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'[OT] (Totally, completely). Hard drives over 3GB?'
1999\11\17@210403 by William Chops Westfield

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1. You can only have 2 GB under a FAT16 partition. You can partition the
   disk into volumes (using FDISK plus FORMAT) of 2 GB or less to get it
   working in DOS.

The other thing is that you can only have two dos/windows "partitions"
on a drive.  To get more than two logical disks, you carve up the 2nd
partition ("extended dos partition") into multiple logical drives.

Also, the partition table only has room for 4 partitions total, a minor
point (since DOS only uses two of them) that drove me crazy when I tried to
install linux...

(If you don't mind wasting space, you can probably set up your 15G drive
and only use half of it for dos/etc due to that 8G limitation...)

billw

1999\11\18@074413 by paulb

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Perhaps I had better clarify a few things I missed in my essentially
brief earlier posting.  I've had plenty of suggestions, but no-one
actually pointing me to an actual *specification*.  Thing is, I rather
fancied I'd seen one somewhere on the Web.  I wonder if it was on
Wotzit?

 Anyway, my question refers to W95 OSR2, FAT32 and two partitions, the
extended partition including *seven* logical drives, the primary and two
of the "logical" drives being 2 GB and the others 1 GB.  Yes, that
totals 11 GB, the other 4 GB and two partition slots are reserved for
Linux as an option.

William Chops Westfield wrote:

>> 1. You can only have 2 GB under a FAT16 partition. You can partition
>> the disk into volumes (using FDISK plus FORMAT) of 2 GB or less to
>> get it working in DOS.
> The other thing is that you can only have two dos/windows "partitions"
> on a drive.  To get more than two logical disks, you carve up the 2nd
> partition ("extended dos partition") into multiple logical drives.

 I've certainly learned an awful lot already about the system.  Perhaps
that's the important thing!  I have a clue about something I may have
done wrong, apparently the partition identifier is different ($0F) for
extended DOS partitions containing FAT32 than for FAT16 ($05).

 The first absolutely fascinating detail relates to what an extended
DOS partition actually is and why it can contain a virtually unlimited
number of logical drives.  In fact, the extended DOS partition points
to another partition table which contains either one or two entries, the
first being a logical drive (structured and identified as a primary
partition) and the second if present ... another extended partition!

 In other words, it's a chain which is traversed recursively by the
same routines.

> Also, the partition table only has room for 4 partitions total, a
> minor point (since DOS only uses two of them) that drove me crazy when
> I tried to install linux...

 So far, that hasn't worried me.  A typical system contains exactly
four partitions: DOS primary, DOS extended, Linux and Linux swap.  The
most common other Linux data partition you will use will be one or more
of the W95 drives, accessed by Samba.  As I see it anyway.

> (If you don't mind wasting space, you can probably set up your 15G
> drive and only use half of it for dos/etc due to that 8G limitation
> ...)

 It seems that the partition drivers, if set up correctly, will be
happy if each partition is less than 8 GB.  Apparently, the partition
table which can only record a cylinder number up to 1023, will happily
roll over; it uses relative addressing.  While a partition greater than
8 GB could not be represented this way, anything less can and the total
of four can access up to 32 GB.

 I am not sure whether I can get away with my total extended DOS
partition exceeding the 8 GB limit given that the individual "drives"
are much smaller.  It may be that I will have to increase my "C" drive
to 4 GB and install AVR studio and MPLAB in there, and reduce my seven
other drives to 1 GB each.

Ruben Jšnsson wrote:

> secondary drive is D: which is 200M FAT16. The problem is that when I
> boot from my DOS6.22 diskette drive C: disappear and drive D: is now
> C:.  This is a problem since I use DOS for programming and can mostly
> do this under W95 but sometime I need DOS 6.22 (No virtualized
> peripherials) and all my paths in the development environment is
> pointing to D: which now doesn't exist.

 You cannot expect DOS 6.22 to see FAT32 partitions.  But why do you
need it?  DOS 7.1 is from what WIN95 boots, and is a perfectly usable
DOS.  That's what you get, in real mode and without Virtual peripherals
if you either 1} Press F8 as soon as you see "Loading Windows 95" and
select "Command Prompt Only", 2} Select "Restart the computer in MSDOS
mode" from Shutdown or set BootGUI=0 in MSDOS.SYS .  AFAIK, it functions
every bit as good as earlier versions and supports SETVER.
--
 Cheers,
       Paul B.

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