Cmpe 150 03

1
Cmpe 150- 03

• Summer 2001

2
SOFTWARE PACKAGES

• 1960s
• mainframe nuclear physics applications
• mainframe machine control programs
• mainframe accounting applications
• 1970s
• mainframe database managers
• PC accounting applications
• PC word processing
• PC telecommunications
• PC spreadsheets
• 1980s
• PC database managers

3
SOFTWARE PACKAGES

• SOFTWARE PACKAGE TECHNOLOGY
• User friendly package
• Batch package
• Interactive package
• Menu driven
• Pull down menu
• Icons
• Tutorial disk

4
SOFTWARE PACKAGES

• OPERATING SYSTEM
• Provides an interface between the user and the
  computer
• Schedules an efficient use of the CPU and
  eliminates the need for human intervention
• Manages data and files making them available as
  needed and provides security to multiple users
• Executes other computer programs
• Manages peripheral devices such as printers, disk
  drives, and tape drives.

5
SOFTWARE PACKAGES

• MAINFRAME OPERATING SYSTEMS
• The OS for a mainframe computer must be able to
  run multiple jobs concurrently.
• In a time-sharing system, a computer gives each
  active terminal a fraction of a second of CPU
  time. During this time a portion of a program
  entered at the terminal is executed.
• In a batch mode en entire job is entered at one
  time from a disk drive. Each job is assigned a
  priority and placed in a queue to be executed.
• Multiple batch entry sites are called remote job
  entry sites.

6
SOFTWARE PACKAGES

• HOW DOES THE OS DO IT?
• Supervisor Program remains in internal memory at
  all times and manages the loading of other parts
  of the OS into the memory as needed. It also
  supervises the loading of application programs
  into the internal memory.
• Compiler is the program translator
• Buffer is a section of memory separate from the
  internal memory unit which acts as an
  intermediary storage area for input and output.
  Therefore CPU is not slowed down by the input/
  output process because of the buffer.

7
SOFTWARE PACKAGES

• PC Operating Systems
• The operating system controls the hardware
• It interprets the user s commands command
  interpreter determines what keystrokes mean and
  sends a message to the appropriate utility or
  application program to carry out the command.
• The operating system maintains a file system on
  secondary storage.
• DOS file system has a unique name for each file,
  which is supplied by the user and is used for
  future retrievals
• The list of the files on a disk is known as DISK
  DIRECTORY

8
SOFTWARE PACKAGES

• EXAMPLES OF MS-DOS COMMANDS
• COPY Copies one or more files to a new disk or
  location
• COPY ATEST BTEST
• DIR Displays a directory of the user s files
• DIR A
• FORMAT Initialises a disk
• FORMAT B