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AnyDrive – Use bigger drives than your BIOS permits!

I've mentioned this use of this Dynamic Drive Overlay software before, but I just want to go over some of its intricacies. Although 90% of it is totally straight forward, there's a few gotchas that you need to be aware of:

  1. It only works when the MBR has been 'booted' first
    This means that, if you have AnyDrive installed and you want to boot a floppy which can see the drive in full, you need to attempt to boot the HDD first, holding shift, to then boot the floppy straight after.
  2. When installing, use the drive number, not letter
    I first installed it on drive C instead of drive 0, this caused all sorts of strange issues.


The best way to do this is to format your 3 DOS 6.22 installation disks and then copy the ANYDRIVE.EXE file over onto the first disk. Boot your machine into DOS and then hit F3 twice to exit out to the command prompt.

From here, run the ANYDRIVE command to get an idea as to your current scenario. You can use ANYDRIVE S to check an installation, if any exists. Note that if you booted straight off your floppy then ANYDRIVE will tell you that it's not correctly loaded. This is perfectly acceptable if you have booted from a floppy and not let the HDD initialise first.

To get an old 840mb HDD running on my 386, I did the following:

  1. Build 3 DOS 6.22 floppies
  2. Copy ANYDRIVE.EXE onto the first disk
  3. Install the HDD into the computer and then boot the first DOS disk
  4. Hit F3 twice to get out of DOS Setup
    (ANYDRIVE 0 1647 16 63 for my Quantum Trailblazer 840AT as C:)
  6. Remove DOS Disk 1 and Reboot
  7. Hold down LEFT SHIFT to tell ANYDRIVE that you want to boot from a floppy
  8. Wait for ANYDRIVE floppy prompt and then insert DOS Disk 1 once again
  9. Install DOS as per usual (it should format to the new size of your disk)

Usage and Boot-time quirks

Once it's installed, and your OS is installed, it's all happy days. Everything is fine until you try to boot from a floppy. As per every old BIOS, boot will be handed to the floppy drive prior to the HDD and therefore the HDD won't be initialised until later. If this happens, then ANYDRIVE wont be initialised correctly and your actual BIOS settings will be used.

This is a problem. As any attempt to then access C:, which has been partitioned and formatted based on ANYDRIVE settings, could cause all sorts of damage as the geometry will be wrong!

To prevent this, make sure your boot disks are ejected and hold shift when your machine starts... you'll instead see the ANYDRIVE boot line and then a prompt to boot from A:. Booting your boot floppy at this point will ensure that any software afterwards sees your ANYDRIVE settings rather than BIOS settings.

I hope this helps anyone trying to get more storage on their older dinosaurs!