[Ham-Computers] RE: Need help with DOS

[Hsu, Aaron]

Brian,

Looks like you're not the only one who's rusty with DOS as the replies so
far have overlooked one thing (or is too new with computers to know)...DOS
has no "native" support for CD-ROM drives.

The BIOS will typicaly initialize/enumerate any IDE/ATA device attached, but
it's up to the operating system to provide I/O and file structure support.
Many BIOS' will support booting from a CD-ROM, but that support is
relatively new (added during the past few years).

For DOS to use a CD-ROM drive, two things are required.  The first is a
device driver for the CD-ROM drive.  This driver is the API that allows DOS
to communicate with the CD-ROM drive.  Luckily, most IDE CD-ROM drivers for
DOS are based on the "Oak Technology" reference driver and this driver
supports most any CD-ROM drive.  The "newest" driver I have is dated 1997
and it works fine with all the current CD-ROM drives I've tried.  It will
also recognize most DVD-ROM drives as CD-ROM drives.

The second thing required is file structure support.  Hard disks and
floppies in DOS use the FAT12/FAT16/FAT32 file structure.  This structure
defines a sector as having 512 bytes of data and DOS will only recognize
media with 512 byte sectors.  DOS/Windows CD-ROM's typically use the
ISO-9660 or "High-Sierra" file structure which define sectors as having 2048
or 2352(?) bytes of data.  So DOS needs a "translator" (aka "extension") to
recognize other file formats.  For CD-ROM support, Microsoft released the
"Microsoft CD-ROM Extensions" (MSCDEX.EXE).  I believe this was first added
to MS-DOS 5.0.  This basically allows DOS to recognize the CD-ROM file
structure.

Putting these two together, the device driver goes in the CONFIG.SYS file.
MSCDEX.EXE goes in the AUTOEXEC.BAT file.  Both of these are executed during
boot and add support for CD-ROM discs.  When MSCDEX.EXE loads, it will tell
you what drive letter was assigned to the CD-ROM drive; or, you can also
manually specify a drive letter.  Here are sample lines for each: (I'm using
Compaq's CD-ROM device driver, though again, they're all basically based on
Oak's driver)

CONFIG.SYS
device=CPQIDECD.SYS /d:CD001


AUTOEXEC.BAT
MSCDEX /d:CD001 

For these two examples, the "CD001" specifies a device "name" I gave the
drive - you can use any name up to 8 characters long.  The "/d:" is the only
requirement for both and they need to match.  There are additional
parameters (including one to choose a specific drive letter to assign), but
this will get you started.

Please feel free to contact me if anyone has any questions!

  - Aaron Hsu, NN6O (ex-KD6DAE)
    {nn6o}@arrl.net
    {athsu}@unistudios.com
    No-QRO Int'l #1,000,006
    . -..- - .-. .-   ".... . .- ...- -.--"
 

p.s.  Xtree Gold???  Man, I haven't seen that app in ages!



-----Original Message-----
From: Brian K. Gaskamp [mailto:bkgaskamp@juno.com]
Sent: Monday, March 29, 2004 7:18 AM
To: ham-computers@mailman.qth.net
Subject: [Ham-Computers] Need help with DOS


Hi gang I have computer in my hands that does not have Windows and I'm
trying to install Xtree Gold via the cd-rom and can't figure out which drive
is the cd-rom.

My days of messing with DOS are rusty.

I downloaded Xtree Gold and put it on CD and want to load it on the older
computer to see what it has on there.

Can anybody help, I'm sort of lost.

73,
Brian

KA5BKG



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