Switching a 40-pin IDE cable

[rube the noob]

Hi guys,

I am dreaming of a switch on the front of my 'puter so that I can choose between two hard drives when I boot up. (selected before the power is on, not on-the-fly.) I need to be able to switch the 40 pin IDE cable and the power. I have seen from Google-ing that the power has been done with a DTDP switch, but I have not seen an IDE switch (that is cheap). I wonder if one could use a simple circuit to switch them.

I have some left over ribbon cables and 40 pin female sockets that I could put to work. What would be the best chip(s) to use for the switching?

Also, where should I look to find this info myself? Are there sites that describe the function of various families of chips?

Thanks!

Rube

[Carl-NC]

Do you really need to switch the 40 pins? I think the power is all you need to switch.

[rube the noob]

I thought I read that there would be "ghosting" from the unpowered hard drive. Since I can't find that reference or anything like it, I am going to try it out. I'll report back how it works! (if I still have a computer)

Rube

[Seeker]

Hi Rube, if your PC have not "hotswap" function you can destroy motherboard and HDDs, when power on or off on HDD. If this is IDE bus , I am sure that function does not exist.

[rube the noob]

Thanks seeker,

I am not planning on switching them while the computer is on. What I am seeking is essentially a way to unhook the power and IDE cables on one drive and plug them into the other. I just want to do that via a handy switch on the panel.

Carl,

It doesn't work to just switch the power, for me anyway. The master/slave settings appear to be what is causing problems. Others have been able to sort of make it work by utilizing the order the devices are installed on the cable, but it isn't elegant. Also you can change the jumper settings by using a second switch, but I wanted to keep my existing slave hard drive. I just want to change my primary. After more research, I am concerned that an electronic switching mechanism for the IDE cable might cause problems, since the electrical signals seem so delicate.

[Carl-NC]

Many years ago I swapped between 2 hard drives, and all I did was move the power plug to the active drive. They were both set to primary, and both on the data cable.

[rube the noob]

I'll double check. Maybe I have something else wrong.


Unfortunately I am now obsessed with finding out what chip would be best for switching. It seems like the simplest thing you could possiby do in digital electronics. The fact that I can't find anything out about it makes me feel small and inadequate. Is it so simple that no one needs to talk about it? Before I started, I assumed there was some 74-something chip that would be perfect, and a quick search would yield said chip. It would be a simple matter to grab a bunch of them and use one of the five volt lines to trigger it. No luck. After half a day of searching, I am ready to give up my veteran search engine users badge. I have seen a few (very few) bus switches, but there should be a "poor mans" solution. I admit I am a noob at electronics, but this is just simple search engine stuff.

Is it harder that I thought or was I having a bad day?

[Qiaozhi]

I'll double check. Maybe I have something else wrong.


Unfortunately I am now obsessed with finding out what chip would be best for switching. It seems like the simplest thing you could possiby do in digital electronics. The fact that I can't find anything out about it makes me feel small and inadequate. Is it so simple that no one needs to talk about it? Before I started, I assumed there was some 74-something chip that would be perfect, and a quick search would yield said chip. It would be a simple matter to grab a bunch of them and use one of the five volt lines to trigger it. No luck. After half a day of searching, I am ready to give up my veteran search engine users badge. I have seen a few (very few) bus switches, but there should be a "poor mans" solution. I admit I am a noob at electronics, but this is just simple search engine stuff.

Is it harder that I thought or was I having a bad day?

Would it not just be easier to wire up a switch to effectively reconfigure the jumpers on the two drives. Mind you I'm not sure what would happen if you flicked the switch while the system was on, but it probably wouldn't be a good thing to do. Anyway, switching the 40-pin IDE cable will also have the same problem and it's harder to implement.
It would probably be best to put the switch on the back of the unit where no-one can mess with it.

[rube the noob]

Qiaozhi,

I was reluctant to do it that way because I wanted both drives to be completely independant. It would have the benefit functioning as two separate computers. So I could let the kids play on one, and download all the junk they wanted, and viruses and spyware would be isolated. I could run business and household stuff on the other one. Plus I had a storage drive I wanted to make available to both as a slave, which wouldn't work since I have a DVD and CD burner that I want to keep hooked up, and that would be five devices.

BUT, the pragmatic side of me wanted to get the project going, so I did what you suggested, and it works great. I undid all the power stuff and hooked up the jumpers to the switch. The position of the switch determines which drive is the boot drive.

An a side note, I had an old maxtor pci card that came with a hard drive. I didn't know what it did until I started working on this project. (it was going to be the source of my ide cable sockets, lol) So I have my extra drive working, and I can also see the other drives as a slave, which has benefits. Maybe I will just install linux on one and keep the other as windows.

For a switch, I am using a 115/230 voltage switch from some expired piece of electronic equipment. It is flat, doesn't stick out, and you have to be trying to get it to flip. Hopefully nothing bad will happen. (I have a three year old daughter)

It might be my imagination, but I think the pci card affects performance of the system, so I am going to get a USB enclosure for it, and pull the card. Then I can bring it to the coffee shop with my notebook computer and have all my junk.

Thanks for the help!!

[Seeker]

Hi Rube,
I do experimen for your wish to switch two HDDs. HDD mast be the same volume and type(this is nessary for record in BIOS).Two HDD are in master mode on same IDE 0 , I switch only HDD's ( +5 and +12, ground mast be connected) power when PC is OFF. I run WIN98 and LINUX separately and it is work.

[Seeker]

If you want connect 5 devices, you mast input some other 40pin connector. It is easy , there no matter where on cable you will clip it.
So, the configuration will be:
IDE 0 : HDD - master ; HDD-master ;DVD - slave
IDE 1: CD-master ; Storage dev. - slave

The HDD's power switch mast be some where in secret place , to avoid undesired switching over

[Qiaozhi]

Qiaozhi,

I was reluctant to do it that way because I wanted both drives to be completely independant. It would have the benefit functioning as two separate computers. So I could let the kids play on one, and download all the junk they wanted, and viruses and spyware would be isolated. I could run business and household stuff on the other one. Plus I had a storage drive I wanted to make available to both as a slave, which wouldn't work since I have a DVD and CD burner that I want to keep hooked up, and that would be five devices.

BUT, the pragmatic side of me wanted to get the project going, so I did what you suggested, and it works great. I undid all the power stuff and hooked up the jumpers to the switch. The position of the switch determines which drive is the boot drive.

An a side note, I had an old maxtor pci card that came with a hard drive. I didn't know what it did until I started working on this project. (it was going to be the source of my ide cable sockets, lol) So I have my extra drive working, and I can also see the other drives as a slave, which has benefits. Maybe I will just install linux on one and keep the other as windows.

For a switch, I am using a 115/230 voltage switch from some expired piece of electronic equipment. It is flat, doesn't stick out, and you have to be trying to get it to flip. Hopefully nothing bad will happen. (I have a three year old daughter)

It might be my imagination, but I think the pci card affects performance of the system, so I am going to get a USB enclosure for it, and pull the card. Then I can bring it to the coffee shop with my notebook computer and have all my junk.

Thanks for the help!!

Glad to be of assistance.
Although I would be concerned about having a shared disk drive between two systems when one of them has no virus protection. :confused:
You could also make your system dual-boot if you want to run either Linux or Windows. A better solution (and one that I use) is VMware. Then you can run Windows and Linux simultaneously, and even transfer information between the two operating systems.
http://www.vmware.com/products/player/

[rube the noob]

Thanks for the info, Seeker. I do have two of the same 160GB Maxtor drives, so I can try it with those. I first tried it with a 200GB and a 160GB, so that may have been my problem. Now I have talked myself into wanting the ability to share data between the drives, so I might see how I like the current setup.

Qiaozhi, VMware is an interesting option. Do you find the overhead costs you much in system performance? Does the free version do the job or do you need the full version?

Thanks!!

[diggerbarns]

switching hard drives

I have about 15 hard disk drives. A couple of nice big ones and the rest about 12-25 gig. These small ones are often thrown away these days. I buy caddies from ebay for about £5.00 each. This way I can put in a different disk depending on what I want to do. Kids have their own disk for games etc. I have one special disk for emails Ebay and stuff like this. Then I have other disks for important stuff that takes a lot of time. I have a couple just full with mp3's. Its surprising how much stuff you can get on a 12 gig disk. Keeping the internet disk separate from the others keeps my work safe from virus attacks.

[Qiaozhi]

Thanks for the info, Seeker. I do have two of the same 160GB Maxtor drives, so I can try it with those. I first tried it with a 200GB and a 160GB, so that may have been my problem. Now I have talked myself into wanting the ability to share data between the drives, so I might see how I like the current setup.

Qiaozhi, VMware is an interesting option. Do you find the overhead costs you much in system performance? Does the free version do the job or do you need the full version?

Thanks!!

Obviously there is some hit in performance, but not much. It's the guest OS that's running in virtual hardware, and the graphics gets slowed down a bit.
I actually have the full version, but I've tried the free player and there's no difference in performance. The only restriction is that you have no means of creating your own virtual machine, and must rely on the pre-configured versions that can be downloaded from the VMware site. The other problem is that you need twice as much memory. For example, if your system has 1GB of memory and you have a Windows host with a Linux guest, the memory gets split between the two. You're able to assign how much gets allocated to each, and in my case I assigned 500MB to each OS.