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Two IDE HDs in One Desktop PC
Hi,
Do to very low activity in the "Hardware" NG, I am posting the following he Years ago I had a conversation with a ham radio operator who told me that he had installed two IDE HDs (Hard Drives) in his desktop PC. Before he powered up his PC, he would flip a switch (he installed) to select which HD will boot up. The other is "invisible" to BIOS. Unfortunately, I had no interest in doing what he did, and I do not have a record of his call sign since I don't keep a "Log". Now I have a need to do the same, but I am not sure if "switching" (by a switch) the power source (+5V, +/- 12V and +3.3V) will "work"? In effect, the "unused" HD has it's power cable disconnected, but the IDE data cable is still plugged in. Thank You in advance, John N3AOF |
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#2
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Two IDE HDs in One Desktop PC
Hello John,
Now I have a need to do the same, but I am not sure if "switching" (by a switch) the power source (+5V, +/- 12V and +3.3V) will "work"? Hmmm... I'm not so sure about that being a good idea. Its rather possible that the unpowered electronics on the drive will allow a current to flow thru the datalines causing havock with the wave forms, especially at higher speeds. But have you already tried if simply changing the master/slave setting on both drives will work ? That setting is mostly just the placement/removal of a single jumper, or, if you are unlucky enough, the movement of that same jumper to another position. In the first case it would be a 4-wire thing, with a switch disconnecting one pair of wires (going to a two-pin connector replacing jumper on the first drive), and connecting another pair of wires (going to a two-pin connector replacing jumper on the second drive). In the second case it would be (at most) an 8-wire thing, disconnecting one pair of wires and connecting another pair for the first drive and the same for the second drive. Mind you, I don't think it would be a good idea to flip this switch when the 'puter is powered ... Hope that helps, Regards, Rudy Wieser -- Origional message: wrote in message ... Hi, Do to very low activity in the "Hardware" NG, I am posting the following he Years ago I had a conversation with a ham radio operator who told me that he had installed two IDE HDs (Hard Drives) in his desktop PC. Before he powered up his PC, he would flip a switch (he installed) to select which HD will boot up. The other is "invisible" to BIOS. Unfortunately, I had no interest in doing what he did, and I do not have a record of his call sign since I don't keep a "Log". Now I have a need to do the same, but I am not sure if "switching" (by a switch) the power source (+5V, +/- 12V and +3.3V) will "work"? In effect, the "unused" HD has it's power cable disconnected, but the IDE data cable is still plugged in. Thank You in advance, John N3AOF |
#4
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Two IDE HDs in One Desktop PC
jaugustine wrote:
Years ago I had a conversation with a ham radio operator who told me that he had installed two IDE HDs (Hard Drives) in his desktop PC. Before he powered up his PC, he would flip a switch (he installed) to select which HD will boot up. The other is "invisible" to BIOS. Unfortunately, I had no interest in doing what he did, and I do not have a record of his call sign since I don't keep a "Log". Now I have a need to do the same, but I am not sure if "switching" (by a switch) the power source (+5V, +/- 12V and +3.3V) will "work"? In effect, the "unused" HD has it's power cable disconnected, but the IDE data cable is still plugged in. Switch might be superfluous depending upon the features inside your BIOS. Go into the BIOS and check if there are enable/disable options on the controllers to which the IDE drives are attached. If the IDE drives are attached to *separate* controllers than you may be able to disable one controller and leave the other enabled. That would let you switch between the IDE drives. If the IDE drives are connected to the same controller (as master and slave) then this method won't work -- unless you have another IDE controller (i.e., more than 2 IDE ports on the mobo) to which you could connect the slave drive (then jumpered as a master drive). Switching between IDE ports in the BIOS only works if only one drive (as master) is connected to each IDE controller. Note: Since the IDE drives are found by their BIOS enumeration, you may have to change the boot.ini file so it correctly identifies the new physical enumeration of the slave drive you moved to a different IDE port and made a master. Instead of using the master/slave jumper setup, some IDE drives let you use cable select. So I suspect the guy's physical switch would open or short the CS line on an IDE drive. I doubt he was using a 10-gang switch to manage all 4 power lines on each drive and the cable select on both. Rather than bother with some modified IDE cable and drive jumpering (if your IDE drives support cable select) or having to go into the BIOS to switch which IDE controllers are enabled or disabled (which requires 2 reboots: 1 to go into BIOS and another after changing the BIOS to effect the changes), why not use removable drive bays? Power down and slide in which drive you want to use. The dock remains permanently installed in a drive bay in the case. You need a caddy for each drive. Don't bother with a hotswap dock+caddy since IDE doesn't support hotswap (SATA does). Why go through the bother of all that hardware? Just use a multi-boot manager. Some work by usurping the 446-byte bootstrap area of the MBR (of the master drive). Some want more fancy options than that tiny space allows; however, that means they have to reside within tracks that might be allocated to a partition which means any repartitioning will corrupt that boot manager. In the past, I used GAG The Graphical Boot Manager. It usurps the 446-byte boot code in the MBR of the master IDE drive to present to you a menu letting you select from which drive to boot. Because it was in the MBR, no partitioning changes would affect it (sector 0 of track 1 cannot be assigned to any partition). In fact, if you have a floppy drive, you could setup GAG on a floppy, test a setup, and then later copy it to the MBR to eliminate having to use the floppy. Obviously your BIOS would need to setup to boot from the floppy first. Later, after copying GAG's multiboot manager into the HDD's MBR bootstrap area, you configure the BIOS to boot from the drive (or just not have a floppy in the drive so the BIOS skips it for a boot source). http://gag.sourceforge.net/ You can find several listed at: https://www.thefreecountry.com/utili...managers.shtml All they do is simply change the MBR's partition table as to which partition record is marked as the 'active' partition (which is the boot drive). Way back there was PowerQuest with their utility that all it did was change which partition was marked 'active' in the partition table, you rebooted, and the other drive got used for boot. However, that only worked for when you used multiple partitions on the same disk. GAG will let you boot from any disk (each disk must have an MBR so it has a partition table so a partition record can be marked 'active'). GAG has not been updated in a long time but neither has your hardware and OS. That's what I used back when I had Windows XP and wanted to multi-boot to different versions of Windows (GAG supports other OSes since it is only the bootstrap loader, not the OS boot loader to which GAG will point). Note that a multi-boot manager does not power on/off the disks. All disks will still spin up and which is why you can select from which one to boot its OS. I'm assuming with Windows XP and IDE that your hardware is old which means your motherboard uses a BIOS instead of UEFI. |
#5
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Two IDE HDs in One Desktop PC
wrote:
Hi, Do to very low activity in the "Hardware" NG, I am posting the following he Years ago I had a conversation with a ham radio operator who told me that he had installed two IDE HDs (Hard Drives) in his desktop PC. Before he powered up his PC, he would flip a switch (he installed) to select which HD will boot up. The other is "invisible" to BIOS. Unfortunately, I had no interest in doing what he did, and I do not have a record of his call sign since I don't keep a "Log". Now I have a need to do the same, but I am not sure if "switching" (by a switch) the power source (+5V, +/- 12V and +3.3V) will "work"? In effect, the "unused" HD has it's power cable disconnected, but the IDE data cable is still plugged in. Thank You in advance, John N3AOF The ATA/ATAPI spec has "DC characteristics" as well as three appendices of interesting info. Frequently, appendices can fill in the gaps, where dry specsmanship does not. http://t13.org/Documents/UploadedDoc...TA-ATAPI-6.pdf Rudy has already hinted at the electrical issues, in his answer. We had a succinct term for the I/O type required in your application, at my work. We would write "this I/O needs to be fail safe on power loss". Such a specification meant, if you lost +5V on a chip, the I/O were not allowed to clamp the I/O bus to ground. The I/O bus was to remain open circuit on power loss. This helps prevent stuff from getting burned or reducing predicted device life. In modular power situations (each subsystem has its own power supply), you have to plan for these kinds of scenarios. What if the power goes off ? What happens ? In a normal implementation, you put "up" and "down" clamp diodes to the rails on the receiver. If you kill +5V, it is assumed the upper diode pulls the I/O bus to ground, drawing excess current from the driven end. (IBM used to put "up-up-up" "down" clamps on their stuff, but I don't know if the intent was to reduce the possibility of failsafe accidents or not. The three "ups" there, refers to three diodes in series for a top-side clamp.) On a failsafe driver, you remove the upper clamp diode. That's one way to do it. I don't know any more details about it than that. It was generally very hard to get full analog models from the silicon fab (even from our own fab!), to verify behaviors like this. I got one model from the twits in our fab, where the person doing the extract "forgot" to put in the clamp diode model (the front end of the pad was missing). Rendering the model file a pile of garbage. It's even harder to work with third parties to get models (as the model file exposes process information about their fab). I tried using keywords such as "failsafe fail safe, hot plug, hot insert" but cannot find any good detail for "ATA/ATAPI IDE parallel ATA" and so on. So I cannot confirm any I/O characteristic other than the "DC Characteristic" section of the above spec. ******* It's easier to deny your request, for another reason. The other issue, is signal integrity. Host -------+---------+ OK, no bad stub for reflections | This works better than the second config. drive Host -------+---------+ Still good. Design intent. | | (Signals on this crap are never pretty! drive drive The spec has sample 'scope-like pictures...) Host -------+---------+ You're not supposed to do this. | (Reflections off cable stub on end) drive So if you were to switch power, you'd only switch power on the middle drive, not the end drive. And you'd still be left with the issue of what DC effect the I/O has, caused by an unpowered drive. Either there's the electrical load of a series damped 82 ohm resistor on ground. Or... something. ******* And, you can find some corny info, regarding hot swap of IDE. http://www.overclockers.com/forums/s...rive-Enclosure "According to the manual this enclosure will only hot-swap in Windows 98/98SE. There is a reason you do not see IDE hot-swap drives. The IDE interface and Windows was not designed for it." There is the issue of "drive detection", if you actually powered up a drive while the OS was running. Similarly, you'd have the issue of detecting a drive went missing. (Does IDE offer "Safely Remove" ? I think not!). So what the hell does Win98 have to do with this ? Puzzling... Does Win98 assume both drives are present at all times, and "test" before using them each time ? ******* SATA is designed from the ground up, to support all of this stuff. Hot insertion. It has advanced contacts on the connector, so power/gnd pins touch before data pins. The pin staggering only works right, in a backplane scenario. You're on your own, in terms of connector capture issues (tipping the connector while inserting it, if you do it manually in your tower case). There are some combo power+data connectors, where you'd want to be careful of connector capture while using them. I can't be sure the tolerance analysis was done for that usage model. If your power and data cables are separate, the sequence can be made a bit safer. ******* And if you are going to try stuff like this on IDE, use a separate I/O card. Like a VIA combo SATA/IDE card for example. If you blow the I/O while screwing around, it means your motherboard remains intact. The VIA chip could be damaged, but the damage tends not to propagate from chip to chip on failures. I realize hot-swap enclosures were available for IDE, but I could never trace down any authoritative reviews or get usage info, to prove they actually worked, and worked without corrupting anything. Whether they were intended for (unpowered) swapping or whatever. The adverts always made it seem you could do anything you want. https://www.evertek.com/viewpart.asp?auto=2120 "Hot swappable (please see note below) # Notes: # Works in any OS - hot swap features only work in Windows 98/98SE " Usage cases to consider: 1) Normal operation. "DC Characteristics", combined with the recommended cable config (don't do diagram #3) applies. The stuff we rely on to work, is in the spec. 2) Remove power from chip, chip pulls to ground. Is the IDE pad I/O failsafe ? No proof in as many words. There is one reference in the T13 spec to providing an "advanced ground" which implies the I/O is fail safe, but that is pretty thin evidence indeed. If the I/O wasn't fail safe, it would have said "advanced power/ground" instead. Other parts of the spec show clamp diodes (naughty). 3) Hot swap/hot plug. Are dynamically added IDE devices detected? Are dynamically removed IDE devices detected? Does pulling a sled, corrupt actively occurring data transfers? The existence of hot-swap enclosures clouds this issue quite a bit, due to a lack of historical artifacts of usage. All I can tell you, is I know what I *won't* be doing :-) Paul |
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Two IDE HDs in One Desktop PC
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Two IDE HDs in One Desktop PC
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#8
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Two IDE HDs in One Desktop PC
SNIP
Now I have a need to do the same, but I am not sure if "switching" (by a switch) the power source (+5V, +/- 12V and +3.3V) will "work"? In effect, the "unused" HD has it's power cable disconnected, but the IDE data cable is still plugged in. Thank You in advance, John N3AOF I used to do that all the time. I had one drive with DOS 6.3 on it and one with XP (W98 before that). The DPDT switch is just to select which one is master. (and showed up as C: to boot) Because the DOS was FAT and the XP was NTFS, XP could see both drives but DOS could only see one. Newer BIOSes allow selective booting so that is not necessary anymore. You can set a prompt select which drive you want to boot. I have DOS on a thumb stick in this machine now. Hi, I should have given more details why I wanted this. I want TWO "C:" drives (one or the other is "disabled"), You can't have it that way with a Master and Slave configured HDs unless you can switch in BIOS settings, which one is Master and which one is Slave. The BIOS settings in my PC has NO feature for Enabling one HD and Disabling the other. John |
#9
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Two IDE HDs in One Desktop PC
wrote:
SNIP Now I have a need to do the same, but I am not sure if "switching" (by a switch) the power source (+5V, +/- 12V and +3.3V) will "work"? In effect, the "unused" HD has it's power cable disconnected, but the IDE data cable is still plugged in. Thank You in advance, John N3AOF I used to do that all the time. I had one drive with DOS 6.3 on it and one with XP (W98 before that). The DPDT switch is just to select which one is master. (and showed up as C: to boot) Because the DOS was FAT and the XP was NTFS, XP could see both drives but DOS could only see one. Newer BIOSes allow selective booting so that is not necessary anymore. You can set a prompt select which drive you want to boot. I have DOS on a thumb stick in this machine now. Hi, I should have given more details why I wanted this. I want TWO "C:" drives (one or the other is "disabled"), You can't have it that way with a Master and Slave configured HDs unless you can switch in BIOS settings, which one is Master and which one is Slave. The BIOS settings in my PC has NO feature for Enabling one HD and Disabling the other. John You realize those can be added to the boot.ini on the "BIOS-preferred" drive, right ? The boot.ini includes an ARC path. The ARC path has a disk number field, which means the BIOS boots drive #1, but a reference in boot.ini can point to drive #2. What you need then, is for the OS to put up the boot manager. The boot process starts with drive #1. Then, in the menu, you see the boot choices. You select the second one, and off it goes to drive #2. EasyBCD makes this easy for Vista+ computers. A text editor makes boot.ini easy for a WinXP or Win2K computer :-) Plus or minus some attribute bits ("attrib" command) on an NTFS partition. FAT32 partitions would make this part easier (no permissions to worry about). This works for relatively static situations, like drive #1 and drive #2 are always left in the computer. Both drives have data content storage, giving an incentive to not remove them. If you add drive #2 to the boot.ini on drive #1, it doesn't prevent drive #2 from being use by itself for boot purposes. And there's a good chance drive #1 is not going to be checking for drive #2, when the boot.ini is being used. Only if you actual select drive #2 in the WinXP boot menu, and it doesn't exist, will it get upset. I discovered the other day, that Win10 is not as happy about that. I have two Win10 OSes on the same hard drive, and both OSes share the same BCD file (for boot menu purposes). If the second partition goes missing, the boot stops and complains. Not what I was expecting. I'd done a disk2vhd on the hard drive, and not selected capture of the second C: partition, and the boot process noticed and bailed on me when I tried to use the VHD later in Virtualbox. The BCD tends to use GUID identifiers, rather than an ARC path, and that may have played a role in the failure. But you should be quite safe to edit the boot.ini and add the line to it, from the other drive. Making sure that your ARC is actually correct. You can probably find some examples around, of multi-boot mods. http://best-windows.vlaurie.com/boot-ini.html https://docs.microsoft.com/en-us/win...-boot-ini-file With respect to "rdisk", the BIOS will probably assign the BIOS booting drive "rdisk(0)" and consequently, the non-BIOS boot choice you're trying to add (to the OS menu), will have some other rdisk number, like maybe rdisk(1). Paul |
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Two IDE HDs in One Desktop PC
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#11
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Two IDE HDs in One Desktop PC
On Fri, 22 Sep 2017 12:42:28 -0400, Paul
wrote: wrote: SNIP Now I have a need to do the same, but I am not sure if "switching" (by a switch) the power source (+5V, +/- 12V and +3.3V) will "work"? In effect, the "unused" HD has it's power cable disconnected, but the IDE data cable is still plugged in. Thank You in advance, John N3AOF I used to do that all the time. I had one drive with DOS 6.3 on it and one with XP (W98 before that). The DPDT switch is just to select which one is master. (and showed up as C: to boot) Because the DOS was FAT and the XP was NTFS, XP could see both drives but DOS could only see one. Newer BIOSes allow selective booting so that is not necessary anymore. You can set a prompt select which drive you want to boot. I have DOS on a thumb stick in this machine now. Hi, I should have given more details why I wanted this. I want TWO "C:" drives (one or the other is "disabled"), You can't have it that way with a Master and Slave configured HDs unless you can switch in BIOS settings, which one is Master and which one is Slave. The BIOS settings in my PC has NO feature for Enabling one HD and Disabling the other. John You realize those can be added to the boot.ini on the "BIOS-preferred" drive, right ? The boot.ini includes an ARC path. The ARC path has a disk number field, which means the BIOS boots drive #1, but a reference in boot.ini can point to drive #2. What you need then, is for the OS to put up the boot manager. The boot process starts with drive #1. Then, in the menu, you see the boot choices. You select the second one, and off it goes to drive #2. EasyBCD makes this easy for Vista+ computers. A text editor makes boot.ini easy for a WinXP or Win2K computer :-) Plus or minus some attribute bits ("attrib" command) on an NTFS partition. FAT32 partitions would make this part easier (no permissions to worry about). This works for relatively static situations, like drive #1 and drive #2 are always left in the computer. Both drives have data content storage, giving an incentive to not remove them. If you add drive #2 to the boot.ini on drive #1, it doesn't prevent drive #2 from being use by itself for boot purposes. And there's a good chance drive #1 is not going to be checking for drive #2, when the boot.ini is being used. Only if you actual select drive #2 in the WinXP boot menu, and it doesn't exist, will it get upset. I discovered the other day, that Win10 is not as happy about that. I have two Win10 OSes on the same hard drive, and both OSes share the same BCD file (for boot menu purposes). If the second partition goes missing, the boot stops and complains. Not what I was expecting. I'd done a disk2vhd on the hard drive, and not selected capture of the second C: partition, and the boot process noticed and bailed on me when I tried to use the VHD later in Virtualbox. The BCD tends to use GUID identifiers, rather than an ARC path, and that may have played a role in the failure. But you should be quite safe to edit the boot.ini and add the line to it, from the other drive. Making sure that your ARC is actually correct. You can probably find some examples around, of multi-boot mods. http://best-windows.vlaurie.com/boot-ini.html https://docs.microsoft.com/en-us/win...-boot-ini-file With respect to "rdisk", the BIOS will probably assign the BIOS booting drive "rdisk(0)" and consequently, the non-BIOS boot choice you're trying to add (to the OS menu), will have some other rdisk number, like maybe rdisk(1). Paul A switch on the drive jumpers is easier. |
#12
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Two IDE HDs in One Desktop PC
SNIP
Now I have a need to do the same, but I am not sure if "switching" (by a switch) the power source (+5V, +/- 12V and +3.3V) will "work"? In effect, the "unused" HD has it's power cable disconnected, but the IDE data cable is still plugged in. Thank You in advance, John N3AOF I used to do that all the time. I had one drive with DOS 6.3 on it and one with XP (W98 before that). The DPDT switch is just to select which one is master. (and showed up as C: to boot) Because the DOS was FAT and the XP was NTFS, XP could see both drives but DOS could only see one. Newer BIOSes allow selective booting so that is not necessary anymore. You can set a prompt select which drive you want to boot. I have DOS on a thumb stick in this machine now. Hi, I should have given more details why I wanted this. I want TWO "C:" drives (one or the other is "disabled"), You can't have it that way with a Master and Slave configured HDs unless you can switch in BIOS settings, which one is Master and which one is Slave. The BIOS settings in my PC has NO feature for Enabling one HD and Disabling the other. John The master and slave is a jumper on the drive. If you replace the jumper with a switch, you can switch master and slave by flipping the switch. Use a DPDT and you can swap them with one switch. You will need to power down and back up to make that work because it determines the setting in POST. Hi "gfretwell", I know about the jumper on a HD. Default is for CS (Cable Select). Only when the PC is shut off, would I flip the switch to "swap" HDs as Master and Slave. Perhaps this is the method the "ham" I had a conversation with some time ago used. Thanks again, John |
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Two IDE HDs in One Desktop PC
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#14
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Two IDE HDs in One Desktop PC
Mike,
Plugin drive system should be cheap. They could be. But you don't want the cheap(est) ones. I bought a number of such disk bays and caddies (so I could multi-boot without worrying about if the used OS would keep its fingers off of the multi-boot sofware (*coff* MS *coff*) ), but quite soon started having lots of troubles with getting the 'puters to start -- which instantly disappeared when I connected the drive(s) directly to the cable. In other words: buy a few *good* (and thus most likely more expensive) ones. Regards, Rudy Wieser -- Origional message: "mike" wrote in message news On 9/22/2017 3:53 AM, wrote: SNIP Now I have a need to do the same, but I am not sure if "switching" (by a switch) the power source (+5V, +/- 12V and +3.3V) will "work"? In effect, the "unused" HD has it's power cable disconnected, but the IDE data cable is still plugged in. Thank You in advance, John N3AOF I used to do that all the time. I had one drive with DOS 6.3 on it and one with XP (W98 before that). The DPDT switch is just to select which one is master. (and showed up as C: to boot) Because the DOS was FAT and the XP was NTFS, XP could see both drives but DOS could only see one. Newer BIOSes allow selective booting so that is not necessary anymore. You can set a prompt select which drive you want to boot. I have DOS on a thumb stick in this machine now. Hi, I should have given more details why I wanted this. I want TWO "C:" drives (one or the other is "disabled"), You can't have it that way with a Master and Slave configured HDs unless you can switch in BIOS settings, which one is Master and which one is Slave. The BIOS settings in my PC has NO feature for Enabling one HD and Disabling the other. John I did a lot of experiments with dual hard drives. Gave up after about the 10th time a linux update trashed the windows boot. Simple solution is plugin hard drives. You can't trash a drive that's not plugged in. Sounds like you have IDE hard drives. Plugin drive system should be cheap. |
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