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Boot from B: or switch A and B

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vladstamate

Experienced Member
Joined
Dec 2, 2012
Messages
197
Location
Orlando, FL, USA
Hi all,

I am trying to make my 386 PC boot and here is the problem I am hitting. It has 2 floppy drives, a 5.25" and a 3.5". It seems to be setup that A is the 5.25" and B: is the 3.5". There is no autodetect in the BIOS (which is AMI btw) so I have to set it manually in there. I do not have a 5.25" bootable disk (no any way to make one) but I can make (and have) 3.5" ones. However the BIOS keeps trying to boot from the 5.25". Here is what I have done

1) Both drives connected and both set up in BIOS: it keeps trying to boot from A: (which is the 5.25") and complains (rightfully) that I do not have a boot disk.
2) Disconnect the 5.25" one (physically disconnect the data cable from it) but leave both set up in BIOS - it does not use the 3.5" and immediately complains that it cannot boot from A (it does not spin the 5.25", as there is no data cable to control it)
3) Disconnect the 5.25" one (physically disconnect the data cable from it) and have only the 3.5" set up in BIOS as B - it does not use the 3.5" and immediately complains that it cannot boot from A (it does not spin the 5.25", as there is no data cable to control it)
3) Disconnect the 5.25" one (physically disconnect the data cable from it) and have only the 3.5" set up in BIOS as A - it does not use the 3.5" and immediately complains that it cannot boot from A (it does not spin the 5.25", as there is no data cable to control it)

In other words, I do not seem to be able to convince the BIOS that the 3.5" is A: and to try to boot from it. I looked at the disk controller card but there is nothing obvious I can do. There are some jumpers though. Note that both drives use same cable so maybe the cable is at fault here (in the sense that it forces certain drive orders).

Any ideas of how I can make the PC boot from the smaller drive?

Regards,
Vlad.
 
I wouldn't say that the cable is "at fault" ;-)

Drive order is determined by the location on the cable (assuming that the cable has a section where a part of it is twisted): the drive at the end (after the twist) is drive A and the one closer to the motherboard (before the twist) is drive B. Hopefully your cable has compatible connectors.

Some BIOSes have an option to swap the drive letters (usually under BIOS features).

Floppy disk drives are not and can't be autodetected and have to be manually specified (unless the default is correct).

Good luck!
 
MikeS said:
I wouldn't say that the cable is "at fault" ;-)

Drive order is determined by the location on the cable (assuming that the cable has a section where a part of it is twisted): the drive at the end (after the twist) is drive A and the one closer to the motherboard (before the twist) is drive B. Hopefully your cable has compatible connectors.

Some BIOSes have an option to swap the drive letters (usually under BIOS features).

Floppy disk drives are not and can't be autodetected and have to be manually specified (unless the default is correct).

Good luck!
Click to expand...

Yup, you are right. I literally just found this out. The cable has 2x connectors for both big and small drives (for a total of 4 connectors). Connecting the small driver at the end of the cable made it "drive A:".

Now a matter of finding a way to create a DOS boot disk (I thought I had created one but the PC still does not like it). But at least when I press a key to re-try the drive spins properly and tries to boot from the disk, which means the HW is (hopefully) all ok.
 
You might need to provide pictures of your system and cable for better suggestions.

Does your cable have 5 connectors or does the end of the cable only have a card edge connector? You would need either a cable with the proper connector or track down an adapter to switch order of drives.

Another problem with some systems is that mounting the 3.5" drive in its normal position, the 3.5" drive will have to be the B drive because the cable can't be bent into position the other way. If you have a larger tower, you could move the 3.5" drive into a 5.25" bay (use an adapter), move the 5.25" drive to another bay so it can be reached by the middle of the floppy cable, and cover the now unused 3.5" bay.
 
You can switch the drives around just long enough to make a 5.25 boot disk. If your cable won't reach, unscrew the drive(s) for just this operation. If your cable is of the type which only has one of each type of connector and can't do that, then I'd recommend getting one that you can utilize here. They're dirt cheap, and in any case it's a good idea to keep a cable around with 2 of each connector type on it.
 
First, thank you all for the help.

MikeS said:
Exactly how did you go about making a boot disk? And which version of DOS?
Click to expand...

Argh...all bootdisks I tried did not work. Both 3.5" and 5.25".

For 3.5" I created them using a USB floppy drive and I found images here. I wrote them with rawwritewin-0.7 from .img files. I tried to boot one of them on my main PC using the same boot drive and it sort of worked. As in I got the "Starting DOS..." but then eventually it locked up. Now that could be because I am trying to boot DOS 6.22 on a very modern PC. Or maybe because the disk is not good.

If anyone has a pointer to where I can find images for DOS boot disk, I welcome those. I tried some other I found on the internet and no luck, the 386 keeps saying "DISK DRIVE NOT READY, Insert Boot disk in Drive A:"

For 5.25" I have the original Dos 3.3 disks from IBM. Those did not work either, but that could be related to age of the disk.

I also had problems in general reading back disks created with the rawwrite software and the USB floppy. Maybe there is something wrong with the USB floppy (and/or the disks themselves, although they are supposed to be new).

At this point, I am _kinda_ inclined to think that the 386 is probably ok, but somehow I am not creating the boot floppies correctly. Like I said, if anyone has a trustworthy link, that has been working before for disk images, I am all ears (and eyes). Also, for Windows (I have a Mac too, but no Linux machine) if there is a better software to write disk images, I am interested in that too.

Regards,
Vlad.
 
Well, you should certainly be able to read disks on the USB drive that you wrote on the same USB drive... Are the diskettes Double Density or High Density?
 
vladstamate said:
First, thank you all for the help.



Argh...all bootdisks I tried did not work. Both 3.5" and 5.25".

For 3.5" I created them using a USB floppy drive and I found images here. I wrote them with rawwritewin-0.7 from .img files. I tried to boot one of them on my main PC using the same boot drive and it sort of worked. As in I got the "Starting DOS..." but then eventually it locked up. Now that could be because I am trying to boot DOS 6.22 on a very modern PC. Or maybe because the disk is not good.

If anyone has a pointer to where I can find images for DOS boot disk, I welcome those. I tried some other I found on the internet and no luck, the 386 keeps saying "DISK DRIVE NOT READY, Insert Boot disk in Drive A:"

For 5.25" I have the original Dos 3.3 disks from IBM. Those did not work either, but that could be related to age of the disk.

I also had problems in general reading back disks created with the rawwrite software and the USB floppy. Maybe there is something wrong with the USB floppy (and/or the disks themselves, although they are supposed to be new).

At this point, I am _kinda_ inclined to think that the 386 is probably ok, but somehow I am not creating the boot floppies correctly. Like I said, if anyone has a trustworthy link, that has been working before for disk images, I am all ears (and eyes). Also, for Windows (I have a Mac too, but no Linux machine) if there is a better software to write disk images, I am interested in that too.

Regards,
Vlad.
Click to expand...
I use the self writing images here: http://bootdisk.com/bootdisk.htm
It seem to work fine with my USB drive. Perhaps you have a bad drive.
 
smeezekitty said:
I use the self writing images here: http://bootdisk.com/bootdisk.htm
It seem to work fine with my USB drive. Perhaps you have a bad drive.
Click to expand...

You know, it might just be. I tried using some of those self writing executables and I get (after reaching certain %):

Disk errror on track 46, head 1
Sector not found

I'll see about finding another USB floppy drive.

Regards,
Vlad.
 
vladstamate said:
You know, it might just be. I tried using some of those self writing executables and I get (after reaching certain %):
Disk errror on track 46, head 1
Sector not found
I'll see about finding another USB floppy drive.
Click to expand...

Disk error could indicare a bad disk. That's common. Try another one. It is also possible that the image is not good.
 
I'm with Ole. Bad disks are the most common problem. You need to format the disk first and verify that there are no bad sectors. It is *not* possible to write an image to a disk that is not perfect. Now, if you had a machine with a version of DOS running you could SYS a flawed disk that has been previously formatted and make it bootable since DOS knows how to ignore sectors already marked bad in the format. To recreate a disk from an image, however, it a totally different story.
 
Once you get your drive situation sorted out, there is a neat little utility called bootB which is a sort of passthru boot disk which will redirect a boot process to the B: drive.
I found a copy of it here:
http://www.coleskingdom.com/files/BOOTB.ZIP

Install the above onto a dedicated floppy that fits in your A: drive. then, whenever you want to boot to your B: drive, just insert that disk and boot your machine. You'll see the A: drive light up for just a second or two and then transfer to the B: drive and continue booting, assuming the disk in B: is bootable. It's a neat trick and quite handy.
 
Keep in mind it is easy to make a boot disk if you get the system booted. I faced the same issue with the drives in the wrong order and no other 5.25 drive to make one.
format /S X: will make a boot disk. X is the drive A or B
 
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