1 System Software “Background software”, manages the computer’s internal resources.
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1 System Software “Background software”, manages the computer’s internal resources
2 System Software Operating system –Interface between application software (and user) and the computer –Runs programs –Processes data –Stores information –Frees the user from complicated, technical tasks
3 Examples of Microcomputer Operating System Software DOS - original standard for IBM compatibles Windows - a graphical operating environment Windows 95, Windows 98
4 Examples of Microcomputer Operating System Software Windows NT - for powerful workstations & networks OS/2 - competitor to Windows 95 Macintosh Operating System Unix - originally for minicomputers, now used on microcomputers and Internet servers
10 Input Devices Translate data from form that humans understand to one that the computer can work with Most common are keyboard and mouse Selector Buttons
11 The System Unit Electronic circuitry within the computer cabinet
12 The System Unit Two general parts Central Processing Unit (CPU) - an integrated micro- circuit that translates data into information
13 The CPU consists of : uControl Unit (CU) uArithmetic and Logical Unit (ALU) uSome Registers.
14 The Control Unit (CU) within a CPU coordinates all activities of the computer by determining which operations to perform and in what order to carry them out. The CU transmits coordinating control signals to other computer components.
15 The ALU consists of electronic circuitry to perform arithmetic operations (addition, subtraction, multiplication and division), logical operations (and, or, not, …) and to make some comparisons (less-than, equal, … etc.)
16 The System Unit Two general parts Memory - referred to as primary storage or random access memory (RAM), it temporarily holds data and programs for use during processing ( volatile )
17 RAM RAM consists of locations or cells. Each cell has a unique address which distinguishes it from other cells.
18 ROM: Read Only Memory ROM is part of memory. nProgrammed at manufacturing time nIts contents cannot be changed by users nIt is a permanent store
19 Secondary Storage Stores data and programs permanently: its retained after the power is turned off Located outside the CPU, but most often contained in the system cabinet
21 Common Secondary Media Diskettes –Data represented as magnetic spots on removable flexible plastic disks –Most common size is 3 1/2 inches, in a rigid plastic case –Disk drive holds the diskette, reads or retrieves the data and writes or stores data
22 Common Secondary Media Hard drive –Data is represented magnetically as with diskettes –Normally more than one rigid platter in a sealed unit –These disks are not removable –Significantly more capacity and faster operating than diskettes
23 Output Devices Pieces of equipment that translate the processed information from the CPU into a form that humans can understand.
25 Communications Devices Hardware that sends and receives data and programs from one computer or secondary storage device to another.
26 Units of Measurements Bit (Binary Digit)(takes two values: 1 or 0) Byte = 8 bits KB (Kilo-byte) = 1024 bytes MB (mega-byte) = 1024 KB GB (giga-byte) = 1024 MB TB (Tera-byte) = 1024 GB
27 Data Data are details of various types of transactions and details relating to specific situations, which are input to a data processing system (e.g. computer) for processing in a prescribed way. Examples of data relating to students are student- number, student-name and grades.
28 Data Document files Worksheet files Database files
29 Information Information: the result of processing data. n Information: uMust serve a useful purpose uMust be of an acceptable level of accuracy uMust be available at the right time uMust be relevant to the enterprise, person, … etc.
Knowledge Putting a number of information with the same type or same topic would be a knowledge.
31 Connectivity The computer’s capability to send and receive information from other locations.
32 Systems of interconnected computers, known as networks, are the sources of distant information. Connectivity
33 Systems of interconnected computers, known as networks, are the sources of distant information. The National Information Infrastructure (NII) is currently the Internet. Connectivity
34 Computer Viruses A computer virus is an application program designed and written to destroy other programs. - It has the ability to: uLink itself to other programs uCopy itself (it looks as if it repeats itself)
35 Examples of Viruses n Monkes nABC nCrabs nCIH
36 How do you know if you have a virus? Lack of storage capability Decrease in the speed of executing programs Unexpected error messages Halting the system
Protection against Computer Viruses Buy original copies of software only Make backups of your files Do not let any body to insert a diskette in your computer unless you are sure they do not have any viruses. Write-protect your disks Use anti-virus programs