I have an old PC with a HDD that was using Double Space. Since I do not need the extra space, and want to minimise the system use of RAM, I attempted to re-format the drive normally.

After typing fdisk c:, which (IIRC) did not produce any errors, the drive is now responding "Invalid media type" to any attempt to use it. I have tried format c:, fdisk /mbr, just fdisk, with identical results, "Invalid media type reading drive C". It is MS-DOS 5.0.

Any simple solutions? Which Norton tool should I use?

According to the BIOS diagnostics the drive is ok.

Clarification: I have never booted from this drive, always from flash cards in A: or C: (with no HD installed). All the slots A-D are PCMCIA. It is a HP Omnibook.

More clarification: the reason I mentioned DS is that I first tried to just format the drive, but it said I needed to use a DS-command (cannot remember the name), so I tried fdisk instead, which seemed to work, but after that it has been "invalid media type" at any mention of C:.

Also, there is only 4MB of RAM, so Norton Disk Doctor and some other Norton tools I tried do not run.

Addition: please note that this problem is solved. Thanks to all who replied.

  • Do you still have a D: drive? (Double Space remaps the real drive as D: or some other letter; C: represents the compressed contents. I can’t remember off-hand how FDISK deals with this.) Commented Dec 6, 2017 at 11:40
  • Well, yes, but it's read-only. I don't think Double space used more than one drive letter. (I have manuals that I could read, but will have a look at fips first).
    – Tomas By
    Commented Dec 6, 2017 at 11:57
  • The host drive is visible with DoubleSpace, usually as H: though (not D:, sorry). Are you sure it’s DoubleSpace on DOS 5? It was released with DOS 6 IIRC. Commented Dec 6, 2017 at 12:26
  • I checked the manual. It is MS DoubleSpace, and DOS 5 (HP Omnibook). And yes, there was a E: drive also. The manual says fdisk should work, so I am not sure what I did wrong.
    – Tomas By
    Commented Dec 6, 2017 at 13:51
  • 2
    Remember to reboot after running FDISK. It's not unusual for things to work improperly until you do a reboot, to force DOS to re-read / re-load certain tables in memory.
    – Ken Gober
    Commented Dec 6, 2017 at 21:17

3 Answers 3


to solve your memory problem take a look at this SO/SE QA:

My bet is you did not use highmem.sys or you are not loading lh what you can eating up Your base memory.

now There are few reasons for wrong media type I can think of...

  1. BOOT sector protection

    some BIOSes have protection of boot sector (from viruses) messing up formating and partitioning. In the case a warning message Y/N should appear but I saw few times it did not happen or even if pressed Y the format was corrupted. So check BIOS and temporarily disable this feature if you Enabled.

  2. Your system is infected by Virus

    There where some nasty boot sect viruses back in the days which may interfere with the formating/partitioning process causeing your problem. make sure you boot from virus free floppy/stick and do not run/scan files from HDD or stuff.

    IIRC There where also some Viruses that hides in the BIOS or loads from LAN on boot so just in case unplug LAN cables.

    Also Do not trust anything without proper scan. I got some infected pressed CD's from motherboards directly from manufactors. At that time the viruses where not recognized yet but after decade+ I got surprised when searching for old drivers ... :)

  3. Incompatible fdisk or format utility

    What OS you have (MS-DOS 6.22)? What FS (FAT16)? If yo mix MS-DOS 7+ utilities with older MS-DOS then you can run into similar problems. Make sure you got FAT16 and do not crossing any barriers (In such case use EZ-drive I think).

    IIRC FAT32 was only for the newer MS-DOS versions which where not a really MS-DOS like the old ones and not all programs runs in it properly.

  4. physical drive error

    BIOS drive test is unreliable for "newer" IDE discs. That was usable for the old MFM and on new IDE it was not doing anything reasonable. Do not use HDD format utility from BIOS as IIRC some IDE HDD could be permanently damaged by it

    To diagnose and remedy your drive try PQ magick I Think PQ 8.0 and earlier where meant for MS-DOS.

    Also each IDE manufactor at that time had its own HDD format utility to make a low level HDD format You can try that as a last resort.... They usually work like FDD image you format an floppy with it and boot from it ... They sometimes helped in case of no real physical damage is present but just magnetical one.

  • Thanks. Will see if I can use loadhigh for anything.
    – Tomas By
    Commented Dec 8, 2017 at 9:59
  • I actually managed to get it to work using fdisk and format. I do not know what fixed it (or what went wrong at first).
    – Tomas By
    Commented Dec 8, 2017 at 10:03
  • @TomasBy then all is well between Ground and antenna again ... When was the last time you unplug and plug the cables and Cards ...? Oxidation is a bitch (sorry for the expression but it is how I feel about it)...
    – Spektre
    Commented Dec 8, 2017 at 10:05
  • Well, it's a portable, so cables and cards have been in and out recently.
    – Tomas By
    Commented Dec 8, 2017 at 10:09

Is it an OmniBook 300 or 425? Then you are in luck, because I've done precisely that with my 300. This is an official support document from HP explaining how to configure a 425 (or 300) without disk compression, and remove both the DoubleSpace and MS Flash Filesystem drivers from RAM. I forget how much conventional memory you end up with, but it's well over 500 KB.


  ISSUE:HP OmniBook 425 - running MS Windows while freeing up a
              maximum of 590 KB of DOS memory.

  SOLUTION:To free up the DOS memory, two device drivers have to
              be disabled, DoubleSpace and the Flash File System.
              Disabling DoubleSpace will reduce the capacity of the
              hard drive to 40 MB and disabling the Flash File System
              will disable your access to drive D and the HP OmniBook
              425 Communication ROM card.  If access to either of
              these is necessary after following this procedure, see
              "Reinstalling the Flash File System" below.  This
              process should only be used with the hard disk version
              of the HP OmniBook 425 because the Flash File System
              will be disabled.  The following process describes
              copying the required files to drive C and editing DOS
              and Windows startup files.


                    LOST.  ALL DATA SHOULD BE BACKED UP
                    BEFORE CONTINUING.

              1. Exit Windows.
              2. Type FDISK C:and press [Enter].
              3. Answer YES to the "Proceed with FDISK (Y/N)? [N]"
                 prompt and press [Enter].
              4. Press any key to the "Press any key when ready . . .
                 " prompt to reboot the HP OmniBook 425.
              5. Answer NO to the "Do you want to format drive C:and
                 copy required files to it (Y/N)? [Y]" prompt and
                 press [Enter].
              6. At the D:prompt, type FORMAT C:and press [Enter].
                 Answer YES to the
                 "Proceed with Format (Y/N)?" prompt and press
              7. When prompted for a volume label, type OMNIBOOK and
                 press [Enter].


              1. At the DOS prompt, type D:\OBSETUP /F and press
                 [Enter].  This will copy most of the required files
                 from drive D to drive C.  Reboot the HP OmniBook
              2. Once the HP OmniBook 425 has rebooted, start File
                 Manager and open one window for drive C and one
                 window for drive D.
              3. In the window that displays drive C, select the C:\
                 icon to make the root directory active.  If a
                 replace prompt is displayed when performing the
                 following steps, answer YES.
              4. Copy the OMNIBOOK directory on drive D to drive C.
              5. Copy the WINDOWS directory on drive D to drive C.
              6. Copy the WINWORD directory on drive D to drive C.
              7. Copy the files in the TSI directory on drive D to
                 the WINDOWS\SYSTEM subdirectory on drive C.
              8. Copy all of the files in the root of drive D to the
                 root of drive C.
              9. Change the window that displays drive D to display
                 drive C and select the OMNIBOOK directory.  Move
                 OBMGMEXE.EXE  to C:\WINDOWS directory.
              10.     Change one window to display the
                 C:\WINDOWS\SYSTEM directory and the other window to
                 display the C:\TSI directory.  Move LLRSTS.EXE in
                 the C:\WINDOWS\SYSTEM subdirectory to the C:\TSI
              11.     Change one window to display C:\OMNIBOOK and
                 the other to display C:.  Move OBCIC.EXE in the
                 OMNIBOOK directory to root of drive C.
              12.     Delete WIN.BAT in the root of drive C.
              13.     Copy C:\AUTOEXEC.DOS to C:\AUTOEXEC.BAT.
              14.     Exit File Manager.


              1. Use Microsoft (R) Word and edit C:\CONFIG.DOS.
              2. Type REM at the beginning of the line listed below.

                    DEVICE=C:\WINDOWS\EMM386.SYS NOEMS X=D000-DFFF

              3. Save the file as CONFIG.SYS and again as CONFIG.WIN.
              4. Edit C:\WINDOWS\CONTROL.INI. and use Edit-Replace to
                 replace all occurrences of D:with C:.  If a replace
                 prompt is displayed, when performing these steps,
                 answer "YES".
              5. Save the file.
              6. Edit C:\WINDOWS\SYSTEM.INI and replace all
                 occurrences of D:with C:.
              7. Save the file.
              8. Edit C:\WINDOWS\WIN.INI  and replace all occurrences
                 of D:with C:.
              9. Save the file and exit Microsoft Word.
              10.     Select the HP Financial Calculator icon in
                 Windows Main group.  Press Alt+Enter to display the
                 Program Item Properties and change the command line
                 to read "C:\HPCALC.EXE".
              11.     Select the LapLink RA On/Off icon in the
                 Windows Main group.  Press Alt+Enter to display the
                 Program Item Properties and change the command line
                 to read "C:\TSI\LLRSTS.EXE /S".
              12.     Exit Windows.


              1. At the DOS prompt, type OBBOOT 3.  This will reboot
                 the HP OmniBook 425 and disable DoubleSpace and the
                 Flash File System.
              2. To start Windows, type MSWIN and press [Enter].


              1. Start Windows by typing MSWIN and pressing [Enter].
              2. Start Notepad and type the following lines.

                    C:\LLREMOTE /U

              3. Save the file as C:\WIN.BAT.
              4. Modify AUTOEXEC.BAT and AUTOEXEC.WIN files to use
                 this batch file.


              1. Exit Windows.
              2. Type OBBOOT 2 and press [Enter] at the DOS prompt.
              3. To disable the Flash File System again, type OBBOOT
                 3 at the DOS prompt.

                  Copyright  Hewlett-Packard Co. 1996
       This information is subject to change without notice and
                 is provided "as is" with no warranty.
          Hewlett-Packard shall not be liable for any direct,
        indirect, special, incidental or consequential damages
             in connection with the use of this material.
  • It's a 300. I don't think the flash driver can be disabled. I have no device lines in config.sys, and it loads the flash driver and one for power monitoring. I get 450k available RAM.
    – Tomas By
    Commented Dec 8, 2017 at 22:16
  • Read through the instructions. If you copy the files from D: to C: as specified, you can use OBBOOT.COM to reconfigure the OmniBook to boot without either DoubleSpace or the Flash Filesystem driver. It's a customized ROM version of DOS which loads these drivers before it ever even touches your CONFIG.SYS, so disabling them requires setting NVRAM options with OBBOOT. You probably won't quite get 590 KB like the doc says, but you should be able to get close.
    – db2
    Commented Dec 9, 2017 at 0:54
  • Ok, will try this.
    – Tomas By
    Commented Dec 9, 2017 at 1:36

FIPS is another disk partitioning utility for MS-DOS.

Although FIPS is primarily intended for altering partitions on an existing, formatted HDD, it can create new partitions from scratch. In my experience it is well worth trying as an alternative method of getting recalcitrant hard drives working again.

If you don't have FIPS.EXE, it is available from several download locations. It is normally supplied with Linux distros, as it is used to set up the HDD partitions before installing Linux alongside an existing OS. If you have a Linux install CD/DVD lying around, you will have a copy.

You will of course need to boot MS-DOS from floppy and then run FIPS from a floppy.

The included instructions will take you through the steps necessary. An online guide can be found here.

Once you have your partition(s) back, then reboot MS-DOS from floppy and issue format c: as normal.

  • I get to screen #3 in fips, the boot sector screen. At the bottom it says "Invalid jump instruction in boot sector: F6 F6 F6". Then it aborts.
    – Tomas By
    Commented Dec 6, 2017 at 13:57
  • If, as the comments under the question suggest, C: is a logical drive hosted on E:, then you can't directly partition C:. You would have to partition E:. The implication of the comments is that you can't.
    – Chenmunka
    Commented Dec 6, 2017 at 14:30
  • Yes, I gave confusing information. There is no other drive at the moment, or when I tried fdisk. In fact I am starting to suspect the drive was not using Doublespace at all, since I copied the files on it and it was only 5MB or so (out of 40).
    – Tomas By
    Commented Dec 6, 2017 at 14:37

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