Difference between pages "FAT" and "Palm"

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(Added Information About Wasted Sectors)
 
(3Com Audrey)
 
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=Technical Overview=
+
__TOC__
  
FAT, or file allocation table, is a file system that is designed to keep track of allocation status of clusters on a hard drive.  Developed in 1977 by Microsoft Corporation, FAT was originally intended to be a file system for the Microsoft Disk BASIC interpreter.  FAT was quickly incorporated into an early version of Tim Patterson's QDOS, which was a moniker for "Quick and Dirty Operating System". Microsoft later purchased the rights to QDOS and released it under Microsoft branding as PC-DOS and later, MS-DOS. 
+
=Overview=
  
==File Allocation Table Structure==
+
A "Palm" is a commonly referred to as a small-scale (hand-held) computer that runs Palm's PalmOS software. 
  
[[Image:Yale fat16 diagram.jpg|frame|Basic layout of the FAT16 file system.]]
+
== History ==
The FAT file system is composed of several areas:
+
  
* Boot Record or Boot Sector
+
Palm Computing was founded by Jeff Hawkins, Donna Dubinsky and Ed Colligan. The original purpose of the company was to create handwriting recognition software for other devices (Graffiti). The initial idea for the devices came from Hawkins' habit of carrying a block of wood in his pocket.
* FATs
+
*  Root Directory or Root Folder
+
*  Data Area
+
*  Clusters
+
*  Wasted Sectors
+
  
'''Boot Record'''
+
The initial Palm device released in 1996 was called the Pilot.  Because Pilot Pen Corporation brought forth a trademark infrigement case, the second generation device released in 1997 was named the PalmPilot. 
  
When a computer is powered on, a POST (power-on self test) is performed, and control is then transferred to the MBR (Master Boot Record).  The MBR is present no matter what file system is in use, and contains information about how the storage device is logically partitioned.  When using a FAT file system, the MBR hands off control of the computer to the Boot Record, which is the first sector on the partitionThe Boot Record, which occupies a reserved area on the partition, contains executable code, in addition to information such as an OEM identifier, number of FATs, media descriptor (type of storage device), and information about the operating system to be booted.  Once the Boot Record code executes, control is handed off to the operating system installed on that partition.
+
The Palm was not the original PDA device released, but benefited from the failure of Apple's Newton.   
  
'''FATs'''
+
The Palm OS initially featured personal information management (PIM) tools such as Calendar, Contacts, Memo Pad, Expense and Tasks. 
  
The primary task of the FATs is to keep track of the allocation status of clusters, or logical groupings of sectors, on the disk drive.  There are four different possible FAT entries: allocated (along with the address of the next cluster associated with the file), unallocated, end of file, and bad sector.  
+
Presently, version 6.0 of the Palm OS is under development (Cobalt).  Cobalt features a Linux-based kernel.  There are presently no devices released using Palm OS 6.  
  
In order to provide redundancy in case of data corruption, two FATs, FAT1 and FAT2, are stored in the file system.
+
=Features=
 +
<table>
 +
<tr>
 +
<td>'''Address Book''': Allows the user to keep track of their contacts.  Synchronized via HotSync manager</td>
 +
</tr>
 +
<tr>
 +
<td>'''Calculator''': Basic 4 function calculator</td>
 +
</tr>
 +
<tr>
 +
<td>'''Datebook''': Track appointments, birthdates and other important times during the year.  Synchronized via HotSync manager</td>
 +
</tr>
 +
<tr>
 +
<td>'''Expenses''': Keep track of your spending habits.</td>
 +
</tr>
 +
<tr>
 +
<td>'''HotSync''': Application that ran on your desktop or portable PC or Mac to allow for calendars and contacts to easily be synchronized with Palm device.</td>
 +
</tr>
 +
<tr>
 +
<td>'''Memo Pad''': Write short notes.</td>
 +
</tr>
 +
<tr>
 +
<td>'''Note Pad''': Scribble notes in your natural writing language.</td>
 +
</tr>
 +
<tr>
 +
<td>'''To Do List''': Create a check list of items to accomplish.  Synchronized via HotSync manager.</td>
 +
</tr>
 +
<tr>
 +
<td>'''Palm Photos''': Photo manager that allows sharing of photos between multiple palm devices.</td>
 +
</tr>
 +
</table>
  
'''Root Directory'''
+
=Palm Variants=
  
The Root Directory, sometimes referred to as the Root Folder, contains an entry for each file and directory stored in the file system. This information includes the file name, starting cluster number, and file size.  This information is changed whenever a file is created or subsequently modified. Root directory has a fixed size of 512 entries on a hard disk and the size on a floppy disk depends.
+
-Version 3.1, 3.3, 3.5
 +
Added support for color, multiple expansion ports, new processors, etc.
  
'''Data Area'''
+
-Version 4.0
 +
Added a standard interface for external FS access
  
The Boot Record, FATs, and Root Directory are collectively referred to as the System Area. The remaining space on the logical drive is called the Data Area, which is where files are actually stored. It should be noted that when a file is deleted by the operating system, the data stored in the Data Area remains intact until it is overwritten.
+
-Version 5.0
 +
First version to support Acorn Risc Machine (ARM) devices. Later versions which included OS 4.1.2 and 5.2, featured Graffiti 2. It began the separation of Palm OS and Palm One.
  
'''Clusters'''
+
-Version 6
 +
Allowed ARM applications with multimedia support.
  
In order for FAT to manage files with satisfactory efficiency, it groups sectors into larger blocks referred to as clusters. A cluster is the smallest unit of disk space that can be allocated to a file, which is why clusters are often called allocation units. Cluster size is determined by the size of the disk volume and every file must be allocated an even number of clusters. Cluster sizing has a significant impact on performance and disk utilization. Larger cluster sizes result in more wasted space because files are less likely to fill up an even number of clusters.
+
==Palm Pilot==
  
A cluster ranges in size from 4 sectors (2,048 bytes) to 64 sectors (32,768 bytes). The sectors in a cluster are continuous, therefore each cluster is a continuous block of space on the disk.
+
==3Com Audrey==
  
'''Wasted Sectors'''
+
The 3Com Audrey was created to be a kitchen computer in 2000-2001.  It was a mainly a used to access the Internet.  Cisco then bought out 3Com and the Audrey was no more.  One noticeable aspect of the Audrey is how people can hack it.  They have turned it into anything from a web server to a chatting client.  It runs QNX with PalmOS extensions.  This allows it to be hacked extremely easily.
  
Wasted Sectors are a result of the number of data sectors not being evenly distributed by the cluster size. It's made up of unused bytes left at the end of a file. Small files on a hard drive are the reason for wasted space and the bigger the hard drive the more wasted space there is.
+
It runs on the Intel-compatible Cyrix-MediaGX processor. It uses Palm's HotSync technology to update the address book and date book with up to two Palms simultaneously. It uses a USB Ethernet controller to connect to the Internet.  It also has built-in stereo speakers to play digital and streaming music.  You can either use the clear pen to input data, or pull out the wireless keyboard.  No graffiti is used.
  
==Versions==
+
It was discontinued on March 21, 2001.  However, there is still an Audrey frenzy going on today.
  
There are three variants of FAT in existence: FAT12, FAT16, and FAT32.
+
==Fossil==
  
'''FAT12'''
+
==Garmin==
<br />
+
*  FAT12 is the oldest type of FAT that uses a 12 bit file allocation table entry. 
+
*  FAT12 can hold a max of 4,086 clusters (which is 2<sup>12</sup> clusters minus a few values that are reserved for values used in  the FAT). 
+
*  It is used for floppy disks and hard drive partitions that are smaller than 16 MB. 
+
*  All 1.44 MB 3.5" floppy disks are formatted using FAT12.
+
*  Cluster size that is used is between 0.5 KB to 4 KB.
+
  
'''FAT16'''
+
==Kyocera==
<br/>
+
*  It is called FAT16 because all entries are 16 bit.
+
*  FAT16 can hold a max of 65,536 addressable units (2 <sub>26</sub>
+
*  It is used for small and moderate sized hard disk volumes.
+
*  The actual capacity is 65,525 due to some reserved values
+
  
'''FAT32'''
+
==QualComm==
<br />
+
FAT32 is the enhanced version of the FAT system implemented beginning with Windows 95 OSR2, Windows 98, and Windows Me.
+
Features include:
+
*  Drives of up to 2 terabytes are supported (Windows 2000 only supports up to 32 gigabytes)
+
*  Since FAT32 uses smaller clusters (of 4 kilobytes each), it uses hard drive space more efficiently. This is a 10 to 15 percent improvement over FAT or FAT16.
+
*  The limitations of FAT or FAT 16 on the number of root folder entries have been eliminated. In FAT32, the root folder is an ordinary cluster chain, and can be located anywhere on the drive.
+
*  File allocation mirroring can be disabled in FAT32. This allows a different copy of the file allocation table then the default to be active.
+
<br />
+
'''Comparison of FAT Versions'''
+
  
Table adapted from:
+
==Samsung==
http://en.wikipedia.org/wiki/File_Allocation_Table
+
  
 +
==Sony Cli&Egrave;==
  
<table cellpadding="2" border="1">
+
==Symbol==
<tr bgcolor="lightgreen" align="center">
+
<td bgcolor="white"></td>
+
<td><b>FAT12</b></td>
+
<td><b>FAT16</b></td>
+
<td><b>FAT32</b></td>
+
  
</tr>
+
==TapWave==
<tr align="center">
+
<th bgcolor="lightgrey">Developer</th>
+
<td colspan="3">Microsoft</td>
+
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey" rowspan="2">Full Name</th>
+
<td colspan="3">File Allocation Table</td>
+
</tr>
+
<tr align="center">
+
<td>(12-bit version)</td>
+
<td>(16-bit version)</td>
+
  
<td>(32-bit version)</td>
+
==TRG==
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey">Introduced</th>
+
<td>1977 (Microsoft Disk BASIC)</td>
+
<td>July 1988 (MS-DOS 4.0)</td>
+
  
<td>August 1996 (Windows 95 OSR2)</td>
+
==Handspring Visor==
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey">Partition identifier</th>
+
<td>0x01 (MBR)</td>
+
<td>0x04, 0x06, 0x0E (MBR)</td>
+
  
<td>0x0B, 0x0C (MBR)<br />
+
The original creators of the PalmPilot, Jeff Hawkins, Donna Dubinsky, and Ed Colligan, left Palm Computing after desputes with the parent company 3com. As a result, the trio founded Handspring in 1998. The first product released in 1999 was called the Handspring Visor, a clone of the original PalmPilot with minor additions, that used the newly created Palm OS. One of it's most prominent features was USB support and an expansion slot for memory cards, both of which were not yet popular at the time.
<small>EBD0A0A2-B9E5-4433<br />
+
-87C0-68B6B72699C7</small> (GPT)</td>
+
</tr>
+
<tr bgcolor="lightgreen" align="center">
+
<th>Structures</th>
+
<th><b>FAT12</b></th>
+
  
<th><b>FAT16</b></th>
+
The Visor line includes:
<th><b>FAT32</b></th>
+
<ul>
</tr>
+
<li>Visor and Visor Deluxe</li>
<tr align="center">
+
<li>Visor Prism</li>
<th bgcolor="lightgrey">Directory contents</th>
+
<li>Visor Platinum</li>
<td colspan="3">Table</td>
+
<li>Visor Edge</li>
</tr>
+
<li>Visor Neo</li>
<tr align="center">
+
<li>Visor Pro</li>
<th bgcolor="lightgrey">File allocation</th>
+
</ul>
<td colspan="3">Linked List</td>
+
</tr>
+
  
<tr align="center">
+
==Treo==
<th bgcolor="lightgrey">Bad blocks</th>
+
-Treo 600
<td colspan="3">Linked List</td>
+
Is a smartphone that combines the color of Palm OS PDA with a mobile phone.
 +
<table border="1">
 +
<th>Key Features</th>
 +
<tr>
 +
<td>Batteries</td>
 +
<td>Built in rechargeable lithium ion batteries</td>
 
</tr>
 
</tr>
<tr bgcolor="lightgreen" align="center">
+
<tr>
<th>Limits</th>
+
<td>Storage</td>
<th><b>FAT12</b></th>
+
<td>32MB Ram</td>
<th><b>FAT16</b></th>
+
<th><b>FAT32</b></th>
+
 
</tr>
 
</tr>
<tr align="center">
+
<tr>
 
+
<td>Memory Slots</td>
<th bgcolor="lightgrey">Max file size</th>
+
<td>SDIO, SD, MMC</td>
<td>32 MiB</td>
+
<td>2 GiB </td>
+
<td>4 GiB</td>
+
 
</tr>
 
</tr>
<tr align="center">
+
<tr>
<th bgcolor="lightgrey">Max number of files</th>
+
<td>Communications</td>
<td>4,077</td>
+
<td>Infrared comm port</td>
<td>65,517</td>
+
<td>268,435,437</td>
+
 
</tr>
 
</tr>
<tr align="center">
+
<tr>
<th bgcolor="lightgrey">Max filename size</th>
+
<td>MP3 and Headset Support</td>
<td colspan="3">8.3 or 255 characters when using LFNs</td>
+
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey">Max volume size</th>
+
<td>16 MiB</td>
+
<td>2 GiB for all (4 GiB for some)</td>
+
<td>32 GiB for all OS (2 TiB for some)</td>
+
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey">Max clusters</th>
+
<td>4080</td>
+
<td>65520</td>
+
<td>4177918</td>
+
</tr>
+
<tr bgcolor="lightgreen" align="center">
+
<th>Features</th>
+
<th><b>FAT12</b></th>
+
<th><b>FAT16</b></th>
+
<th><b>FAT32</b></th>
+
 
</tr>
 
</tr>
 +
</table>
  
<tr align="center">
+
<table>
<th bgcolor="lightgrey">Dates recorded</th>
+
<th>References:</th>
<td colspan="3">Creation, modified, access</td>
+
<tr>
 +
<td>http://www.answers.com/topic/palm-os</td>
 
</tr>
 
</tr>
<tr align="center">
+
<tr>
<th bgcolor="lightgrey">Date range</th>
+
<td>http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Treo+600&gwp=8&curtab=2222_1&linktext=Treo%20600</td>
<td colspan="3">January 1, 1980 - December 31, 2107</td>
+
 
+
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey">Forks</th>
+
<td colspan="3">Not natively</td>
+
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey">Unicode File Names</th>
+
<td colspan="3">System Character Set</td>
+
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey">Attributes</th>
+
<td colspan="3">Read-only, hidden, system, volume label, subdirectory, archive</td>
+
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey">Permissions</th>
+
<td colspan="3">No</td>
+
 
+
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey">Transparent compression</th>
+
<td colspan="2">Per-volume, Stacker, DoubleSpace, DriveSpace</td>
+
<td>No</td>
+
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey">Transparent encryption</th>
+
 
+
<td colspan="2">Per-volume only with DR-DOS</td>
+
<td>No</td>
+
</tr>
+
<tr bgcolor="lightgreen" align="center">
+
<th>Overall Performance</th>
+
<th><b>FAT12</b></th>
+
<th><b>FAT16</b></th>
+
<th><b>FAT32</b></th>
+
</tr>
+
 
+
<tr align="center">
+
<th bgcolor="lightgrey">Fault Tolerance</th>
+
<td>Minimal</td>
+
<td colspan="2">Average</td>
+
</tr>
+
<tr align="center">
+
<th bgcolor="lightgrey">Disk Space Economy</th>
+
<td>Average</td>
+
<td>Minimal on large volumes</td>
+
<td>Max</td>
+
 
</tr>
 
</tr>
 
</table>
 
</table>
<br/>
 
==Applications of FAT==
 
 
Due to its low cost, mobility, and non-volatile nature, flash memory has quickly become the choice medium for storing and transferring data in consumer electronic devices. The majority of flash memory storage is formatted using the FAT file system.  In addition, FAT is also frequently used in electronic devices with miniature hard drives.
 
 
Examples of devices in which FAT is utilized include:
 
 
* USB thumb drives
 
* Digital cameras
 
* Digital camcorders
 
* Portable audio and video players
 
* Multifunction printers
 
* Electronic photo frames
 
* Electronic musical instruments
 
* Standard televisions
 
* PDAs
 
 
=Forensics Issues=
 
==Data Recovery==
 
Recovering directory entries from FAT filesystems as part of [[recovering deleted data]] can be accomplished by looking for entries that begin with a sigma 0xe5. When a file or directory is deleted under a FAT filesystem, the first character of its name is changed to sigma. The remainder of the directory entry information remains intact.
 
 
The pointers are also changed to zero for each cluster used by the file.  Recovery tools look at the FAT to find the entry for the file.  The location of the starting cluster will still be there.  It is not deleted or modified.  The tool will go straight to that cluster and try to recover the file using the file size as a determinant.  Some tools will go to the starting cluster and recover the next "X" number of clusters needed for the specific file size.  However, this tool is not ideal.  An ideal tool will locate "X" number of available clusters.  Since files are most often fragmented, this will be a more precise way to recover the file.
 
 
An issue arises when two files in the same row of clusters are deleted.  If the clusters are not in sequential order, the tool will automatically receive "X" number of clusters.  However, because the file was fragmented, it's most likely that all the clusters obtained will not all contain data for that file.  If these two deleted files are in the same row of clusters, it is highly unlikely the file can be recovered.
 
 
==File Slack==
 
File slack is data that starts from the end of the file written and continues to the end of the sectors designated to the file.    There are two types of file slack, RAM slack, and Residual slack.  RAM slack starts from the end of the file and goes to the end of that sector.  Residual slack then starts at the next sector and goes to the end of the cluster allocated for the file.  File slack is a helpful tool when analyzing a hard drive because the old data that is not overwritten by the new file is still in tact. Go to http://www.pcguide.com/ref/hdd/file/partSizes-c.html for examples.
 
 
<br/>
 
 
'''References:'''
 
----
 
 
http://en.wikipedia.org/wiki/File_Allocation_Table
 
 
http://www.microsoft.com
 
 
http://www.ntfs.com
 
 
http://www.ntfs.com/ntfs_vs_fat.htm
 
 
http://support.microsoft.com/kb/q154997/#XSLTH3126121123120121120120
 
 
http://www.dewassoc.com/kbase/hard_drives/boot_sector.htm
 
 
http://www2.tech.purdue.edu/cpt/courses/cpt499s/
 

Revision as of 15:20, 15 February 2006

Overview

A "Palm" is a commonly referred to as a small-scale (hand-held) computer that runs Palm's PalmOS software.

History

Palm Computing was founded by Jeff Hawkins, Donna Dubinsky and Ed Colligan. The original purpose of the company was to create handwriting recognition software for other devices (Graffiti). The initial idea for the devices came from Hawkins' habit of carrying a block of wood in his pocket.

The initial Palm device released in 1996 was called the Pilot. Because Pilot Pen Corporation brought forth a trademark infrigement case, the second generation device released in 1997 was named the PalmPilot.

The Palm was not the original PDA device released, but benefited from the failure of Apple's Newton.

The Palm OS initially featured personal information management (PIM) tools such as Calendar, Contacts, Memo Pad, Expense and Tasks.

Presently, version 6.0 of the Palm OS is under development (Cobalt). Cobalt features a Linux-based kernel. There are presently no devices released using Palm OS 6.

Features

Address Book: Allows the user to keep track of their contacts. Synchronized via HotSync manager
Calculator: Basic 4 function calculator
Datebook: Track appointments, birthdates and other important times during the year. Synchronized via HotSync manager
Expenses: Keep track of your spending habits.
HotSync: Application that ran on your desktop or portable PC or Mac to allow for calendars and contacts to easily be synchronized with Palm device.
Memo Pad: Write short notes.
Note Pad: Scribble notes in your natural writing language.
To Do List: Create a check list of items to accomplish. Synchronized via HotSync manager.
Palm Photos: Photo manager that allows sharing of photos between multiple palm devices.

Palm Variants

-Version 3.1, 3.3, 3.5 Added support for color, multiple expansion ports, new processors, etc.

-Version 4.0 Added a standard interface for external FS access

-Version 5.0 First version to support Acorn Risc Machine (ARM) devices. Later versions which included OS 4.1.2 and 5.2, featured Graffiti 2. It began the separation of Palm OS and Palm One.

-Version 6 Allowed ARM applications with multimedia support.

Palm Pilot

3Com Audrey

The 3Com Audrey was created to be a kitchen computer in 2000-2001. It was a mainly a used to access the Internet. Cisco then bought out 3Com and the Audrey was no more. One noticeable aspect of the Audrey is how people can hack it. They have turned it into anything from a web server to a chatting client. It runs QNX with PalmOS extensions. This allows it to be hacked extremely easily.

It runs on the Intel-compatible Cyrix-MediaGX processor. It uses Palm's HotSync technology to update the address book and date book with up to two Palms simultaneously. It uses a USB Ethernet controller to connect to the Internet. It also has built-in stereo speakers to play digital and streaming music. You can either use the clear pen to input data, or pull out the wireless keyboard. No graffiti is used.

It was discontinued on March 21, 2001. However, there is still an Audrey frenzy going on today.

Fossil

Garmin

Kyocera

QualComm

Samsung

Sony CliÈ

Symbol

TapWave

TRG

Handspring Visor

The original creators of the PalmPilot, Jeff Hawkins, Donna Dubinsky, and Ed Colligan, left Palm Computing after desputes with the parent company 3com. As a result, the trio founded Handspring in 1998. The first product released in 1999 was called the Handspring Visor, a clone of the original PalmPilot with minor additions, that used the newly created Palm OS. One of it's most prominent features was USB support and an expansion slot for memory cards, both of which were not yet popular at the time.

The Visor line includes:

  • Visor and Visor Deluxe
  • Visor Prism
  • Visor Platinum
  • Visor Edge
  • Visor Neo
  • Visor Pro

Treo

-Treo 600 Is a smartphone that combines the color of Palm OS PDA with a mobile phone.

Key Features
Batteries Built in rechargeable lithium ion batteries
Storage 32MB Ram
Memory Slots SDIO, SD, MMC
Communications Infrared comm port
MP3 and Headset Support
References:
http://www.answers.com/topic/palm-os
http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Treo+600&gwp=8&curtab=2222_1&linktext=Treo%20600