40 Pin IDE Cable Question - Page 1
Forum section: electronics / projects

author: bostonman
author_rank: Super Contributor
timestamp: May 03, 2023, 04:47:33 pm
content: I know IDE cables are typically keyed with an external tab, but I have an oscilloscope where I'm using an IDE to SATA converter for the SSD, and the converter doesn't have a socket with a key slot.My current IDE cable has one hole plugged which allows for correct connections and not accidentally reversing it.The IDE cable is failing so I want to purchase a new one, but I'm finding most IDE cables don't have this hole plugged and rely on the external tab; or I'm finding them to be expensive. Some also advertise "80 wires", and I believe this may be within the ribbon cable where all 80 wires are parallel and doesn't matter for functions (If they are dual ribbon cables, I may run into space issues).Does a specific name/type exist that I should search for in order to get one with the hole plugged? I can insert something myself (glue), but wanted to check on naming convention.

author: wasedadoc
author_rank: Super Contributor
timestamp: May 03, 2023, 04:54:48 pm
content: Have you considered making your own cable? The IDC Insulation Displacement Connectors and 40 way ribbon cable are readily available. Advantage is that you can get the exact length needed.

author: bostonman
author_rank: Super Contributor
timestamp: May 03, 2023, 04:57:29 pm
content: Not a bad idea.Length isn't necessarily an issue (ignoring too long may cause delays), but more about bulk. If "80 wire" is two 40-pin cables stacked, then that could be an issue.

author: magic
author_rank: Super Contributor
timestamp: May 03, 2023, 05:00:38 pm
content: The so-called 80 conductor cable has 40 extra ground wires inserted between the signals to reduce crosstalk and maybe control wave impedance better. It uses a denser ribbon of the same overall width. It was necessary for the fastest transfer modes but it should be compatible with older systems too. Connector pinout is the same.

author: jpanhalt
author_rank: Super Contributor
timestamp: May 03, 2023, 05:01:44 pm
content: I bought a string to those plugs/keying pins from Digikey years ago. Surprisingly expensive considering what they are.

author: bostonman
author_rank: Super Contributor
timestamp: May 03, 2023, 05:08:46 pm
content: I'm also finding them to be expensive, but prices are all over the spectrum.Although I'll probably never need these again, often times I find it best to order extra quantities just in case since I'm already paying shipping.Why do some IDE cables have one hole blocked and others don't? Is it just by choice or does a specific name exist?

author: mariush
author_rank: Super Contributor
timestamp: May 03, 2023, 05:09:37 pm
content: You can buy ide cables off eBayhttps://www.ebay.com/itm/255620555381https://www.ebay.com/itm/274553744014https://www.ebay.com/itm/280862414714(round)yes you could buy the idc connectors and ribbon cable, but often it will cost you more.The blocked hole acts as a key, to prevent reverse insertion ... some older hardware doesn't have that pin broken off but relies instead of the plastic shroud around the pins to act as key, in which case having the hole filled in the cable connector would prevent you from inserting the cable.

author: jpanhalt
author_rank: Super Contributor
timestamp: May 03, 2023, 05:10:37 pm
content: I didn't find them easily on DigiKey. The ones I got were white. Here is a source for black ones:http://www.frontx.com/pro/cpx079.htmlI guess they are a niche product and hence expensive. My thought was to use a toothpick.

author: bostonman
author_rank: Super Contributor
timestamp: May 03, 2023, 05:18:36 pm
content: Should I be concerned over 18" versus 24"?Most likely I can use the first plug since I don't need both, which will shorten the distance from the motherboard to the drive.

author: magic
author_rank: Super Contributor
timestamp: May 03, 2023, 08:48:42 pm
content: 18" is the maximum recommended by ATA specs. Do you really need more?Leaving unterminated stubs is apparently not recommended either, so connect a single device at the end of the cable. Maybe less of an issue with old/slow devices.https://www.rigacci.org/docs/biblio/online/ide_modes/conf_Cable.htm

author: bostonman
author_rank: Super Contributor
timestamp: May 04, 2023, 02:32:23 am
content: QuoteThat was actually my point on whether it's even worth getting 24" since the eBay listings are 24".Unfortunately I don't have room to connect something to the unused connector.

author: mariush
author_rank: Super Contributor
timestamp: May 04, 2023, 05:51:54 am
content: You can get shorter cables from eBay - do I even have to tell you? Like you can't figure something like this yourself?For example :https://www.ebay.com/itm/255625173297(1 device cable, 4" long, 40 wire, no key)orhttps://www.ebay.com/itm/255625297700(1 device , 13" long, 40 wire)orhttps://www.ebay.com/itm/325427523277(2 device cable, 16" long, 40 wire)and so on.... I just added "short" to "ide cable" in my ebay search.Modern hard drives have much better signal processing compared to older drives, so they won't be that bothered by a few extra inches of ribbon cable.But a drive should work just fine connected to the middle connector, unless your ide to sata always expects the drive to be configured as MASTER.If you connect to middle connector, you may have to configure your drives as SLAVE instead of Master (default) or set it to Auto (cable select or CS) - often just an issue of moving a jumper on the drive one position, but otherwise it should work without any issues.

author: tooki
author_rank: Super Contributor
timestamp: May 04, 2023, 12:37:14 pm
content: Quote from: magic on May 03, 2023, 05:00:38 pmFYI, the IDC side of the connector, however, is very specialized, since it internally connects the ground wires to the correct ground pins of the ATA standard. So if making your own cable, you’d have to make sure it’s the special 40-pin/80-wire ATA connector, not an ordinary 40-pin IDC ribbon connector.

author: tooki
author_rank: Super Contributor
timestamp: May 04, 2023, 12:38:12 pm
content: Quote from: bostonman on May 03, 2023, 04:47:33 pmWouldn’t it be easier to just cut in the keying slot?

author: The Doktor
author_rank: Regular Contributor
timestamp: May 04, 2023, 02:11:58 pm
content: Quote from: tooki on May 04, 2023, 12:38:12 pmOr just plug the appropriate hole on the new cable with epoxy? Better yet, just mark the new cable & socket and pay attention when plugging them in.

author: bostonman
author_rank: Super Contributor
timestamp: May 04, 2023, 02:23:02 pm
content: QuoteThat wasn't what I meant. My question was regarding whether 18" or 24" makes a difference, and, also, many cables I saw with the plugged hole (or lower cost) are 24". My initial question was regarding whether an IDE with a plugged hole versus one without has different names and/or whether buying one or the other may not provide diversity should I ever need these in something else.QuoteThis has been my plan, but thought I could save myself the trouble and locate the correct one since I'm buying them anyway.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: May 04, 2023, 02:53:06 pm
content: For those of us who are old enough to remember building PCs in large tower cases, a 24 inch IDE cable from the mobo to the CD or HDD was not uncommon. ( Their width made them an obstruction to air flow ). So I assume in typical PATA/UDMA modes, length is not an issue here.RTFM :https://en.m.wikipedia.org/wiki/Parallel_ATA

author: pcmad
author_rank: Regular Contributor
timestamp: May 05, 2023, 04:51:23 pm
content: older 40 Pin IDE Cable Question on pc was not keyed pre 2000s and i have many time put a hdd or cd the wrong way round and it not not damage anything