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Can't boot dos from floppy - Weird!

N

Nama

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I have been restoring a 386, and have been experiencing a weird problem in that when an IDE device is attached (e.g. IDE drive, or CF card in a CF to IDE adaptor) I am unable to boot from a floppy drive. On boot-up the machine posts and the floppy drive is accessed and it seems to start to load, but then the machine just seems to hang (no onscreen prompts about FDD failure or anything).
I am however able to access the floppy drive after booting from the IDE device with no noticeable issues. If I remove power from the IDE device, only then can I then boot from the floppy.
I have tried deactivating the IDE device in the BIOS (but still keeping power connected to the IDE device), changing the boot order, changing floppy drives inits (both 3.5 and 5.25)... but the only thing that works is physically removing power from the IDE device, then I am able to boot via floppy.
Wondering if anyone has any ideas what could cause this?

Cheers
 
I would have thought maybe the boot order, but you mentioned that you tried that.
 
Yeah, I've switches A drive and C drive around. No change.
When trying to boot from the 5.25" drive (that is considerably noisier than the 3.5" drive) I can hear more of what the drive is doing. It seems like its booting for about 3 or 4 seconds, then always followed by 4 sharp and precise head moves, and then nothing. Not sure if that is a clue or anything, but thought it may be worth mentioning.
 
You could try deliberately formatting a non-bootable floppy and then rebooting with it in and see if you get the non-system disk error. If you do, then the problem isn't the BIOS getting the boot sector into memory and jumping to it, but something in the process of loading DOS from a bootable floppy, e.g. DOS probes attached HDDs and parses their partition tables and gets badly confused somehow.
 
Makefile said:
You could try deliberately formatting a non-bootable floppy and then rebooting with it in and see if you get the non-system disk error. If you do, then the problem isn't the BIOS getting the boot sector into memory and jumping to it, but something in the process of loading DOS from a bootable floppy, e.g. DOS probes attached HDDs and parses their partition tables and gets badly confused somehow.
Click to expand...
Good idea...Actually I can answer that question already as I did put a non boot floppy into the system. It shows the error saying that the disk is a non bootable.
What I will do this evening is try to format and make a bootable floppy on this actual 386 system. All the boot disk I've been using have been made on my 486...not sure what that will do, but anything is worth a shot at this point.
 
Chuck(G) said:
Here's a thought--since only the first sector is read to get the message, are you certain that the drive type set in the CMOS setup matches what you have installed?
Click to expand...
Thanks for the reply...Yes, pretty sure. I've tried it with two 3.5" 1.44M drives, and a 1.2M 5.25" drive...each time changing the BIOS. The BIOS in my 486 machine has the option to flip the order of the two floppies (physical drive A become drive B, and visa versa)...but the 386 BIOS does not have this option. I'll try a few option this evening and see if anything changes.
 
ok...so I have no real idea what happened, but suddenly it started working. I tried to format a floppy in the 386, and at first it didn't work...it just sat there, drive spinning, but doing nothing. So I power cycled and tried again and nothing, and finally tried one last time and suddenly it started to format. Then for some unknown reason it could boot off of both 3.5" and 5.25" DOS boot floppies, wether they were made on the 486, or on the 386...no idea what the problem was, but I'm glad it's working now...Something else that seems to 'fixed' itself at the same time is I can now attach a second IDE drive (drive D) and it is recognised. I was having trouble doing this before. but suddenly started working!!!!
I wonder if the two issues were related...quite possibly.
Thanks for all your support. Fingers crossed the problem doesn't return.
 
I'd imagine a bit of corrosion on connectors finaly got clean and made good contact.

Good to se it is functioning fine now:)
 
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Caluser2000 said:
I'd imagine a bit of corrosion on connectors finaly got clean and made good contact.

Good to se it is functioning fine now:)
Click to expand...
Quite possibly. This motherboard did have a battery leak and a slight bit of trace repair done, and the keyboard connector and P8 and P9 power connectors replaced...but everything was thoroughly check and cleaned...but you never know
 
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