Earth and Geographic Science Courses

Week2 -- Operating Systems

Reading: www.bootdisk.com
Minasi, pg 274-290

outside reference: kb.indiana.edu/data/abwa.html

Terms

operating system	basic level software that controls and computer's hardware, runs programs, interacts with users, and communicates with peripheral devices.

device-driver	A piece of software (program) which communicates with (sends signals to) a device, thus operating (driving) the device.

virtual memory	disk space reserved to be used like RAM (via swapping or paging) whenever the system runs short of memory.

GUI	a Graphical User Interface lets a user interact with the computer via pictures and symbols rather than typed text.

command line	as in command-line interface, where user interacts with the computer via memorized commands which are then typed in, precisely, with a keyboard.

multi-tasking	the ability of an operating system to run several programs simultaneously.

co-operative multi-tasking	the application controlling the cpu must relinquish that control before another application can run.

pre-emptive multi-tasking	the operating system determines which application may have access to the cpu.

filesystem	1) maintains the physical organization of data on disks, through a directory structure. 2) the organization of directories, sub-directories, and files on a partition. Examples include FAT16, FAT32, NTFS, etc...

format	to prepare a disk for storing data, by installing the structure of a given filesystem.

partition	is a subdivision of a disk drive. There are two types: primary partition and extended partitions.

Fault Tolerance	the ability of a system to recover from equipment malfunctions

application	a computer program designed to accomplish a specific task or related set of tasks.

backward compatibility	the task of engineering a new version of a product so that the new version works with previous versions of the product.

protected memory	the ability of an operating system to provide applications with their own area of memory which cannot be accessed by other applications.

A Timeline History of Windows and its variants

1975	Microsoft formed
August 25, 1980	XENIX operating system announced by Microsoft.
August 12, 1981	MS-DOS 1.0 ships with the new IBM Personal Computer
March, 1983	MS-DOS 2.0 ships
November 10, 1983	Microsoft Windows announced
November, 1984	MS-DOS 3.1 available
November 20, 1985	Microsoft Windows 1.0 released
April, 1986	MS-DOS 3.2 ships
April 2, 1987	Microsoft Operating System/2 (MS OS/2) announced, as part of a joint agreement between Microsoft and IBM That same day, Microsoft announces MS-DOS 3.3, Windows 2.0 and Windows /386. These new versions are the first with overlapping windows.
June 28, 1988	Windows /286 and /386 versions 2.1 announced
July, 1988	MS-DOS 4.0 released (ugh)
October 31, 1988	OS/2 1.1 with Presentation Manager ships. David Cutler, formerly of Digital and now working for Microsoft, begins work on Windows NT.
November, 1988	MS-DOS 4.01 shipped to correct 4.0 problems
May 22, 1990	Microsoft releases Windows 3.0. First version of Windows to allow use of memory beyond 640Kb.
October, 1991	Windows NT is displayed publicly at a demo at COMDEX.
October 20, 1991	Windows 3.0 with Multimedia Extensions released.
June, 1991	MS-DOS 5.0 ships.
April 6, 1992	Windows 3.1 released. Adds TrueType fonts and many other features.
October 27, 1992	Windows for Workgroups 3.1 released, adding easier, integrated networking.
March, 1993	MS-DOS 6.0 ships.
August, 1993	Windows NT 3.1 released. It consists of over 6 million lines of code.
November, 1993	MS-DOS 6.2 released.
February 15, 1994	Windows for Workgroups 3.11 released.
March 2, 1994	MS-DOS 6.21 ships with drive compression removed due to a law suit.
April 11, 1994	MS-DOS 6.22 ships with new DriveSpace drive compression.
September 6, 1994	Windows NT 3.5 released. It consists of over 9 million lines of code.
April 20, 1995	Frank Condron's World O'Windows begins operation (sorry, couldn't resist!)
June, 1995	Windows NT 3.51 released. Minor release is to support upcoming Windows 95 programs.
August 24, 1995	Windows 95 released.
August 24, 1996	Windows NT 4.0 released. It consists of over 16 million lines of code.
November, 1996	Windows CE 1.0 released, supporting handheld-PCs
September, 1997	Windows NT 5.0 Beta 1 released.
November, 1997	Windows CE 2.0 released
December, 1997	Windows NT 4.0 Option Pack released
June 25, 1998	Windows 98 released.
July, 1998	Windows CE 2.1 released, supporting palm-sized PCs
August 1998	Windows NT 5.0 Beta 2 released to testers
October 27, 1998	Microsoft announces that Windows NT 5.0 will be renamed "Windows 2000"
April 29, 1999	Windows 2000 Beta 3 released to testers
May 5, 1999	Windows 98 Second Edition released
July, 1999	Windows 2000 Release Candidate 1 released to testers
August 25, 1999	Microsoft and Compaq discontinue all Windows NT/2000 development for the Alpha processor
September 19, 1999	Windows 2000 Release Candidate 2 released to testers
November 17, 1999	Windows 2000 Release Candidate 3 released to testers
November 29, 1999	"Millennium" beta 2, successor to Windows 98SE, sent to beta testers
December 15, 1999	Windows 2000 released to manufacturing (i.e., coding completed)
February 17, 2000	Windows 2000 Professional, Server, and Advanced Server released.

A Feature-based Comparison

Operating System	DOS-based	GUI	Multitasking	Bus-Width	Protected Memory
DOS	of course	NO	none	16-bit	No
Win 3.1	runs on top of DOS	YES	cooperative	16-bit	No
Win95	backward compatibility	YES	cooperative for Win16 preemptive for Win32	32-bit	Yes
Win98	backward compatibility	YES	cooperative for Win16 preemptive for Win32	32-bit	Yes
WinNT 4.0	fresh design	YES	preemptive	32-bit	Yes

Win32 vs. Win16

memory model: Win16 uses segmented memory model, whereas Win32 uses a flat memory model;
multitasking: Win16 uses cooperative multitasking; Win32 uses preemptive multitasking
multithreading: only Win32 supports mulithreading, which allows a program to be broken up into pieces which can be run simultaneously (like separate programs multitasking).

Disk Configurations

SLED -- Single Large Expensive Disk

basic, most common configuration
no partition is larger than size of largest disk

RAID -- Redundant Array of Inexpensive Disks

also referred to as a Stripe Set.
supports RAID level 0 -- striping without parity. (requires minimum of 2 disks).
RAID level 1 -- disk mirroring. (minimum of 2 disks).
level 5 -- striping with parity. (minimum of 3 disks).
a stripe set is referred to by a drive letter

Volume Sets

a drive, or portion of a drive, can be combined with a portion of another physical drive to form a volume set.
the volume can be assigned a drive letter and formatted, just like any other partition.
this can create a storage space larger than any individual disk.
if formattted as NTFS, can be made larger at any time, by adding free space from another disk. This is called expanding the volume
but volume set cannot by reduced in size, except by backing up all data on volume, destroying volume, and recreating.

only stripe set with with parity can be recovered in case of disk failure
others must be rebuilt, with data restored from backups.
since volume sets and stripe sets require multiple disks, the chances of data corruption through disk failure is increased.

Disk Partitions

Primary Partitions

under NT (up to four primary partitions on a disk)
(only primary partition under DOS)
cannot be broken into sub-partitions (logical drives)
only primary partition can be boot partition

Extended Partitions

only 1 per disk. in which case there can be only 3 primary partitions, for a total of 4.
breaks down into logical drives

Logical Drive

subdivision of an extended partition
can create up to 24 logical drives (26 - floppy/system drives
minimum size is 2MB

Free Space

space on a disk that is not part of a partition.
free space can allocated by any other type of partitioning mechanism.

total of 4 partitions possible.
by default, drive letters are assigned first to the primary partitions, then to the extended partition/logical drives.
Disk Administratorcan be used to alter drive letter designations.

Disk Partitioning Tools

fdisk

-- is DOS-based, so can only create 1 primary partition, and 1 extended partition.
-- Windows 95 or later versions allows for FAT32 (enable large disk support)
-- FAT16 supports partitions up to only 2GB.

fdisk screens
fdisk instructions

Disk Administrator

create/delete partitions on a disk
make logical drives
get information about:
- disk partition sizes
- filesystem type and size
- amount of free space available on a disk
alter drive letter assignments
format a partition

formatting and filesystems

low-level format

low-level formatting software available from disk vendor
determines sector size to use, number of tracks, sectors per track, cluster size (block size), etc...

logical format

places a filesystem on a partition

Filesystems

FS Type DOS Win95 NT linux notes

FAT12 supported NO NO NO supports floppies and small disks (16MB)

FAT16 supported supported supported supported disks from 16MB to 2GB

FAT32 supported supported NO NO disks up to 2TB

NTFS NO NO supported NO

FS Type	DOS	Win95	NT	linux	notes
FAT12	supported	NO	NO	NO	supports floppies and small disks (16MB)
FAT16	supported	supported	supported	supported	disks from 16MB to 2GB
FAT32	supported	supported	NO	NO	disks up to 2TB
NTFS	NO	NO	supported	NO

The NTFS filesystem

Enhanced file security: access control via usernames and groups
lazy-write scheme: disk writes are actually performed to a reserved area of memory, not directly to disk. The contents of this reserved area of memory (cache) is written to disk periodically. This improves disk I/O performance considerably.
compression: can be figured to provide automatic compression of files and directories.
journaling: a log of every OS operation is kept so that it's easier to rebuild filesystems after a crash
support for Macintosh files

Basic DOS Commands

Command Syntax Explanation

dir    displays listing of the current directory's files and subdirectories

   dir [filename] display listing for filename only

attrib    displays or changes file attributes
a = archive, r = read-only, h = hidden, s=system

   attrib +h [filename] makes filename a hidden file

   attrib -r -s -h [filename] removes read-only, hidden, and system attributes from filename

copy copy [filename1] [filename2] make a copy of filename1 and store it as filename2

del del [filename] delete filename

edit    very simple text editor
alt key accesses menubar
move around screen via arrow keys
CR activates highlighted menu

format format [x:] format a partition as a FAT16 filesystem

fdisk    an interactive tool for disk partitioning

sys sys [x:] copies the 2 DOS system files (IO.SYS and MSDOS.SYS, plus the command interpreter (shell) COMMAND.COM to the targeted drive

Command	Syntax	Explanation
dir		displays listing of the current directory's files and subdirectories
	dir [filename]	display listing for filename only
attrib		displays or changes file attributes a = archive, r = read-only, h = hidden, s=system
	attrib +h [filename]	makes filename a hidden file
	attrib -r -s -h [filename]	removes read-only, hidden, and system attributes from filename
copy	copy [filename1] [filename2]	make a copy of filename1 and store it as filename2
del	del [filename]	delete filename
edit		very simple text editor alt key accesses menubar move around screen via arrow keys CR activates highlighted menu
format	format [x:]	format a partition as a FAT16 filesystem
fdisk		an interactive tool for disk partitioning
sys	sys [x:]	copies the 2 DOS system files (IO.SYS and MSDOS.SYS, plus the command interpreter (shell) COMMAND.COM to the targeted drive

Commands

convert    --   (NT) convert a filesystem from FAT (16) format to NTFS format.
scandisk    --   (DOS) checks filesystem consistency
chkdsk    --   (DOS) surface scan checking for bad media
chkdsk    --   (NT) combines functionality of DOS chkdsk and scandisk. chkdsk performs surface scan.
showdisk    --    available on NT Resource Kit only

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