_carnage ( 145494 ) on Saturday November 18, 2000 @09:12AM (#615551) Homepage
    From everything I've read, it's a pretty easy and painless operation with IDE cables, but don't touch those ATA66 cables unless you have a lot of money to spare.

    The trick is to use your fingers (if you can) instead of a knife to avoid severing a cable.

    --

  • Your McGyver smoker must really be low on supplies when he starts using IDE cables to roll his shit up.

  • Re:What if you're too lazy? (Score:3)

    by Anonymous Coward on Saturday November 18, 2000 @10:04AM (#615553)
    For one thing, it takes out the geek/hacker/1337 element of rounded cables, and for another, Plycon is highly overpriced and overrated.

    Places like 2CookTek [2cooltek.com], teamawe [teamawe.com], and Case ETC [caseetc.com] have the same products with better explanations of what you are buying at more reasonable prices. I guess the disadvantage is that you don't get to have a site with fancy animated GIF's.

  • This was all the rage on the hardware site message boards (anandtech etc.) well over 1.5 years ago.
  • For the unenlightened, a 'DC-RW' is a CD-RW that writes backwards...or maybe I just can't spell :) Here i was thinking you had a GD-Rom rewritable for DreamCasts... hmph
  • Some Links about Karma Whoring:

    www.everything2.com/index.pl?node=karma%20whore [everything2.com]

    www.cybernothing.org/~holychao/karmaho.html [cybernothing.org]

    www.wirednews.com/wired/archive/8.07/mustread.html ?pg=9 [wirednews.com]

    http://slashdot.org/users.pl?op=userinfo&nick=sign al%2011 [slashdot.org]

    This place should give a lot of resources too:
    http://goatse.cx [goatse.cx]

  • This has been done a lot before, I read a lot of other news sites, and mainly people into heavy case modification, or those who overclock a lot(the rounding allows air to flow better around the case, which helps to get rid of the extra heat generated by overclocking), round out their IDE cables. I've done this before, but I've also killed some cables before, if you try this becareful or you might be heading down to a store to get some new IDE ribbons.
  • I'm guessing rounded cables improve airflow and might make it easier to route cables through wierd places.

    However, don't ask me why they cut them instead of folding them. I took an old IDE cable and practiced with it, I can fold it into 1/4 its width with no difficulty, and it seems safer then cutting.
  • I've rounded my IDE cables plenty of times, and I've never had any corrupted files, or problems at all.
  • I have two homemade rounded 50 pin SCSI cables. Both of them work. I have never gotten a CD-R coaster or ended up with corrupted data, in spite of the 83 MHz FSB overclocking that causes the PCI bus to run ~25% out of spec @41MHz...

    I had less luck with this manufactured round cable [compgeeks.com], and wound up removing it because it caused the SCSI bus to constantly reset.

    WARNING: the above comment does not link to goatse.cx [goatse.cx]

  • ...and took the idea a bit further. (The IDE cables inside a TiVo are split into groups of four or five (can't remember) wires each, which allow them to be neatly routed in a fairly confined area.)

  • Re:It's a square wave - not a sine wave. (Score:4)

    by willy_me ( 212994 ) on Saturday November 18, 2000 @08:39PM (#615562)
    Since wavelength at 66MHz is about 4.5 meters, I don't think transmission line effects are all that important on short 1 foot cable (yes I realize SCSI needs terminators but that is slightly different).

    Just in case you didn't know, a 66MHz square wave is made up of several (ok, really unlimited) different sine waves. You need to look at the rising and falling times of the signal if you want to calculate the RF produced.

    Also, look at an FM transmitter. One inch of wire is enough to transmit a signal!!! Even AM doesn't require that big an antenna while it operates at a blazing 1MHz. The 66MHz signal will most definitely be producing a ton of RF.

    The ground lines are nothing more than shielding in this case.

    Are you serious? You really think putting a wire next to another wire will provide shielding? No, sorry bud, that's just not how it works. Shielding can be provided by completely surrounding the transmission line with a ground wire - like with your TV cable or RCA wires. An extra wire does nothing to stop RF.

    So why do people put ground wires by transmission wires? It's actually not usually like that. The two wires aren't positive + ground, they're a differential pair, like your ethernet cable. The idea being that one wire is more positive then the other. So then when a pile of RF comes along and jolts the voltage up in those lines by 20%, the data isn't lost because the relative voltage of the two lines isn't effected. The second line protects against data corruption, not RF production.

    This reminds me of a cool lab I did back when I was in school. Our class wired several RS232-RS422 converters to connect to the serial ports of different PCs. We then connected them all to a single differential pair (ie, two wires). After writing some software we had our entire lab networked via the serial port! Ok, it sounds lame but was great fun to implement.

    Willy

  • Hey, in the same store I found the FireWire drives, an 80GB 100/ATA is $320.

    Yeah, I needed to get another controller... but let me see you chain a scanner, camcorder, PS2(whatever good that is), an 6 hard disks to your built in controller? That's the limitation of your puny built in controller ^^

    The nick is a joke! Really!
  • 63 devices, I think... maybe a repeater could allow for more devices?

    The nick is a joke! Really!

  • FireWire speeds / FireWire advantages (Score:4)

    by Tumbleweed ( 3706 ) on Saturday November 18, 2000 @09:19PM (#615565)

    IEEE1394a (current standard) tops out at 400Mbps (megaBITS). The upcoming IEEE1394b standard spans 800-3200Mbps.

    SCSI drives are currently made with interfaces for 160MBps (megaBYTES), and the newest standard - don't know if it's finalized yet - is 320MBps.

    Obviously, hard drives cannot transfer at anywhere NEAR those rates, BUT, there's still a reason for them: multiple drives! With the advent of RAID (ATA RAID controllers built-in to motherboards are all the rage now), then these speeds become much more justifiable.

    The problem with FireWire hard drives is, as far as I know, there aren't any that have NATIVE FireWire interfaces on them - they're still ATA native devices with FireWire converters built-on to them (usually made by TI). From what I've read online, the current crop of TI chips aren't too efficient, but the next generation (due now or soon) are much better. Nevertheless, I'd feel better about harddrives (I prefer IBM these days) with native FireWire interfaces. Let's hope IEEE1394b gets here right quick.

    The advantages of FireWire are numerous:

    • You don't need a computer (you can connect, for example, a fireware hard drive directly to your firewire video camera or digital still camera, or whatever - no computer in between needed)
    • hot-plug capability built right in without any extra work necessary
    • you can chain I think up to 63 devices to it - that blows away scsi, ata, and I think serial-ata
    • cable lengths _much_ better than SCSI or ATA
    • say goodbye to ribbon cables

    That's all I can think of right now - I'm sure there are more.

  • Actually it's in the world of analog audio where signal degradation (or more accurately the avoidance of it) is of utmost importance.
    If you want to worry about it in IDE cables then take each line and the ground line next to it and turn them into twisted pairs but don't expect tobe able to get away with a whole lot more length than the flat cables.
    Get a hold of a Mouser or Digi-Key catalog and you'll find that you can buy prefab ribbon cable manufactured round instead of flat except for a place every so often where it flattens out for installation of connectors. You might even be able to get it shielded or unshielded.
  • errr overclockers have been doing this for YEARS now... even a DECADE with scsi cables... and i get inside my computer about 5 times a day hehehe



    Love's like playing "Marvel Vs. Capcom" with the default Dreamcast controller: Lots of fun but it hurts like hell
  • "...how about a way to make IDE cables impossible to plug in upside-down?"

    There are already 2 ways, but cost shaving does in both of them. One way is using shrouded headers (the part with the pins). The shroud has a notch in the middle on the odd number pin side (1,3,...39) and the Insulation Displacement Connector crimped onto the cable is supposed to have a corresponding "bump". But headers without shrouds are cheaper. The other way involves the absence of pin 20. It isn't there on the header and the corresponding hole on the plug body is filled up, but that adds at least one more step to the manufacturing process, which adds cost.

    At least it's not as bad as those 10 pin headers for serial ports. Some of them have pins 1, 2, 3, 4, and 5 in one of the rows and pins 6, 7, 8, 9, and the never used 10 in the other row, whereas others have the odd number pins on one row and the even number pins on the other row. This means that when the 9 or 10 conductor ribbon cable gets to the DB-9 or DB-25 connector at the other end there are two choices of how to wire it and the one that was right for your old motherboard or controller card may not be right for the new one. I've even got an old Zeos 486 board where the Com 1 header is set up one way and the Com 2 header is set up the other, so that it isn't even consistent right there on the board.

  • For the clue impaired, ethernet does use all 8 wires. Unless you're using castrated half-duplex ethernet. If you have a collision light, you're cutting your bandwidth in 1/3! And your bidirectional bandwidth in 1/6! Buy a 10/100 switch rather then a hub, set all the ports to full duplex, and watch your data scream.

    Is this a troll? 'cuz if it is, I guess IHBT. 10BaseT uses 4 wires, a pair for transmit, and a pair for receive. 100BaseTX uses 4 wires also (but requires twistier Cat5 cable). 100BaseT4 uses 8 wires, but will work with older Cat3 cable. And collisions don't reduce your bandwith to 1/3, or by 1/3, or whatever you meant by "cutting your bandwidth in 1/3".

  • Well duh, thats what the article tells you to do. Anyways, its better to use a duller blade because you can still use it to separate the wires while not having the chance to make cuts into the thicker insulation surrounding the wire. It only took me about 30minutes my first time.
  • I've done plenty of these, and the trick is to use the blade as little as possible. Nick the cable between the wires, then just pull them apart. You must absolutely, positively, not try to cut the entire length of the cable, you'll never get it without screwing up. It shouldn't take any more than 5 minutes for this little procedure.
  • you didn't just put a small cut on the cable, and then gently pull the cable apart to split it? Works much better than trying to cut the entire length of the cable.

    also, i just separate wires in groups of five, so it doesn't take so long. Then, just stack them up, and use a zippy tie or electrical tape to secure. easy, and pretty fast. probably not as 1337, though...

  • Serial ATA will be nice too... (Score:3)

    by jerky ( 22019 ) on Saturday November 18, 2000 @10:26AM (#615573)

    Eventually you won't have to worry about rounding out your IDE cables. Low-end hard drives will go from parallel ATA to serial ATA. Serial ATA cables will be nice and thin with a lot few fewer conductors. You can read more about this at serialata.org [serialata.org], but the basic idea is that hard drives will transition to a software compatible, 1.5 Gb/s serial connection. Among the benefits promised are "easier routing of cables." A serial ATA drive has already demoed but they're not promising systems until 2002.

  • A 80gb FireWire drive is $369... A 45gb drive is $250

    A FireWire controller is only $100...

    Why aren't you using FireWire drives yet?

    The nick is a joke! Really!
  • You don't have to be careful with ATA/33 cables. I cut them freehand with a razor blade, not being particularly careful. I mostly got them right, but sliced into two or three wires by mistake. I didn't sever them, of course, but you don't have to worry about stripping the insulation off a wee bit (as long as two such wires don't connect, of course.
  • We used to have a bunch of HP Apollo workstations that came with scsi cables that had been split this way. They were sliced down to individual wires. We had problems with conductors breaking over time. Our best guess was the the seperated wires flexed too much when vibrated by the fans and drives.
  • How exactly does folding the cables differ from splitting the wires?

    Both ways, the wires will no longer be flat with each other, and all wires will still be the same length.

    Unless you're trying to say there's some magical magnetic/electrical properties which have to be maintained for IDE cables.

    SCSI, otoh, may be a different story


    ---
  • Yeah congratulations, Slashdot would like to welcome all you Mac users who stay up late worrying coz your PC cables are flat not round. Bet you all drink Pepsi.
    --
    Never try to teach a pig to sing. It wastes your time and annoys the pig.
  • Nothing beats this cooling http://www.hexus.net/wc2.shtml [hexus.net] Seriously Manic guys.
  • Coming from the hi end audio field, there are many electronically sound reasons for ribbon cables, induction being the primary reason. Rounding the cables may not damage your computer, but it will most likely slow down the data transfer, and increase data corruption.
  • Why not use a damn chainsaw to cut the cable. Now that would be interesting.

    It must be a slow news day.


    there are 3 kinds of people:
    * those who can count

  • both 3M (Scotchflex) & Thomas&Betts manufacture twisted pair round cable rolls (all the way from about 10 core to 70 core). However its not as simple as that, with round IDC cable, the cores have to be split from each other otherwise the round cable would buckle & also spring back too much, of course the more expensive twisted pair variety has to be split for the cores to twist too. However one also has to have a unsplit patch every 3 inches or so, of at least one inch in length, along the length of the core, underneath the outer insulation - otherwise it'd be a bugger of a job attaching IDC end clamp connectors to them. Consequently if you purchase a roll of the stuff, & you plan to make IDE or SCSI cables you have to cut them an extra 3 inches or so, because you might have to backtrack a bit to unraval a flat unsplit length to attach the IDC connector to each end. Twisted pair round IDC cable rolls are expensive. So if you see SCSI IDC round cables going cheap, they are either handmade jobs made from ordinary ribbon cable or its made from a roll of ordinary round IDC cable.
  • Is the person that posts links about Karma Whoring, themselves a Karma Whore?

    I think they are :-)
  • You know, because they're well rounded?

    ------------
    CitizenC
    My name is not 'nospam,' but 'citizenc'.
  • To clarify, people seemed to miss it. I did only cut it a very small amount, then pull the rest apart. But you still have to be VERY careful when you cut into the cable.

    -Julius X

  • There is an electrical effect called the "transmission line effect".

    A cable can be modelled (for high-speed signals) as a series of inductors, resistors and capacitors.

    If a certain relation between the values of the inductors, and capacitors exists, the signal will surprisingly come out the other side, very similar to how it went in. Take a garden hose and shake it up and down. You can make the waves "walk" through the hose. That's the effect.

    This effect is most clearly observed with coax cables. There are several "waves" of TV signal on the wire, even if there is only a few yards of cable between your wall-socket and the TV.

    Now, in a ribbon cable, a signal that has a "ground" conductor on each side of a signal, this effect is noticable enought to be useful.

    For UDMA33, and especially higher, the transmission line effect becomes noticable, and required for correct operation.

    If you just pack a bunch of lose cables in a bundle with tiewraps or stuff like that, this will not guarantee that there are ground conductors next to the signal wires.

    As an experiment: Try making two round cables. One with the odd and one with the even numbered conductors. You certainly shouldn't be able to run UDMA66 anymore.

    I really don't know who you talked to at WD. They DO have people who know this, but apparently the guy you talked to didn't.

    Oh, you will probably be able to get away with splitting the cable in pairs. But for the tranmsission line effect to really work, the fact that there is a ground line on the other side too really helps.

    Roger.
  • 1) My Karma is capped, so I have no incentive whatsoever to Karma Whore.

    2) I intentionally threw in a goatsecx link.

    3) Proper moderation would be: (-1, Flamebait) or (-1, Offtopic)

    Thank you.

  • Internal Round cables have been around for ages for disks. They use twisted pair wires in regular cable jacket. The jacket is stripped off and an IDC connetor mounted on the cable as needed. Look in a fault tolerant Vax (now compaq) from about 10 years ago.(You must have one somewhere, right?)

    There are round cables going to the DSSI bus disks in the disk bay. If you got SCSI disks, you have round cables as well.

    The driving force for PCs has been cost, and putting connectors on a flat cable takes seconds. With round cable you have to manually dress out the wires, put them in the right order by color, etc. before you can terminate on the connector.

    Round cables for external disks (SCSI) are very common even for PCs.

  • rounding cable tips (Score:3)

    by beckett ( 27524 ) on Saturday November 18, 2000 @10:41AM (#615589) Homepage Journal
    use your fingernail to separate the cable is better than using an exacto knife. that will avoid cutting one of the wires in the cable. if you do, then you start all over. if you have to use a knife, just make a small inscision and tear down the length of the cable.

    also, when you are separating, forget separating each individual strand. I'm not sure why this article said to do this. from my experience. just make an incision every 4-5 wires, and the cable will "round" (well, rectangle, really) just as well. less cuts means less chances to make a mistake!

    lastly, i wouldn't even touch those ATA-66 cables. there are way more worries about possibly cutting one of the much thinner wires, and there is also mention of potential crosstalk interference with those high density cables. i have found that merely twisting the cable together so it "rounds" and then using zip straps works wonders. These ATA-66 cables are not as plentiful as the piles of 33 cables you have sitting around. don't split those!!!!

    because i'm an [H]|OCP'er, check out their article on rounding too. at least it's only TWO freaking pages... fewer banner ads to distract you, i say. the [H]ard|OCP article also tells you about cable placements.

    http://www.hardocp.com/articles/cooling/round_cabl es_howto/round_cable_howto _pg1.html

  • "It won't solve global warming or change the world. But dang it, thats cool."

    Do you have a problem with the sun warming the earth? Now ridding the Sun from the earth.. Thats a big problem!

  • Re:Cable Impedance (Score:1)

    by Anonymous Coward
    Not if you keep each signal line attached side-by-side with its corresponding ground line. I've been slicing SCSI cables this same way for years without a single glitch.

  • The duller the blade, the greater the pressure. The greater the pressure, the higher the likelihood of injury and/or making a mistake.

    WARNING: the above comment does not link to goatse.cx [goatse.cx]

  • for one thing, this isn't news. i just thought i'd point that out. there have been tutorials on how to do this forever on enthusiast sites like virtualhideout, etc. not to mention plycon [plycon.com] sells pre rounded cables. but anyway, as long as you have a sharp enough blade ata66 is equally possible (but if you're scared you can always pay $30 to have someone else do it for you...)

  • Uhh. Why, exactly, is this news? The old X-Acto knife trick's been around for years.


    Chas - The one, the only.
    THANK GOD!!!

  • Both 3M (Scotchflex) & Thomas&Betts sell round IDC cable by the roll, all the way from about 10 core to about 80 core.. However its not as simple as that, with round IDC cable, the cores have to be split from each other otherwise the round cable would buckle & also spring back too much, of course the more expensive twisted pair variety has to be split for the cores to twist too. However one also has to have a unsplit patch every 3 inches or so, of at least one inch in length, along the length of the core, underneath the outer insulation - otherwise it'd be a bugger of a job attaching IDC end clamp connectors to them. Consequently if you purchase a roll of the stuff, & you plan to make IDE or SCSI cables you have to cut them an extra 3 inches or so, because you might have to backtrack a bit to unraval a flat unsplit length to attach the IDC connector to each end. Twisted pair round IDC cable rolls are expensive. So if you see SCSI IDC round cables going cheap, they are either handmade jobs made from ordinary ribbon cable or its made from a roll of ordinary round IDC cable. The simple fact is, if you were to open up many brand name computers (such as the latest Compaqs), they actually have round IDE cable in them & many profesional workstations (such as some IBMs) now have round SCSI cable in them to. The reason is it aids ventilation in those cramped Compaq PCs & in those hot workstations. I agree with you on the proper art of folding & routing IDC cables, though.
  • That's all.
  • Yech, I can only imagine what that would be like; was horrible enough the one time I used a small piece of masking tape to hold together a J that was unraveling. Blech!

    Deo
  • manufactured twisted pair (& non twisted paired) round IDC cable is expensive. Just ring Newark/Farnel & ask them what the price of a roll of 80 core round IDC cable is? You have to remember that about every 3 inchs the cores have to be flat & joined for about an inch, so IDC connectors can connect to them. The rest of the core has to be split so the cable doesnt bucklwe or spring back (& so the twisted pairs can be twisted too, in the twisted pair variety)
  • Hmmm, FibreChannel seems to do as well or better in a bunch of areas:
    • Speed - 4.24 Gbps
    • Topologies - Point-to-point loop hub, switched, fabric. FC controllers can talk to fc hard disks and fc tapes drives without an os. FC hub/switches can talk to all devices on the loop for administrative control.
    • HotPlug - Just plug it in, plug it in. To a closed loop, a hub, a switch, a fabric, etc.
    • Device Limit - Don't have exact number but I remember it being way over 63...anyone have it? In my testing of my old company's fc controller we had as many as 300 devices on one loop.
    • Distance - 10 Km. Who needs wireless when you have a long cable? :-)
    • Ribben cables - You can use fibre optical or copper based connectors. Either way, the cable is small and bendable.


    I think that FireWire has a ways to go to catch up to FC. I would like to see one standard but the best technologies are the most expensive and the average user doesn't have the money or the need for the best technologies. Let FireWire, USB, and SCSI slug it out while FC holds the server crown. Oh...and somebody please kill off IDE!
  • I think it may also be due to the fact that the signal is differential. (like 10/100BaseT and RS485) un-paired cable just wouldn't work at
    the rates needed. This is just a guess I haven't read the UW specs, so don't flame me if I'm wrong!
  • Nice, but FC is _vastly_ more expensive than FireWire, especially in the controller/adapter area. You can get a IEEE1394a PCI adapter for well under $100 now. Not sure how much the IEEE1394b adapters will be, but I bet they'll still be much cheaper than FC.

    I agree, though, that FC is some schweet technology, though.

    re: who needs wireless when you have a long cable

    Uhm...yeah, right. :^) Let's go for Ethernet over FC! '4240BaseT', woohoo!

    I live in an apartment, so no running cables between rooms for me - can't wait for those new 802.11b and e devices shown at Comdex.
  • I'm not sure about using ATA66/100 cables for this eather. The reason they put more pins in there in the first place is to shield the active ones. I'm not an electrical engineer, but it seems putting these cables on top of one another like that should cause some problems. Some information from a Quantum ATA66 white paper:

    "The addition of 40 extra ground lines to the Ultra ATA cable spec considerably reduces signal crosstalk and ringing between the data lines (Figs 2 & 3). That allows the lines to "settle down" much faster, thereby slashing setup times in half. And that is what enables the Ultra ATA/66 interface to transfer data at twice the Ultra ATA/33 rate without requiring any other significant changes to the Ultra ATA specification, especially to the DMA protocol.

    The 80-conductor cable is mandatory for running Ultra ATA/66. The usual 40-conductor cable ATA cable cannot handle the higher speed, and because the cables are plug compatible, the system must determine the presence of the correct cable. "

    Reference: http://www.quantum.com/ src /whitepapers/wp_ultraata66.htm [quantum.com]
  • or original.
    All of the scsi cables in any of the HP/Seagate disk arrays that I have are like this.
    3M sells SCSI and ID cables like this.
    I prefer them, but mostly becaause they have the flap on the back side of the conector to unplug with instead of pulling on the cable itself.
    Yeah so, before you go slicing things up, you should decide whether it isn't worth the few dollars to just purchase one.
    -xt
  • And you, sir are a troll. Read the FAQ [slashdot.org]

  • This can work with old IDE cables or SCSI-1, but don't try this with the higher bus speeds of SCSI-2 or anything faster or with UDMA IDA drives.

    These lines are parallel for a reason (every other one of them is ground) and you will get interference (read: data loss) if you're not extremely lucky. If you want round cables, buy them pre-made, where each data line is twisted with its matching ground line to halt interference.

  • I meant Fast SCSI-2 or faster...
  • >Would'nt this have some interference?

    For modern ATA-66 cables and SCSI cables, I would think so. These cables alternate DATA/Ground pins for sheilding/impedance purposes. When you separate these cables, you change the shielding and impedance properties of the cable.

    To create a properly rounded ATA-66 or SCSI cable, you really need to separate it into pairs of Data / Ground, or else you change the properties of the cable. You'll likely get crosstalk and interference from the computer otherwise.

    Oh, BTW: The 4 pairs (8 wires) in CAT 3/5 ethernet cable are there because in most standards you can use the other 4 wires for voice or another Ethernet connection. Also, the added redundancy means that if a wire turns out to be cut somewhere along the run, you are still OK (use a different pair).

    Some ethernet standards actually use all 8 wires (like 100VG... that stuff's neat, doesn't use CDMA in the normal sense).
  • When U2W SCSI first came out there were a lot of problems with cables that were a little too noisy. The answer? Twisted pair. Each signal cable twisted with it's ground neighbor.

    It seems like the same thing would benifit ata66/110.

    It seems like you used to be able to get 40 pin header connectors with no wires attached . . .

    -Peter

  • obviously you can't cut utlra160 scsi cable because it's already separated and all twisted up. i'm wondering if interference would occur if i were to zip tie the cable, and perhaps just fold it (without cutting anything) to reduce the space. is there a reason not to do this? cuz that thing takes up WAY too much space in my case...

  • The Dumbshit way of doing things... (Score:5)

    by human bean ( 222811 ) on Saturday November 18, 2000 @11:03AM (#615612)
    The reason that ribbon cables are flat is to preserve the phase relationships of multiple signals in a cable while at the same time reducing in-cable interference to a reasonable level. As speeds for data transfer become higher and higher, this becomes more and more important. Fortunately, most data transfers are now intelligent enough that error correction takes care of most of the glitches that used to stop systems in their tracks.

    Rounding cables like this is a time-wasting method of destroying all that paid-for engineering. Try one of these instead:

    1. Look in the Newark (or similar) catalog and buy one, for pity sake.

    2. Take the long section (what you are most concerned with), carefully fold it up lengthwise, and slide it into a length of half-inch split loom tube (any good parts store for about fifteen cents).

    Either of these will get you where you wanted to be, which was moving that cable out of the way. Also note that IDE and especially ATA cables must be cut to a certain length to avoid possible SWR problems. You might also look up the proper folding and routing of ribbon cables, which seems to be a lost art among PC manufacturers these days.

  • I just tried this, and it works way _way_ better if you use a Pizza cutter. (they were intended for cutting in straight lines) If yours it truely dull, consider getting a new one anyway -- crust is hard to cut with a dull knife. --Advice from the Pizza Hut professional I am--
  • External SCSI cables are carefully arranged to minimize the interference. The cable is arranged in layers. The ground lines are all placed on the outside layer, with the data lines on the next layer, so the data lines are all close to ground lines to minimize crosstalk, and so the ground lines protect the data lines from external interference. It would take a lot of hand cramping work to rearrange a ribbon cable to mimic this arrangement.

  • um.. (Score:3)

    by Beowulf_Boy ( 239340 ) on Saturday November 18, 2000 @09:15AM (#615619)
    Wow, thats, um... neat, yeah, neat....

    Buut seriously, why not just roll the cable , or bend it in half a safe distance from the end?
    Ands how often do you actually get inside your computer? Bout' once a month for me.

    This would help some people though, who work on computers alot, because I have severed wires on computer shrapnel (sharp little corner and crap)

  • What if you're too lazy? (Score:4)

    by Anonymous Coward on Saturday November 18, 2000 @09:16AM (#615621)
    Here's [plycon.com] place that sells them pre-rounded. You can get rounded cables for ATA33, ATA66/100, floppy, and SCSI 50-pin.

  • Cable Impedance (Score:4)

    by uksv29 ( 167362 ) on Saturday November 18, 2000 @09:17AM (#615624) Homepage

    At 66MHz IDE cables are going to look like a transmission line and I assume that is why there are so many earth connections in parallel with the signal wires. If you separate them then you could end up with a mismatch, more RF interference and possibly data corruption.

    If you are going to try it out then backup your data first and make sure that you have a spare cable in case you break something

  • Okay, this would be a problem if any normal user *had* a scanner, a camcorder, a PS2, and six hard drives. As it stands (few can or will shell out that kind of money, especially at $300+ for each of those drives... you're talking about $2000+ in *peripherals*), that's a fairly weak argument for Firewire over ATA/66.

    I'll grant you the technology is damned cool, but the cost is just too high right now.
  • You're right about that (just like SCSI is a luxury... or even a PC, to some extent.)

    But within the next year, a PS2 will not be so far fetched (at least in the average US household), and a scanner at $180 is not too bad either. As a FireWire HD is only about 10% or so more expensive, their value add is pretty decent, for the flexibility. A camcorder, at about $1k, is still a little rich for most of America, but if Sony and Apple had their way, I'm pretty sure a FireWire'd household isn't too far off in the future.

    The nick is a joke! Really!
  • If you're talking SCSI -- you're right. But regular 40pin IDE don't intersect signal and ground. (they should!) Lines 3-18 are DATA0-15. There are only 7 wires used for GND.
    (Google for HWBOOK.PDF [google.com] for more mind-numming details)
    ---
    Inanimate Carbon Rod thanks you for your support. See you in 2004!
  • Folding the cable differs from splitting wires mainly in the time taken, and the chance that you will screw up the cable.

    Cross-talk interference in the cable will increase in both cases, but with IDE this may not be a limiting factor due to error correction.

  • Perhaps. I wasn't so much thinking of purchasing raw cable, but the actual assembly, already made up. Surprisingly inexpensive if you are looking for something that everyone uses.

    The best of both worlds might be to simply figure out the proper length of ribbion cable, accounting for the proper turns to get it out of airflow and where it has to be. Amazing what equipment vendors will put us through to save an extra case or two of flat ribbon. More amazing that we put up with it.

  • Just push the tip of the Exacto knife in between the conductors until it penetrates through the ribbon, then separate the conductors by pushing the DULL side of the knife tip along. This will guarantee that you don't cut into the conductor shielding. You can then either separate the entire length with the dull side of the blade, or just a few inches and do the rest by hand.
  • well, ummm, not really. in the world of digital audio, signal degradation is of utmost importance. wound grouped cables are wound in such a way that they augment signal transfer. Say for instance a 300 foot long snake that runs from the front of house mixing console to the power back stage. millivolt signal distortion happens almost instantaneously when cables are improperly grouped. more relative to this subject would be cat5 for instance. 4 twisted pairs. all isolated, in four pairs which will group the signal over distance. there is an eqaution but don't ask me what the hell it is, because I don't know. In IDE drive cables, the short distance might be a saving grace, but low level signal distortion might me some thing to consider. A thought. :)

  • One more reason (Score:3)

    by John Jorsett ( 171560 ) on Saturday November 18, 2000 @12:43PM (#615636)
    The reason that ribbon cables are flat is to preserve the phase relationships of multiple signals in a cable while at the same time reducing in-cable interference to a reasonable level.

    There's one more reason: it's cheaper. Ribbon cables use insulation-displacement connectors which are gang-crimped onto the cable in one operation. Easy, fast, and reliable. And since very few of us actually care, a manufacturer is going to go with whatever saves money.


  • From what I would assume, flat-ribbon cables are flat for a reason... it helps keep the signals isolated from one another. If you start cramming all those wires together, you wind up changing the impedance and capacitive characteristics of the cable.

    However, I've noticed that the wires on my 86-pin UltraWide cable (came with my Tekram SCSI card) are... well.. interlaced. I originally assumed that it was merely to make the cable more flexible (which it does, nicely), but now that I think about it, might there be another more scientific reason for doing this?

  • Re:You're not using FireWire drives yet? (Score:3)

    by dangermouse ( 2242 ) on Saturday November 18, 2000 @01:40PM (#615641) Homepage
    An 80GB ATA/66 drive is $250. A 45GB drive is $130. The contoller is on my motherboard. Why are you using Firewire drives already?
  • Would'nt this have some interference? I mean it might be flat for a reason. Maybe like the way ethernet cable has 8 wires but only uses 4? Theres a reason for that.

  • Cable Rounding (Score:3)

    by Julius X ( 14690 ) on Saturday November 18, 2000 @09:22AM (#615644) Homepage
    I saw a similar article to this a few months ago, and did it. It's not easy work. An hour or so sitting at my desk carefully splicing these cables with an exact-o-blade isn't exactly fun. I did end up cutting into a couple of the cables, and needed to spend about $15 in new cable, but its not that bad. You just have to be really careful that when you cut into the cable that you hit directly into the groove between the wires.

    But in the end, it all turned out well, and my system looks a lot less cluttered on the inside as a result, and my graphics card temperature dropped by a few degrees (my IDE cables were sitting over my GeForce fan).

    So if you have the patience, go for it. Its definitely worth it I think.

    -Julius X
  • Some ethernet standards actually use all 8 wires (like 100VG... that stuff's neat, doesn't use CDMA in the normal sense).

    Not my field, but I don't think 100VG counts as Ethernet. In place of collision detection, you have a smart hub which tells each station when it can transmit. Ethernet specifically avoids have a central node -- it's all designed around a passive medium shared by cooperating stations. This would be clearer if networks still consisted of fat "ether" cables which served as a simple broadcasting medium, with each NIC actually using a metal spike to tap into it. A modern 10BaseT network may physically resemble a 100VG network, but in many ways its closer to that old clumsy passive cable, especially if you're using passive hubs instead of routers.

    __________________

  • No, no, no! It does *NOT* use 8 wires. Two pairs are set aside for other purposes (voice, etc.) This is the 100BASE-TX specification. There *is* a 100BASE-T4 specification, which uses all 4 pairs, but this is rarely used and is for lower-than-CAT5 cabling.

    http://support.intel.com/support/express/switches/ 10100fast/22421.htm [intel.com] shows that each pair satifies the half of the full-duplex connection.

    --bdj

  • I've done this to *most* of my cables... (Score:3)

    by while ( 213516 ) on Saturday November 18, 2000 @09:29AM (#615657)
    I think the rule of thumb on this one is that you shouldn't try rounding out cables that have stiff wires.

    Floppy cables can be rounded (you can even remove the middle connector), the older IDE cables can be rounded, and 50 pin SCSI wires can also be rounded. Bind everything together at the end with zip ties and then wrap it up with spiral wrap from Radio Shack and similar (e.g. Ax Man in the Twin Cities).

    ATA/66 and 68 pin SCSI cables are a different story. The wires are stiff, and if you don't do the cable exactly right, you have either trashed an expensive cable, corrupted the data on your hard drive. People seem to have mixed success with those.

    If you want to mess with your cables, try some old junky ones, first. If you must use a knife or razor, make the incision as small as possible, then peel the cable apart in opposite directions -- those grooves are the path of least resistance, so it should be more reliable than making a long, perfectly straight cut with a small sharp object.

    If you want rounded cables and don't want to take any risks, I know that Plycon [plycon.com] has all sorts of high quality machine made cables of all types, albeit for a very steep price (just like everything else they sell).

    I'm still not sure why this isn't the standard. Some PC manufacturers have been doing this in their servers and micro towers to improve airflow through the chassis. I'll bet that these kinds of cables eventually become the standard, especially if the cooling requirements for x86 hardware is going to start requiring 1lb. heatsinks like the upcoming P4...

    WARNING: the above comment does not link to goatse.cx [goatse.cx]

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