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Adding CD-ROM garbles HDD letters

Posted on 1998-08-19
Last Modified: 2013-12-16
Please help.
Situation: Asus VX97 board with dual PCI IDE controller. The system did work with the following drive/OS configuration: 812 Mb drive as primary-master formatted as FAT16. 244 Mb drive as primary-slave formatted NTFS.  212 Mb drive as Secondary-master formatted Fat16.  Pioneer CD-Rom as secondary-slave.  NT installed on primary-master, 95 installed on secondary master.  Dual boot from primary-master.  In this configuration everything works fine.  Booting to DOS 5 from floppy is also OK. All OS's see drive's correctly (using fdisk in DOS/95, DiskManager in NT)

And then, after months of deleting and reloading games because of a lack of disk-space, I broke down and acquired a 4.1 Gb drive and reconfigured the system as follows:
Primary-master  : 812Mb
Primary-slave   : 244Mb
Secondary-Master: 4.1Gb
Secondary-Salve : CD-ROM
I then reinstalled the operating systems, just to clean out the junk and this is where problems occur.  I figured why not install DOS to a hard drive and triple-boot? Not a problem. So, booting to dos 5 from floppy the drives show up fine in fdisk and I partion/format drive C: as FAT16.  After installing DOS 5 to C: and booting from HD, fdisk reports my disk config as follows:
1  C:   812Mb
2       244Mb
3       4110Mb
4  D:   812Mb
This is obviously erroneous.  Drive D:, in DOS, is a mirror of drive C:. Needeless to say, installing 95 to drive D: at this point actually installs it to drive C:. Note that partitioning/formatting the 244Mb and/or 4.3Gb drives in any way shape or form does not help or change things at all, even if the 4.1gig drive is partioned into 2 or more small logical drives. The only way the system sees the drives correcly is:
  1) boot DOS 5 from floppy. (why should this be different from booting from HD?)
  2) run windows NT (NT rocks)
  3) UNPLUG either the CD-ROM, or the 4.3gig drive. This clears up everything, but leaves one without the other :(
I would like to use the CD-ROM on the PCI IDE controller (with the 4 Gig drive at the same time,) but it's looking impossible.  It is an ATAPI CD-Rom.  All the drive jumpers and BIOS LBA/Normal modes are set correctly (CD-ROM is NOT entered in BIOS) I'm stumped (or would one say ignorant?)

Any help GREATLY appreciated.

Question by:redman082297
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Accepted Solution

ewilson earned 100 total points
ID: 1757826
don't put your new drive on the same IDE channel as the CD rom drive.. the ultra DMA on the newer drive does not work well with CD Rom drives... put one of your older drives on the same IDE channel as Your CD and you should be fine

Expert Comment

ID: 1757827
Also i have a question... why do you want to put the slowest device of your 4 drives on the same channel as your fastest... this will hinder performance.

Expert Comment

ID: 1757828
If you have UDMA in use on that drive, it's performance won't be hindered.
But, there is something wrong here......
Full capacity of your C: drive cannot be accessed with the Dos 5 FDISK command.(FAT16 limited to 2GB)
The only way to partition it as one drive using the full drive capacity is to use a FAT32 operating system.(Win95B or later)
How was the new drive formatted?

Author Comment

ID: 1757829
The reason I did this really is for no reason at all.  While trying to get the !@#$ system working, I was pulling disks left and right, trying to see if any one combination made a difference, but it didn't.  This is just the way they happened to be when I got sick of changnig them around.  But none-the-less, that doesn't seem to be the problem. I realized that while installing DOS, I had the CMOS set to boot from drives in this order: A, CDROM, C.  Evidently, this was was tricking DOS into thinking I had four hard drives, and it probably didn't know how to deal with the fourth.  After changing boot sequence to A, C, everything worked!
But, there was still a problem with windows 95.  After installing 95, I noticed that the hard drive LED stayed on, forever.  I tried switching all of the drives to use DMA (probably not a good idea on the small drive) and it seems to have cleared things up, but I'm still paranoid as I don't understand why this would make a difference.

As far as formatting with DOS 5 FDISK, I don't know why it worked.  The drive is only 812Mb.  I am still confused about the ultimate limitation on hard drives.  Having 16 bits with which to map a cluster forces dos to only see as far as 2 Mb, or is it approx. 500 Mb?  If it's 2Gb, doesn't Large Block Addressing take care of hardware limitations?  Although, I may have previously installed NT and used it's setup program to format the drive, but it's still FAT16! (after installing OS's over and over I can't remember any-more which way I did it, but I'm quite sure I used FDISK)

Thanks for the help!

Expert Comment

ID: 1757830
If you can see a 4GB drive listed in FDISK, rest assured you're running a late version of the program which recognizes FAT32 partitions.
FAT16 can access approx. up to 2GB with LBA enabled, and only 500MB without it.

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