For testing a retro PC, I bought an old T-9004E Controller PCI IDE (CMD PCI0640B).

My IDE cables have one pin blanked off in the center, whereas this controller presents all pins. I cannot insert my IDE cable without it destroying the central pin.

I have seen something similar on old HP workstations (C3000 rules).

My question is: what is the name/type of the cable I should search for?

Below is the IDE controller connector.

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And below is the modern cable's connector.

enter image description here

As you can see, pin 20 is "covered" in the cable port.

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    Note the "blocked pin" is commonly not massively embedded in the connector. These keys are a separate addition: A small drill and a pull will easily remove it.
    – tofro
    Commented Jan 14, 2023 at 14:53
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    It's trivial to make your own cable with these kinds of IDC headers and a ribbon cable. You can still get them (albeit a bit less easily) from standard suppliers like Mouser or Digikey.
    – Hearth
    Commented Jan 14, 2023 at 22:19

5 Answers 5


I don't think it really has a name. It's still an IDE connector, but when Ultra-ATA/66 came along it changed the cable to the 80-wire cable, and that's when the blocked pin really came along (and also the blue/grey/black color coding)

Anandtech wrote back in 2000:

Also note that while the Ultra ATA/66 specifications calls for a 80 pin IDE cable, only 40 pins are actually used for data and control signals, the second set of 40 pins are paired with the originals and act as ground wires.
While the pin designations remain the same as with regular IDE cables, at Ultra ATA/66 speeds signal quality issues become a major concern. It is due to this fact that your system needs to determine if you are using the newer 80-pin cable, or older 40-pin cable, before it will enable Ultra ATA/66 mode. While the pin designations are the same, as stated above, one of the lines is broken, where in the 40-pin cable, the connection is unbroken. It is this broken connection that the system will pick up on, to determine if you are using the correct 80-pin cable needed for Ultra ATA/66 operation.

So you're still looking for an IDE Cable, but I don't think there's a good name for a "Pre-Ultra-ATA/66 40 wire IDE cable", and almost all of the cables you will find new will be the newer cables since that's been the standard for over 20 years.

You're looking for a cable that has 40 wires, like this, and I think you'll just have to keep searching for IDE cables until you find one:

Old-school 40 wire IDE cable

  • 4
    Yeah. I probably have one of those. One way to get one is to buy really old computers and their hard drive may have such... but over 20 years old computers are not easy to find. Commented Jan 13, 2023 at 18:56
  • For a controller to detect whether a wire is disconnected in a cable, the controller would have to have a pin there. I think the reason for the obstruction is that a 40-pin cable used with non-shrouded connectors wouldn't care if both ends were reversed, but an 80-wire cable would connect the ground wires to the wrong place if it were put in backward.
    – supercat
    Commented Jan 13, 2023 at 20:57
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    Anandtech’s description is incorrect. The missing pin has nothing to do with ATA/66 detection. It’s covered so you can’t use the cable with a motherboard or drive that doesn’t support the cable select feature.
    – Wes Sayeed
    Commented Jan 14, 2023 at 3:50
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    @WesSayeed Can you write it in an answer? Commented Jan 14, 2023 at 12:04
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    I believe it's also possible to make your own cable, since the ribbon cable and the connectors are reasonably standard off-the-shelf parts (IBM did not invent a bunch of custom connectors for the PC) Commented Jan 15, 2023 at 9:30

When I've found myself in that situation I've drilled out the blocked pin (on the cable side). Never had a problem.

  • 2
    Given the choice between drilling out the cable or removing the pin on the device, I'd drill the cable every time. Significantly easier to do, lower risk of unintended damage, and if it were to somehow ruin the connection the cable is much more easily replaced.
    – smitelli
    Commented Jan 15, 2023 at 23:51

Connectors specific to one protocol are a relatively modern thing. In the old days connectors were made by connector manufacturers and then equipment makers bought them and used them as they saw fit. Even today this is the norm for more niche protocols. It's extremely common for the same connector to be used for many incompatible application.

This is a very good thing for retro computing folks, as it means that even long after a system or protocol is obsolete the connectors are generally still readily available.

To reduce the chance of incorrect mating, it was possible to buy variants of female connectors with a hole blocked off and variants of male connectors with a pin missing. For low volume, you could get plugs to fill the holes in female connectors and for male connectors you could pull the unwanted pin out with pliers.

With IDE, a missing/blocked pin was sometimes used as a key to prevent reverse mating with connectors that did not have a shell. However cable manufacturers were not consistent, some cables had the hole blocked, others did not. Apparently controller manufacturers weren't consistent either, with some of them using connectors with all 40 pins present.

Then ATA-66 came along. They needed to improve signal integrity and the way they decided to do it was with custom connectors*. On the mating side, this is the same as a traditional IDE connector. On the cable side the number of wires is doubled. The introduction of special connectors for IDE lead to a much higher level of consistency in the market.

I've always known the style of connector used for older versions of IDE as an "40 way IDC connector". Unfortunately, my experiance with buying connectors is that while many manufacturers make compatible connectors, they all use different names for things, so searching by name is often futile.

What I find does work is going to the website of a supplier, finding the relevant category, using the parametrics to narrow down the selection and then looking through the pictures to find what I want. Be aware that a single picture is often used for a range of components, so it's a good idea to take a quick look at the datasheet when you have found what you think you want, and conversely you should not be put off if the picture shows a different pin count from what you are looking for.

So in this case, I went to Mouser and did a search for "IDC connector", a quick look at the results told me that the relavent category was "headers and wire housings", so I went to that category narrowed down by number of positions (40), pitch (2.54mm), number of rows (2), row spacing (2.54mm) and termination style (IDC). I then sorted by price and the first result was what I was looking for with over 7 thousand in stock.


Fitting IDC connectors to ribbon cables is not too difficult. There are special tools, but honestly i've found a normal vise works just as well.

* The motherboard, master and slave connectors for 80 wire cables all being slightly different, to support cable select and to allow the controller to detect that an ATA-66 cable was in use.

  • FWIW, this (retrofitting IDC connector) is what I did a lot of times in the past for situations like this, and it always worked like a charm. The only things needed are just basic tools for electronics' assembly/disassembly and a bit of patience.
    – user213769
    Commented Jan 15, 2023 at 23:30

This "non-existing" pin is just a key that allowed to position properly the cable. Nowadays, like in your upper photo, you have part of the plastic removed, where the key from the cable goes. It allows you to know which side of the cable should be upper-facing, because otherwise, your keyed-cable wouldn't fit to the socket. Earlier, the cables didn't have such key in the plug, instead of it, they had a missing pin in the socket, or filled one in the cable. Sometimes they didn't have any key, so the cable could be plugged both ways, so you had to properly find the first pin, marked in the cable by red color, and match it to the both sockets. There's nice description of differences between the cables: Upgrading and Repairing PCs: The ATA/IDE Interface

The keyed cable is "80-conductor cable" where the unkeyed one is "40-conductor cable". The 80 one is newer standard of ATA, where the 40 is older, unkeyed one. You should search for "80 conductor ATA cable".

Also worth mentioning, the increase in the conductors in the cable, without changing the pins in the cable is due to the additional conductors being only grounds, used to decrease the interference between signals by inserting the grounded wires between every signal.

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    Thanks but this dont' solve my problem, if I put this cable in the port the pin is ruined and controller is damaged
    – elbarna
    Commented Jan 13, 2023 at 17:20
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    @elbarna The pin is not used on the controller. You can break the pin (e.g. by carefully bending it back and forth using needle-nose pliers) or remove it from the board by desoldering it - making it hot enough melts the plastic of the shell, so it can be pulled) without any functional loss. For practical purposes, removing that pin from the controller makes it more versatile without any downside. The only reason to not remove that pin is to keep the controller in original state as collectors item. Commented Jan 13, 2023 at 19:59

A lot of the cables that I have used just have a plastic pin pushed into the hole. It looks like yours is this style. Take a straight pin and go at it from one of the corners and you should be able to dig the plastic out.
As others have mentioned, the old way to install the cable without the plastic cage around the pins is to find the #1 pin on the board, usually marked with a 1 or and arrow/filled in triangle pointing at pin #1. The number 1 pin on the cable is marked with a red line, squiggles, dots or some other way. Hope this helps.

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