Mary:

OK. So, can a FAT32 system address twice as much HDD space? Also, my Mom
has a Pentium100 system with Win98SE (FAT32) and her 4.2G HDD is fully
accesible. We have an AMD K6-2/350 with a 17G HDD, partitioned from 2.0
to 8.5.G - all functional (WinME, FAT32). We haven't added a Promise or
Ultra controller, etc. Please explain.

Jack

On Wed, 30 May 2001 02:28:22 -0500 Mary Wolden <[log in to unmask]>
writes:
> From: "Jack R Payton" :Sent: Wednesday, May 30, 2001 1:11 AM
> Subject: Re: [PCBUILD] Replacing Hard Drive

> > Mary:
> >
> > Depite my abject admiration for your computer knowledge, I
> question the
> > idea that a harddrive, no matter how large, cannot be partitioned
> - with
> > Windows or a program such as Partition Magic - into chunks of
> readable
> > size by the OS and/or BIOS. My understanding is (was?) that one
> way or
> > another, a harddrive can be partitioned into chunks readable by
> the
> > OS/BIOS. Please elucidate.
> >
> > YOU:
> > "Jack - For you to be able to partition the hard drive into sizes
> equal
> > or less than the BIOS limitation the BIOS must be able to
> recognize the
> > entire drive.  The BIOS limitation of 8.4 g means that the BIOS
> can't
> > recognize any part of the drive past the 8.4 g, therefore you
> would not
> > be able to access it to partition it.
> >    "If there is not a BIOS upgrade, you could also add a Promise
> hard
> > drive controller, Ultra 100 or Ultra 66, that would support the
> faster
> > speeds of the larger hard drives now."
> >
> > Mary Wolden
> >
>
> Jack,
>
> Here is a quote from Western Digital explaining hard drive
> limitations.  I hope this helps you understand.
>
> "The amount of space available to store information on hard drives
> is constantly increasing. Computer operating systems and system
> BIOSs have limitations that are related to specific hard drive
> capacities. Three capacity points that can affect how your operating
> system and system BIOS support your hard drive are 8.4 GB, 2.1 GB,
> and 528 MB.
>
> The limitations of your system BIOS and your operating system
> combined determine your overall system limitation. For example, if
> your operating system recognizes extended BIOS functions, but your
> system BIOS has a 2.1 GB drive barrier, you are limited to your
> system BIOS's 2.1 GB drive barrier. Conversely, if your operating
> system does not recognize extended BIOS functions, but your system
> BIOS supports 8.4 GB hard drives, you are limited to your operating
> system's capability. Your system limitation is based on the lowest
> functioning barrier."
>
> These limitations apply to any hard drive that reports an EIDE
> capacity of 16320 cylinders x 16 heads x 63 sectors per track or
> larger.  INT 13 Function 8 is the traditional method used by the
> system BIOS to access hard drives using CHS (cylinders, heads and
> sectors per track).  The maximum values the BIOS can report (1024
> cylinders, 255 heads and 63 sectors) have been exceeded by the 8.4
> GB and larger hard drives.  Since conventional INT 13 functions use
> 24 bits to represent addresses, this traditional CHS method permits
> 8.4GB ( 2(24th)* 512 bytes/sector) to be addressed. To utilize the
> full capacity of hard drives larger than 8.4 GB, the system BIOS
> must use extended INT 13 functions and LBA method of addressing.
> Extended INT 13 functions use 32 bits to represent addresses.  LBA
> addressing passes a single parameter to represent the address.  An
> ATA hard disk can accept a single address of 28 bits, so the LBA
> method of addressing allows addressing of 137.4 GB.
>
> If both your BIOS and motherboard do not support extended BIOS
> functions your drive, no matter how large it is, the drive will only
> be recognized at the lowest limit of either the BIOS or the OS.
>
> I believe what you are referring to is neither the correct BIOS nor
> drivers can overcome limitations inherent in operating systems. For
> example, in Windows 3.1x and early versions of Windows 95, 16 bits
> are available for cluster addressing in the file allocation table
> (thus the term, FAT16). Since each address specifies a cluster of up
> to 32KB, the maximum partition size is 2.1GB. So while hard disk
> drives larger than 8.4GB can be used with these FAT16 operating
> systems, multiple partitions no larger than 2.1GB each are required.
>
> Mary Wolden

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