# Why would a CD-ROM in an MS-DOS 6.22 system not allow file access?

I have an OS/2 Warp CD that I am wanting to use as the installation media on an IBM PC 350 Pentium system. I have already installed MS-DOS 6.22 and the IBMIDECD.SYS driver for the CD-ROM drive on the boot HD. When I boot the system, it seems to install the driver and MSCDEX.EXE is loaded and reports drive E: is available (the CD-ROM drive).

The exact driver loading information from my CONFIG.SYS is:

DEVICEHIGH=C:\IBMIDECD.SYS /D:IBMCD000

And the command in my AUTOEXEC.BAT is:

C:\DOS\MSCDEX.EXE /D:IBMCD000 /L:E

I can switch to E:, and I can use the DIR command to see the contents of my CD-ROM, but I cannot access any of the files on the CD-ROM. The transcript below shows this "weirdness".

ibminst      <DIR>         10-30-01   6:20p
info         <DIR>         10-30-01   6:20p
install  cmd           956 01-04-01   2:43p
options      <DIR>         10-30-01   6:23p
os2image     <DIR>         10-30-01   7:26p
readme   add               10-30-01   7:39a
readme   txt               10-30-01   7:39a
rspinst  exe       478,064 10-27-01  10:50p
sample   rsp        81,781 10-27-01  10:50p
technote txt       214,878 11-02-01  11:48a
vcu      exe       131,347 10-16-01   3:29p
vcu      msg         1,760 10-16-01   1:26p
22 file(s)      1,052,303 bytes
0 bytes free

E:\>cd info
Invalid directory

E:\>cd e:\info
Invalid directory

E:\>type readme.txt
File not found - README.TXT

E:\>


If I insert the same CD into my modern computer, I can see and access all of the contents. Under Mac OS X, the CD is recognized as being ISO 9660 format.

What problems with the CD, CD-ROM drive, and driver setup in MS-DOS 6.22 could possibly be causing this behavior?

• I wonder if DOS 6.22 cannot handle lowercase filenames.. Aug 14, 2017 at 22:18
• @traal MS-DOS is case insensitive, but case preserving. Aug 14, 2017 at 23:14
• @RobertColumbia MS-DOS isn't case preserving, it will convert everything to uppercase.
– user722
Aug 15, 2017 at 0:26
• The file system on the CDROM uses various extensions. It's possible that the MS-DOS driver doesn't understand the extensions, and the "base" data doesn't work as it should, while the data in the extensions is valid. Aug 15, 2017 at 4:35
• Also, you should be able to boot from one of the CDs directly, without using DOS or floppies. Aug 16, 2017 at 13:32

## 1 Answer

It appears that the CD-ROM doesn't have a valid ISO 9660 file system. ISO 9660 requires that the file names be entirely in uppercase, lower case characters in file names aren't allowed. The directory listing in your screenshot shows only file names with lowercase letters instead of only uppercase as you'd expect to see in a MS-DOS directory listing.

The error message File not found - README.TXT shows that MS-DOS is looking for a file named README.TXT despite the fact that you typed readme.txt. MS-DOS automatically converts file names to uppercase since not only does ISO 9660 require uppercase file names, so does MS-DOS's own FAT file system.

The OS/2 Warp 4 CD-ROM came with three floppy disks that were used for booting the installation, as the CD-ROM itself wasn't bootable. If you want to install OS/2 Warp 4 then you should probably track down those disks, as the installation may not work without them.

• +1 for your last para. OS/2 actually booted a mini-version of itself from the floppy disks and read the CDROM from there. The installation CD was never intended to be read from DOS. Aug 15, 2017 at 6:53
• No, the CD was intended to be read from DOS — that’s how you wrote the boot floppies if the originals stopped working (the CD has a copy of XDFCOPY along with the floppy images, usable from DOS and OS/2). IIRC the Warp 4 CD was bootable directly too, but perhaps that was just 4.5 (I’ll check later). Aug 15, 2017 at 11:15
• @StephenKitt Hm. That only implies that \DISKIMGS\OS2\... needs to be readable to fetch the disk images. Maybe the OP can try that? If I recall it right, one needed Disk0CD, Disk1 and Disk2 only (and, obviously, xfdcpy.exe to write the images to a physical floppy) Aug 15, 2017 at 12:24
• Maybe the ISO requires the Ross Ridge extensions? Aug 17, 2017 at 0:11
• Rock Ridge, that is. Aug 17, 2017 at 9:14