Instructables

Dual Operating System Computer with no OS menu!

Picture of Dual Operating System Computer with no OS menu!
Ok, do you want to run a dual OS computer without the hassle of boot menus? Than this is the computer mod is for you. Two hard drives, some wire, some switches, and you can simplify a dual OS (Operating System) computer to!

I'm using the master/slave pins on the back of the hard drive in conjunction with a couple DPDT switches to "set" the OS before starting the computer. So each hard drive can be set Master or Slave from the front of the computer BEFORE turning the computer on.

Be sure not to flip the switches while the computer is running... could be a bad thing :D
 
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Step 1: Mounting the switches

Picture of Mounting the switches
starting with a couple DPDT (Double Pull Double Through) switches. I mounted them on a unused 3.5 bay cover... but anywhere out of the way will work.

Step 2: Building the harness

Using a couple CD drive audio cables were going to manufacture a wiring harness for our switches. I used these cables because it would hold on to all 8 jumper pins in the back of the hard drive. You could use any type of wire connector that is designed to connect to jumper pins. The wire leads from the power and reset buttons in an old case would work well too.

I removed the "thick" wire from the audio cable because it was not shielded and moved the other wire over (finished product in the second photo). Very patient/delicate work, but worth it. By pressing in on the metal tab that holds the wire in place, the wire will slide out connector and all from the molded plastic. This allows you to change the wires position in the plug.

Using a utility knife I also shaved off the "clips" and alignment pins from the molded plastic connector. They won't fit over the jumper pins otherwise.
junits153 years ago
my dad did something like this way back in 2000, he had two hard drives both 44pin IDE with windows ME (lol mistake edition) one 3gb and on 40gb, the 3gb was for me and my brothers and the 40gb was for my parents. Except he used one huge switch and mounted it on a rear PCI cover. Preventing prying hands from switching it while it is running. The only disadvantage is that with a dualboot setup, the two drives can easily access the files on each other, not so with this. Nice job though.
Grimptan (author)  junits153 years ago
Actually If your wanting to have a dual os with 2 versions of Windoze and prevent a user that doesn't know much about computers. Just go into the hardware manager and disable the opposing hard drive in each OS. Easy to get arround but if it's rookies your dealing with it should sufice. Or if it's a more advanced user insetead of switching the master/slave jumper get a 4 pole switch and switch the power and set them both to master.
yes but by controlling the power to the drives nothing can access the other. :)
batman964 years ago
OK, so maybe I missed it, but can this set up be used with a SATA HDD and an older IDE drive?  If So, could you explain how to accomplish this? I just switched from XP to Windows 7 OS and I can no longer run my favorite RTS game, Cossacks by CDV (yes I know it's old but I still enjoy playing it). I have XP, along with my game on my old HDD and my Biostar M-board has connections for both. PS I LOVE your idea and I want to use it if it is possible for the HDD config I have! I like Windows 7, but... I don't like the fact that it dosen't support very many older video cards and drivers, nor some popular older games.  Hummn, I wonder if "Bill" even remembers MS "Age of Empires"?  Will it run on 7? Anybody know?
Ted sez...
Grimptan (author)  batman963 years ago
Sense posting this Instructable I've had the chance to mess with SATA a bit. I'm not sure it would work. You could try interupting the power but as i remember it I had to "point" the bios to which SATA drive had the Linux os and use the Grub boot loader to do a dual boot system. On the Windoz side of things I realy don't know how you would dual boot 2 Windows opperating systems with out a boot manager of some sort with SATA. All new motherbords still have the old tried and true IDE connector and this could still be done, but there will be a performance trade off. it would have to be 2 IDE drives or 2 SATA drives. However thinking about it... I had to point the bios to the linux hdd because I was sporting 3 hdds in the same system. So It would stand to reason that if you were to Interupt the power to a SATA drive on a 4 pople switch useing a 4pin to SATA power addapter... only one hdd would be on at any given time so there would be no confusion in the bios as to which hdd had the OS. just don't add an extra hdd to the system later or you'll regret it... As for the games and such if you find the .EXE and right click on it you can get to properties and the Windows compatability tab and tell the computer this program worked on win 98 or xp or etc... don't know if that will help, I haven't gotten far with it. but it must work for something :)
rkr4 years ago
I believe you mean 'double pole, double throw'.
RelaxedSoup4 years ago
Actually, you can read/write to your Linux drive/partition in Windows (although you do have to use 3rd party software). It's called "Ext2 Installable File System for Windows", I used it a while back to edit GRUB while I was in Vista.
what OS's are you running?
He said: Linux Left, Windows Right...
REA4 years ago
your comp looks like my dad's Pro Tools comp.
my pro tools pc is inside a desk draw its invisible lol.
UbuntuNinja5 years ago
You have one of those mini computers? Cool! What are the specs on it? I like the idea of taking the menu screen out of dual booting. Do you like the computer?
Grimptan (author)  UbuntuNinja5 years ago
Shuttle SN41G AMD 2500+ 1g DDR 400 ram BFG G-Force 4 7600 OC 512mb video Maxtor 80g ATA133 (Windows XP sp3) Samsung 40g ATA100 (Ubuntu Linux 8.10) Top of the line stuff... well it was... 5 or so years ago :P I have just seen no real reason to upgrade, she's still fast enough for whatever I throw at it... most power hungry game I throw at it is Oblivion maybe Counter Strike. The idea here was for old ATA drives. Designing the same computer "style" is still possible with newer components. The shuttle box is still around... only with newer guts, and if you use switches to interrupt the power to SATA drives you'll have the same effect as switching master/slave on ATA drives. (unnatural is dead right in his post) use the switch to turn off the drive with the unwanted OS and turn it back on if you want file access to that drive... gatta love that hot swap :P And yes I likes! considering the computers age i'm surprised it hasn't died on me yet. In 5 years I've replaced the power supply once, aside from that no problems.
gothicbob5 years ago
This is cool, quite an elegant solution. As an alternative for sata drives you could load grub onto a usb drive, so that it looks at the grub on the usb if it is there and boots OS1. When usb isn't there it loads grub from the harddrive which boots OS2. Nowhere near as elegant, but its a solution.
error325 years ago
I think this is a creative approach. However not the smartest thing to do, besides I don't see why you would not want to use a boot manager but thats just my $0.02
Grimptan (author)  error325 years ago
I was forever walking away from the computer after turning it on and ending up in the wrong OS. I just kept missing the grub menu and needed to restart the computer. Just a "lazy man's" fix.
crapflinger5 years ago
also....unless you're using the linux file system (EFS?) windows can detect the drive and use it....so if you're using your computer specifically for a dual disk-dual boot scenario where you want to access either OS's drives from the other OS.....then format your linux drive in NTFS when you're setting it up
PKM5 years ago
Great idea, except.. surely most people l33t enough to want to use dual boot will be using SATA drives these days? I've been using SATA hard drives since my first Shuttle in 2006 (before I started dual booting). If you can think of any other way to do this I will be your biggest fan forever, I hate that moment when you realise you weren't concentrating on the boot menu so are loading into the wrong OS and have to restart.

I tried with a boot floppy once that just had a copy of GRUB with the opposite boot order to the copy on the hard drive, so disk in = Windows, disk out = Linux, but couldn't make it actually boot from the floppy.
Unnatural PKM5 years ago
Just a theory: maybe pointing the switches to the power lines, so you can choose what drive will be powered on? Assuming the motherboard is smart enough to boot from the right disk each time :D
If i remember correctly, i did see a computer mod, where the box was turned upside down for linux, and right way round for windows.. Goes to google it.
gmjhowe gmjhowe5 years ago
It was one of the mini itx mods.

Here

You might have seen it before.
PKM gmjhowe5 years ago
I have indeed seen that one, but I remembered it being a bit involved.

The final step was to take an assembly language MBR boot loader program and modify it to read the state of the tilt switch

Disassembling a boot loader and writing in a routine to poll hardware through the COM port (which I don't think I even have) in assembly language? Yecch. I may be crazy but I'm not that crazy- my love for assembly language stops at writing trivial demonstration programs on an ARM, thank you. The idea of hand coding CISC gives me the shivers. You're welcome to try it out if you want, here are the docos for 80x86 instruction set :)
crapflinger PKM5 years ago
you could modify the "power off to the SATA switch" idea...to work with the flip the pc over idea....just make the tilt switch turn the power on to one drive in one orientation and then the other drive in the other orientation
PKM Unnatural5 years ago
.. yep, I think I'm your biggest fan forever :) As far as I know the motherboard will check the SATA devices in order, so if one of the drives is powered off it should just skip that one. Problem- I traditionally dual boot from one multi-partition drive, with a partition per OS and a shared one for file storage, this approach might not work so well for that, but I think you may be onto something. I guess you could have a physical drive per OS and a shared third physical drive, if you wanted to go the whole hog, or given SATA can hot swap just power on the second drive once you've booted up. When I am done going on holiday and moving county I will probably rejig the OSes and try out your suggestion of switching the power supplies :)
Pasketti5 years ago
You should be able to do this with only one switch. Most drives have the jumper pins shorted for "master" and disconnected for "slave". So wire the switch so that one way shorts the master pins on one drive, and the other way shorts the master pins on the other drive.
yztay5 years ago
I like it
AndyGadget5 years ago
Nice idea. If I was doing this I think I'd use slide rather than toggle switches. They'd be harder to accidentally knock into the wrong position. I agree wholeheartedly with your comment about using different size drives. Even when you double-check the source and destination, it's always a pulse-quickening moment when you press 'enter' to format/image/overwrite a drive when it's the same size as the boot drive.
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