Externally connecting internal IDE dives -- Redux

Here's my original posting

============ OP ============= I have a very large and complex rack-mounted box which contains a 14-slot ISA bus passive backplane [physically divided into 2 separate PC segments] and 12 cards of various sorts installed. The box has physical room for mounting 3 drives in the front opening in which I have a floppy and 2 removable HD frames for one of the PC's and I have internally mounted a permanent HD and made a cutout in the back panel for a floppy for the second PC in the box. Everything works well ... Until I need to attach a CDROM drive to one of the PC's. Currently I've got the cables from the secondary IDE controllers and a power cable hanging outside the box and I simply hang a CDROM drive (or a temporarily needed HD) from the cables. That's ugly and, even though it's a very low traffic area, still quite unstable and probably unsafe as well. =================

Some people have helpfully suggested using an attachment method other than IDE to accomplish what I want to do. Alas, there are several problems with using any other attachment than IDE for the drives I want to use.

Here's additional background: 1. I have to be able to boot and run a variety of OS on each of the computers including standard MS-DOS which doesn't (natively) support USB, Firewire, or Ethernet. As a general rule, if I need to attach something external, it has to be IDE here.

  1. I have to be able to (re)install OS like Linux and Windows onto the actual removable drives that are housed in the drive carriers. Neither of these OS installation programs support USB or Firewire. Ethernet to another PC on the network is possible, though not necessarily easy nor reliable
  2. I'm not looking for hot-swappability, but simple reconfigurability from time to time for almost exclusively attaching a CD-ROM drive -- though on a very few occasions I've needed to attach a secondary HD so I could do a drive copy.
  3. Finally, regardless of the availability of alternate technologies, assume that for a variety of reasons I _must_ connect IDE devices which are normally mounted internally in an external manner. If for no other reason, it's the only way that seems to work consistently across the range of OS & uses I have.

In each of the four rackmount chassis that I have, I've installed removable HD carriers for the regular drives and have several (boot) drives for each computer that simply slip in and out [with power off, of course]. This takes care of the basic HD's, but attaching a CD-ROM drive from time to time is problematic. I could install a SCSI card in each box and use an external SCSI CDROM drive I have, but I don't always want to have SCSI part of the computer configuration because I'm trying to match the exact setup of various embedded systems for which I've developed and for which I write and maintain software. Also, MS-DOS doesn't (easily) support SCSI without additional drivers which can wreck the memory configuration I'm trying to preserve.

One solution I've tried is the following: The removable HD sleds I use connect to the frames with 50-pin Centronix connectors which carry both the normal 40-pin complement of IDE signals and the power and ground. In an attempt to extend this outside of the box so I could use an internally mounted drive sled frame with an external sled, I've tried using a commercial SCSI cable to connect a sled outside the frame but the computer wouldn't boot with it installed and I'm pretty sure it's because the cable manufacturer is taking shortcuts and running fewer than 50 wires by using a common ground wire or two in place of the several in the normal SCSI configuration. I haven't been able to find any compatible cables made with ribbon cable where I could be guaranteed of 50 separate wires. If anyone knows of a source of 50-wire ribbon cables with one each male and female 50-pin Centronix connectors, I'd be very grateful because I think that this would solve my problem.

Norm

Reply to
Norm Dresner
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The total cable length from controller to drive needs to be 18" or less.

I think that rules out any "solution" based on pure IDE.

That's why you got suggestions of alternatives.

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Reply to
CJT

Whole posting snipped.....

One thing you might look at is a set of ide-to-scsi adapters, then use scsi cables for hookup. These adapters plug right on the back of the ide drives.

formatting link
is one example.
formatting link
is another. Scsi drives *should* boot natively from dos, windowd, and linux (mine do), as the bios in the scsi adapter card kicks in before the os boots.

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Reply to
Dan Major

Okay, I'll agree that there is some sort of cable-length limitation, but I've got several PC's of various manufacture which are running (apparently) perfectly well for years with 24" and 36" IDE cables so the 18" limitation isn't a brick wall.

I've tried putting a removable frame inside the box with a "SCSI" 50-pin Centronix cable dangling out which I plugged into a drive sled. As I mentioned earlier, the PC simply won't even start to boot this way which is undoubtedly due to the cable not being a 50-wire cable. If I could find a short -- maybe 12" -- 50-wire ribbon cable with 50-pin male and female Centronix connectors, I could certainly create a total cable less than 18". But so far I've failed to find any 50-wire ribbon cable with M&F connectors of any length.

It looks like I'm stuck -- at least for the present -- with having the secondary IDE cable dangling outside the box. That does work, reliably. But it's not safe with me around the equipment ;-))

Norm

Reply to
Norm Dresner

You could make your own pretty easily.

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Reply to
CJT

Um... they only have 24 & 36 pin versions

YEAH! That looks exactly like what I need.

BTW, I have the hand tool for assembling them. Got it because I ruined too many using my hands!

Thanks Norm

Reply to
Norm Dresner

(apparently)

limitation

is

a
18".

connectors

Until very recently -- previous response from Rich Grise -- I didn't have a source for the connectors. But now I do and I'm going to order them.

Norm

Reply to
Norm Dresner

less.

but

the

50-pin
I

which

could

and

less

with M&F

the

reliably.

I

They're really _not_ Centronics, which has 36 pins. They're Amphenol connectors, which might lead you to a more productive search. These are used on telco cables, on SCSI cables, and various types of ribbon cables. Hope that helps.

Reply to
Watson A.Name - "Watt Sun, th

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