Computer Software: Telling the Machine What To Do

• A computer becomes useful only when software enters.
• Software is a series of step-by-step instructions that directs the computer turn data into information.
• Software can be categorized as systems software or applications software.
• System Software manage computer's resources which are CPU, memory, disk drives, and printers.
• DOS (Disk Operating System)
• Windows
• Applications Software is applied to a real world task.

It can be used to solve a particular problem or to perform a particular task.
• Word Processing:  Word, WordPerfect,...etc.
• Electronic Spreadsheet:  Excel, Lotus 123
• Database Management: MicroSoft Access
• Graphics
• Communication
• User friendly:  the software is easy for a novice to use or, at the least, that it can be used with a minimum amount of training.
• Programmers and End-Users:

Programmers - people who write software - must convey the logic of a program to computer in the form it can understand.
End-Users(or Users) - people who use computer software programs.
• Icons - a picture on screen and when you click on it, it will access a command and do some jobs for you.
• Creating folders and files to make everything organize under tree structures.

• Open a file -  Copy contents of the file from secondary storage to memory.     Purpose: To help CPU keep the file and CPU can modify it.
• Save or Save As - Copy the material from memory to secondary storage.   Purpose: To keep the work for a long time period because memory is volatile.
• If you have two different file names, CPU will put them in different locations of storage.  However, if you use the same file name for two different materials, then the latter material will overwrite the previous material.
• Save a file - Most of software use "SAVE" to overwrite previous material.
• Save As - The command "SAVE AS" will let user have a chance to choose a new file name or stay in the old file name.

   That is,
                If you change a file name, then you will have both files.
                If you stay the same file name, the old material will be gone.

• You will store a lot of files in your disk.  If you know how to organize them, you will have a easy time to look for a file.
• The file organization is based on a tree structure of folders.
• For example,

                                            A:                                                (Your floppy disk drive)
                                          /     \
                              Cosi 118     ENGL 111                             (Two folders)
                               /    |     \              /          \
                      Words  Web  SP       Notes   HW                     (Sub folders)
                      /   |     \
               hw1   hw2  hw3                                                        (Files)
• You need to know
• How to create a folder.
• How to create a sub folder
• How to copy a folder or a file to a new place.     (BACKUP)
• How to move a folder or a file to another storage.

Operating Systems:  Hidden Software

• An operating system is a set of programs that lies between applications software and the computer hardware; it is the fundamental software that controls access to all other software and hardware resources.
• The most important program in the operating system, the program that manages the operating system, is the supervisor program, most of which remains in memory and is thus referred to as resident.  The supervisor controls the entire operating system and loads into memory other operating system program (called nonresident) from disk storage only as needed.
• The process of loading the operating system into memory is called bootstrapping, or booting the system.
• An operating system has three main functions:
1. manage the computer's resources, such as
• central processing unit
• memory
• disk drives
• printers
2. establish a user interface
3. execute and provide services for applications software.
• In multiprogramming, two or more programs can be executed concurrently.
• The process of allocating main memory to programs and keeping the programs in memory separate from one another is called memory management.
• The technique whereby part of the program is stored on disk and is brought into memory for execution as needed is called virtual storage.
• The memory area (divided into foreground and background) for programs with highest priority is the foreground.
• Examples of Operating Systems for Personal Computers
• Windows 95
• Windows 98
• Windows NT  -  stronger security features
• Windows 2000
• Windows XP