RAM drive drive letter allocation

Posted on 1997-06-01
Last Modified: 2013-12-16
I have created a RAM Drive but cannot access it, since the drive letter it gives conflicts with the CD drive letter.  I consequently changed the CD drive letter, but the RAM drive still won't start-up (in fact Windows recognises a conflict during start-up, and refuses to boot).

Is it possible for ME to choose the RAM drive letter?
Assuming it isn't, how can I make it work for me?
Question by:Martinr
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Expert Comment

ID: 1748526
Couple of questions:

I'm assuming you're using RAMDRIVE.SYS to set up the RAM Drive.  If you are, I believe the answer is no, you cannot pick the drive letter.

Are you loading DOS (or 'Real Mode') CD-ROM drivers?  If you are, check to see if you have enough driver letters free (with good old LASTDRIVE=x in your CONFIG.SYS, where x is a letter from F-Z that is a few letters above your existing partitions) and assign your CD a higher letter by adding /L:x  (again, something F or higher) to your MSCDEX line.  Or REM out the CD drivers and let Win95 load it for you.

What error message do you get from Win95 when it comes up with the wrong configuration?

Depending on what you are using the RAM Drive for, you may find that VRAMDir will work better for you.  It is  Win95 native, does not require a drive letter (it does take a subdirectory), and dynamically resizes based on what you put in it.  Check it out at

Hope this helps!
LVL 14

Expert Comment

ID: 1748527
Yes, you can name your drive letter. make sure you have setup ram
drive this way.

To create a RAM drive using
Windows 95, perform the following steps:

1.Restart your computer. When you see the "Starting Windows 95"
message, press the F8 key, and then choose Command Prompt Only
from the Startup menu.

2.Use any text editor, such as, to add the following line to the
Config.sys file

device=<path>\ramdrive.sys <x> /E

where <path> specifies the location for Ramdrive.sys and <x> is equal
to the total amount of RAM (converted from megabytes to kilobytes)
minus 4096 (4 megabytes are required for Windows 95 to start). For
example, if you installed Windows 95 on drive C in a folder called
Windows and your computer has 16 megabytes (MB) of RAM, add the
following line:

device=c:\windows\ramdrive.sys 12288 /E

The value 12288 is derived from the following formula using the
example above:

(16 * 1024) - 4096 = 12288 bytes

NOTE: The Ramdrive.sys line must follow the Himem.sys line, or the
RAM drive may not function.

NOTE: Windows 95 is limited to a 16-MB RAM drive. For additional
information, please see the following article in the Microsoft Knowledge


TITLE : Err Msg: Not Enough Extended Memory Available to Start...

3.Save the Config.sys file and then restart your computer normally.


4.If the problems no longer occur, halve the value for <x> in the Config.sys file and restart your computer. Repeat these steps until the problem returns. Once it returns, the faulty RAM is in the area that you most recently removed from the RAM drive. Contact your hardware manufacturer about replacing this memory.

5.If the problems persist, there may be a problem in the memory above the high memory area (HMA) that Ramdrive.sys is not using. To test the memory above the HMA (starting at 1088K), remove Ramdrive.sys from the Config.sys file and add the following line to the Config.sys file

device=<path>\himem.sys /int15=<x>

where <path> specifies the location for Himem.sys and <x> is equal to the total amount
of RAM you want to exclude from Windows 95's use. For example, the line
"device=c:\windows\himem.sys /int15=4096" prevents Windows 95 from using the
section of memory from 1088K to 5184K (or roughly the first 4 MB of RAM above
conventional memory + the UMA + the HMA). If the problems no longer occur, this memory needs to be replaced.

If you continue to have problems, one of the following situations may exist:

The problems may be caused by memory within the 1088K of RAM that the RAMdrive and HIMEM statements cannot reserve for Windows 95. To test this, try new memory modules or switch the order of the RAM modules in your computer. If you are unfamiliar with this process, Microsoft recommends that you contact your hardware
manufacturer for assistance.
The problems may be caused by CPU cache RAM. Many new processors implement a
method of optimization that uses motherboard and internal CPU cache RAM to
increase performance and optimize data and code execution. This cache is used to
offset the number of direct reads that are performed against main memory for
frequently used data and code.

To test this, disable the internal and external CPU cache. For information on how to do this, please read your hardware documentation or contact your hardware manufacturer.

If this isn't to your satisfaction you may reject or get back with me for further investigation


Author Comment

ID: 1748528
That's all very fine & good, Smeebud.  I got that info. MS myself, but it doesn't tell you how to change the RAM drive letter, or how to avoid a conflict!   Sorry!

P.S.  That's why I made this question worth 200 points, because I can't find any documentation on the subject.  :-)
LVL 14

Expert Comment

ID: 1748529
How about trying changing your CD drive letter. It's perfectly legitimate and perhaps the conflict go away. If you want to try this:
1.Click the Start button, point to Settings, and then click Control
2.Double-click the System icon, then click the Device Manager
3.Select the CD-ROM you want to change from the list, then click
the Properties button.
4.Click the Settings tab.
5.In the Reserved Drive Letters section, set Start Drive Letter and
End Drive Letter to the drive letter you want the CD-ROM drive
to use. Click OK until you return to Control Panel.
6.Restart the computer.

The CD-ROM drive letter should now be the letter you selected.
I would then look in my registry for ?: for all drives to see that all are recognised
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Author Comment

ID: 1748530
Smeebud, please re-read the part of my original question that says "I consequently changed the CD letter...".        :-)

But thanks anyway!

Accepted Solution

val_m earned 200 total points
ID: 1748531
This might be out of the  blue, but have you tried to set your last drive letter in config.sys.  There is a command called lastdrive which says how many letters for drives your computer can use.  If it is not specified in config.sys then DOS/Windows assumes it to be E, so if you have two hard drives and CD ROM drive (C, D, E) all your letters are filled and there is no drive letters left for RAM drive.  Trying setting your last letter to Z and see if it works.  Example -here is how your line would look inside of config.sys

Here is an exception from DOS help file on LASTDRIVE


Specifies the maximum number of drives you can access. You can use this
command only in your CONFIG.SYS file.

The value you specify represents the last valid drive MS-DOS is to




    Specifies a drive letter in the range A through Z.

Author Comment

ID: 1748532
Thanks Val. M.  It was indeed the lastdrive specification.
It now works like a baby!

One point to note however, the max. size is 32Mb not 16Mb as specified.

P.S.  After all that, I decided to use VRAMdir anyway.  It is better!  So thanks to Parody for the suggestion.

Author Comment

ID: 1748533
Thanks Val. M.  It was indeed the lastdrive specification.
It now works like a baby!

One point to note however, the max. size is 32Mb not 16Mb as specified.

P.S.  After all that, I decided to use VRAMdir anyway.  It is better!  So thanks to Parody for the suggestion.

Expert Comment

ID: 1748534
Ah, well.  Should have answered. Don't forget to pay your $10. :)


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