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.
SO .. Does anyone know of a reasonable way to "mount" IDE internal HDs & CDROMs externally?
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Use the same circuit the external USB/Firewire boxes use. It converts USB and/or Firewire to IDE. You probably need a dedicated cisrcuit for each drive. Then you can use a USB or Firewire cable to connect to your PC. The drives can even be hot-plugged (is four power-supply allows).
You can still get removable IDE drive cases "caddys" where you mount a 3.5" drive in a 5.25" case. Some of these are hot-swappable although that does depend on which OS you are using...
That would work for the hard discs. CD-ROMs are more problematic: USB or Firewire as others have suggested would probably be best. Try googling for hot swap cd drive.
Please note there isn't really any such thing as an "internal" IDE/ATAPI device --- they're all internal by definition. The only question to decide upon is "internal to _what_?" The design assumes a PC or something like it, but there are alternatives, most prominently in the form of separate boxes that hold an ide drive and connect it to something else.
The big problem is an electrical one: IDE/ATAPI is not at all designed to be hot-swappable, and not particularly friendly with the concept of external mounting. Note that there's not even a standardized plug for external IDE cables --- the allowed cable length of about 80 cm (40 cm in some cases) would make any non-neglible amount of external cable a fragile concept anyway.
My recommendation would be to forget about using IDE itself as the attachment method for those movable drives. Use USB, Firewire, or ethernet instead.
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Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.
Alas, there are several problems with using any other attachment than IDE for the drives I want to use: 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.
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
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.
I have, in each of the four rackmount chassis that I have, installed removable HD carriers 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 then problematic. I suppose 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.
The removable HD sleds connect to their frames with just 50-pin Centronix connectors which carry both the normal 40-pin complement of IDE signals and the power and ground. I've tried using a commercial SCSI cable to allow one of the sleds to be external to 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.
Well it is possible to create a Boot ROM for network cards so it could boot off a remote system via Ethernet and the ethernet can be supported under DOS. Boot ROM could detect if the controller has a physical link to establish if it should carry on or relinguish control back to the BIOS to boot harddrive(s).
USB can be supported under SOME newer DOS variants (as used by Norton Ghost).
Ethernet would be easier and cope with longer distances.
That is extra support and back configuration that may be awkward.
WHY??
Why put a SCSI cable onto a connector configured to drive IDE/ATAPI? You may have exceeded distances for drive, let alone the fact that the interfaces could be wired differently so ground/power commoning could mess up the signals. Also the power may have been going down insufficient conductor size causing power drops.
I am pretty sure it is because you used lipstick as superglue.
At one site several years ago a class was setup for doing imaging training and to ensure the students did not load any nastys, I made up for the customer several cables to take the floppy interface from the motherboard to a connector mounted on a blanking plate. Added to the cable several power and ground conductors. Then made a box with a floppy drive and a SHORT cable to a connector. This way at the time any boot/driver floppies could be loaded by the administrator.
If the following conditions can be met
1/ CD-ROM is the ONLY device on the secondary IDE interface, AND 2/ all your motherboards have Primary AND SECONDARY IDE interfaces, AND 3/ At least one spare slot on ALL target systems within SHORT distance from SECONDARY IDE interface connector
Then consider making a SHORT internal cable to blanking plate connector of many pins, with MANY pins also assigned to take the power and ground. Get a USB 5.25" USB CDROM empty case, and modify it to take a cable to mate with the other connector as 1-1 connection all separate wires. Make the cable SHORT to keep the distance of cable less than a normal IDE cable length about 14inches or less.
CDROM will always be behind the unit, ensure the unit will be supported and not hanging on the cable, or make a bracket to hold the CDROM box.
If necessary use 50pin Centronics connectors I am sure you could probably buy pre-punched blanking plates that will take a 50pin Centronics connector. You only need a couple for the box end (keep a spare or two), and at least one of the opposite type for the computer ends
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DOS doesn't have to. Modern BIOSes can, at least in principle, boot off just about any USB device that reports itself as a harddisk. Some people have been known to keep a Linux system image on digital cameras or MP3 players, just for the perverse fun of it...
That's not particularly much harder with a disk mounted in an external USB box than with one mounted in a IDE quick-switch carrier. Rip the HD out of the box, put it into your PC as a secondary, and that's that. For Linux, you can even leave it in the box -- just attach it and install Linux onto it.
At least for Linux, I must object to this statement. Linux (given the right distribution) installs onto pretty much anything you want, if you know a bit more than how to do the three mouseklicks for the vanilla default installation.
What's stopping from building those cables yourself?
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Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.
I haven't been able to find any 50-pin Male and Female Centronix IDE connectors. Since I have a medical problem with my hands, I'm not likely to succeed in using solder-cup connectors -- IDE are a must. If you know of a source, I'd be very grateful.
The things you're talking about here are not "IDE connectors" --- they're just plain old press-on connectors for ribbon cable. I doubt such connectors exist in Centronix form --- the pitch of those plugs would appear too different from standard ribbon cable.
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Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.
The Centronix style IDC connectors do exist. I haven't looked for a 50 pin version but if they are done at that number of pins then I am sure they should be findable. Try Farnell, RS or your local decent electronics suppliers. I have the standard printer Centronix plugs in IDC style plugged into my printer at present.
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