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=Managing your Computer Desktop=

[[Image:meta1.jpg|right|thumb|Organisation of files]]This course is all about managing '''data/information/knowledge''' with the help of  computers. 
They do so with the help of an: 
#<big class="c1">Operating System (OS)</big>, examples of which include:
##Microsoft Windows: Windows 7.
##Unix: Mac OS X, Redhat Linux
##Mobile devices/SmartPhones:  Symbian,  Windows  Mobile,  Android,  iOS (+ iTunes)
# '''Access''' to which is controlled by authentication against ''User names/passwords'' and  via  Web-pages by the same authentication, and which serves to identify the author/curator of data and information so created.
# '''Organisation:''' is historically be a metaphor based on  '''Files''' or Documents which are  located in Hierarchical Folders (Directories). Directories referred to as '''''Home''''' or '''''My documents''''' have special status for each authenticated user.
#* '''Files:''' adopt naming convention can use up to 256 characters, but with some caveats:
##do not use characters such as '''space, $, /, :, ? '''. 
##If you are tempted to use a space, use the  '''underscore''' _ instead!
##On Linux (only), Filenames are '''''case sensitive'''''. Often the cause of much confusion!
#* '''File Content/Data type:''' is normally (approximately) indicated by adding a 2-4 character extension after a period (.docx) to the name. 
##This extension [[image:tree2.jpg|thumb|right]] may or may not be ''visible''. Chemical files reserve  ~8 different extensions, so you may end up with up to 8 files with apparently the same name!
##Special types of file, used by the operating system, may be invisible by virtue of their name starting with a period. 
##The (free text) content of  a file may have been ''indexed'' and hence may become  [[image:search3.jpg|right|thumb]] searchable by the utilities provided by the operating system.
#* '''File Metadata (Properties):''' Creation/Modification Dates, sizes, access permissions, "ownership", content, etc is also organised by the OS. 
#* '''File Location''' is in a  hierarchy and is located by searches using file metadata as criteria.
#'''File Size:''' In "bytes" (approximately, 1 character = 1 byte, sometimes 2 bytes). 10<sup>6</sup> bytes =~1 Mbyte, 10<sup>9</sup> bytes = ~1 Gbyte, 10<sup>12</sup> bytes = ~1 Tbyte. Maximum size for any file normally 2 Gbyte (Windows) or very much larger (Linux, Mac OS X).
# '''File Archives:''' A collection of Folders and Files which preserves the hierarchy and file metadata (.zip, .tar). A '''.docx''' file is in fact a (zip) archive
# [[Image:tree.jpg|right|thumb]]'''File Storage (''enterprise'' environment)'''
#* '''Permanent Data Storage,''' as files on:
#** Network Drives:
#**# Drive '''H'''  '''H'''ome directory (Desktop icon ''Home'', capacity 1 Gbytes per user)
#**# Drive '''L:''' "Home" on '''L'''inux systems
#**# Drive '''M:''' Storage area for bibliographic libraries such as '''M'''endeley.
#**# Drive '''R:''' Where files from departmental NM'''R''' Spectrometers are placed (read-only)
#**# Drive '''Z:''' Chemistry data-silo for temporary storage.
#** Local Hard Drive C:  Not to be  used except for temporary storage.
#** Removable media: memory sticks, iPods, CD-RW/DVD (capacity 1-120 Gbyte)
#* '''Temporary Data Storage,''' as
#** "clipboard" in "System Memory" (capacity not known by user, but probably < 10 Mbyte)
#** cache or temporary files, not normally seen by the user but can wreak havoc if corrupt!
# '''File Usage:''' Data Files are created and exchanged using:
#* '''Combinations of programs''', typically a Word processor (Word), a chemical drawing program ([http://www.cambridgesoft.com/products/family.cfm?FID=2 Chemdraw]) and Bibliographic database ([http://www.endnote.com/ EndNote]/[http://www.mendeley.com Mendeley]).
#* '''Data exchange''' between these programs using copy/paste via ''clipboards'' or via files (''drag-n-drop'', ''save/open'' or ''sync'').
<!--# '''File Data Structures:''' Internal structure of files can be ''hidden'' or ''exposed''.
#* '''Hidden''' (binary or clipboard) formats are normally understood only by specific programs and are not meant for humans.  Examples include .docx (Office), .GIF, .PNG, .JPEG (Graphics), .MPEG (audio, video), .PDF (Acrobat).
#* '''Exposed''' structures include HTML (structured Hypertext markup language), [http://www.ch.ic.ac.uk/svg/ SVG] (Scalable Vector graphics), TXT (un or semi-structured text)
#*Specific  '''Chemical types''' include:
#** Molecule specifications, with atom connection+co-ordinate types such as  [http://www.ch.ic.ac.uk/local/it/peni.pdb PDB], [http://www.ch.ic.ac.uk/local/it/peni.mol Molfile]
#** Spectral/analytical specifications such as [http://www.ch.ic.ac.uk/local/it/ir.dx JCAMP]
#* '''Data:''' Semantics (meaning) can be added to data structures to make it ''re-usable'' in different contexts: XML (eXtensible markup language) is the best known way of doing this.
#** Chemical Specifications include [http://cml.sf.net/ Chemical Markup Language]
#* '''MetaData:''' Data should have descriptions to add context. HTML can have exposed metadata (i.e. this document). Acrobat has structure for metadata (XMP) but this is rarely used! RDF is used in the  '''Semantic Web'''.-->

== Managing your  Location ==
All the above applies when you are connecting to your resources on campus (which by definition also includes South Kensington  Halls of residence). If you are outside this catchment area, some  IT services will not work  unless you enter the campus  ''virtually'' by switching on something called a  [http://www3.imperial.ac.uk/ict/services/personalcomputersupportandmobileservices/mobileaccessservices VPN]. These services include most  Scientific journals and the important databases.