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Partitions, Sectors, Cmos, Bios and such:
A real quick story on CMOS= And even a quicker one on BIOS=so I can get
these two things out of the way.
CMOS--Meaning:
Abbreviation of complementary metal oxide semiconductor. Pronounced see-moss, CMOS is a
widely used type of semiconductor. CMOS semiconductors use both NMOS (negative polarity)
and PMOS (positive polarity) circuits. Since only one of the circuit types is on at any
given time, CMOS chips require less power than chips using just one type of transistor.
This makes them particularly
attractive for use in battery-powered devices, such as portable computers. Personal
computers also contain a small amount of battery-powered CMOS memory to hold the date,
time, and system
setup parameters.
BIOS--Meaning:
It's the settings for hard-drive,monitor,software,etc.
You'll have to go to one of the many other sites for a further explanation on all the
variables because someone could write a hundred pages on all the settings and not even
scratch the surface---anyway, I'm trying to stick to the Hard-Drive.
If you want your Windows to run 10 to 26% faster--(Click Here for
set-up page).
Want to know about Partitions and Sectors do you:
Partition management is the act of creating, editing, and deleting partitions, and of
using them to claim access to the resources they contain.
Given the need to be able to stop and restart various pieces of software without losing
access to the hardware, it is clear that locking a partition should not depend on (for
example) having the
run-control running. It makes no sense to unlock a partition whenever the run-control
terminates, only to try to lock it again a few seconds later when the run-control is
restarted! Partition management is therefore independent of the software associated to the
elements contained in the partition. We have used the term 'locking' to describe the act
of claiming a partition for exclusive use. We should now be more explicit. Only one user
may lock a partition at any time. Locking a partition does not depend on the ability to
start any of the software associated with that partition. It does guarantee that no other
user has a locked partition which overlaps with the hardware elements of the partition the
user is locking.
Note that partitions must also be locked before they may be edited.
It is not acceptable that a partition can be changed by one user when another user has
locked it!
Under overlapping partitions mode there are two partitions, each covering the entire
machine, in effect at all times. For this reason, you need to change how you issue rmpart
and lspart commands.
To remove a partition named mypart1234, type:
xps35% rmpart .interactive.mypart1234
To list current partitions, type:
xps35% lspart -r .compute
Partition Matrix Columns
The partition matrix has four columns that define a partition:
Type=An editable column that displays the type of partition. The acceptable values for
this field are:
bsd - a partition for a BSD version 4.2 filesystem.
efs - a partition for an Extent Filesystem.
lvol - a partition that is to be part of a logical volume.
raw - a raw partition that can be used by the kernel for swap space. A root or user/root
disk should have a raw partition in partition 0 for swap space. See the IRIX Admin: System
Configuration and Operation guide for more information on swap space.
rlvol - a raw logical volume partition.
sysv - a partition for a UNIX System V filesystem.
xfs - a partition for an XFS filesystem.
xfslog - a partition for an XFS filesystem log.
xlv - a partition for an XFS logical volume.
Start=The place on the disk at which a partition begins.
Size=The size of the partition.
End=The location of the end of the partition.This field is computed by xdkm based on the
start location and the size of the partition.
Sectors of Sorts:
Sectors are not files but simply small areas on your disk that your /hardware reads in
single
chunks. Under DOS, sectors are most commonly 512 bytes in length. These sectors are
invisible to
normal programs but are vital for correct operation of your PC. You can not see system
sectors on
your diskette in the same way that you can see files. They are simply a special reserved
location at
the beginning of your diskette.
DOS Boot Sectors:
The very first sector on disk or diskette that DOS is aware of is the boot sector. From a
DOS
perspective, this is the first sector on the disk. Every floppy and hard disk has a boot
sector
containing executable code. This sector contains an executable program whether the disk is
bootable or not. Since this program is executed every time you power on or boot your PC,
it is very
vulnerable to virus attack. Damage to this sector can make your disk appear to be
unreadable.
This sector is rewritten whenever you do a "SYS" or a "FORMAT /S" to a
disk.
Warning: even a non-bootable floppy can contain a virus in the boot sector. If you leave
the floppy
in your PC when you power on or boot, you will be infected even though the PC won't
successfully
boot from that floppy.
Partition Sector (AKA Master Boot Record or MBR)
On hard (fixed) disk drives, the very first sector is the partition sector (also known as
the master boot record or partition table).
Each physical hard disk drive has one of these sectors. A single physical disk can be
partitioned into one or more logical disks.
For example, you may have a physical drive partitioned into C: and D: logical disks so
that your single physical disk appears (to DOS) to be two logical disks. The single
partition sector contains the information that describes both logical disks. If the
partition sector is damaged, then DOS may not even recognize that your disk exists.
The partition sector also contains a program which is executed every time you power up
or boot your PC.
This program executes and reads the DOS boot sector (or other operating system boot
sector) which also contains a program. Numerous viruses plant their code in the partition
sector. Also see NERD & KERNEL pages for more info. on MBR.
Want More MBR stuff: Click Here OR Here:
The Case Of the Phantom Drives in W95's DOS:
WIN95 FDISK may use new partition types which makes drive unaccessible by DOS 6.x and may
also cause "phantom" drives and data loss.
1 - WIN95 FDISK Shows PRI or EXT DOS Partition, DOS 6.x Shows NON-DOS
Windows 95's FDISK can use 2 new partition types - type 0Eh (Primary DOS) and type 0Fh
(extended DOS). WIN95 FDISK will use these partition types only under these circumstances
-(1) the drive supports LBA, (2) the BIOS supports LBA when communicating with the drive,
and (3) the BIOS supports INT13 Extensions (which allows LBA support on the software side
of the BIOS).
Most modern IDE or EIDE hard drives over 500MB support LBA. Phoenix BIOSes support LBA
starting with version 4.03 of the base code. Phoenix BIOSes support INT13 extensions
starting with
version 4.04 of the base code. See our article titled "Notes on LBA" (
http://www.firmware.com/pb4ts/lba.htm ) for more information on LBA and INT13 extensions.
These new partition types are mentioned in a Microsoft KnowledgeBase article - Q69912 -
"MS-DOS Partitioning Summary". This article can be found at this URL:
http://www.microsoft.com/kb/articles/q69/9/12.htm
If WIN95 assigns type E or type F to a partition, it will not be accessible by any DOS
version prior to DOS 7 (WIN95 DOS). FDISK from MS-DOS 6.22 or earlier will show such
partitions as NON-DOS.
This problem can be prevented or solved in 2 ways - (1) partition the drive with DOS 6.x
FDISK and then install or reinstall WIN95, or (2) use the /X parameter with WIN95's
FDISK, which will prevent it from using types E and F. In either case, type 6 will be used
instead of type E for a Primary DOS partition and type 5 will be used instead of type F
for an Extended DOS partition.
This may possibly cause some performance loss on the drive. There may be no reason why
some systems need to be accessed with older DOS versions, in which case this would not be
a reason to remove or prevent the use of the new partition types. However, there are other
problems that can be caused when these partition types are used. This is described in the
following section.
2 - "Phantom" Drives and Potential for Massive Data Corruption
Upon investigating calls from some of our customers reporting extra drive letters and
duplicate drives under Windows 95, we discovered some problems caused by a bug in
the way that WIN95 was handling drives that were assigned the new partition types.
Problems such as extra drive letters, duplicate drives, and data corruption can occur
under certain circumstances. This may be limited to drives that have been partitioned
into primary and extended partitions and seems to be associated with switching between
WIN95 and MS-DOS mode.
We contacted Microsoft in March of 1996 and were told that they were already aware of
this problem and that it would be addressed soon. Shortly thereafter, an article
explaining the problem appeared in the Microsoft KnowledgeBase - Q148821 -"Possible
Data Loss with LBA and INT13 Extensions". This article can be found at this
URL:http://www.microsoft.com/kb/articles/q148/8/21.htm A replacement driver to fix the
problem appeared on Microsoft's web site on June 27, 1996. DSKTSUPD.EXE can be obtained at
this URL
-http://www.microsoft.com/kb/softlib/mslfiles/DSKTSUPD.EXE This file will automatically
update the driver DISKTSD.VXD in the WINDOWS\SYSTEM\IOSUBSYS directory. Old version of
DISKTSD.VXD is 16478 bytes, dated 7-11-95 9:50a, new version is 16514 bytes, dated 3-22-96
9:52a.
These problems can also be prevented by using DOS 6.22 (or earlier) FDISK to partition
hard drives prior to installing WIN95 or by using the /X parameter with WIN95's FDISK,
which will prevent it from assigning type E or F to any partitions.
Note - the original version of this article was much longer, containing details on how
we duplicated the problem and DEBUG scripts to check and change partition types.
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