Nita Arora (PGT Comp. Sc.) K.H.M.S.
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS Underlying Structure Logical Structure of Digital Computers Secondary Memory
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS Input/Output Secondary Memory
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Terminal </li></ul><ul><ul><li>Simpler than a PC </li></ul></ul><ul>...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Terminal </li></ul><ul><ul><li>Special types: </li></ul></ul><ul><ul...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Common input methods: </li></ul><ul><ul><li>Magnetic ink character r...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Common input methods: </li></ul><ul><ul><li>Light Pen  – A Light Pen...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Common input methods: </li></ul><ul><ul><li>Touch Screen  A Touch Se...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Common output methods: </li></ul><ul><ul><li>Print  – output to pape...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS Input/Output Multimedia  –  relatively new term for computer input and outpu...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS Computer Memory Secondary Memory
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Memory </li></ul><ul><ul><li>All data flows to and from memory </li>...
Types of Memory ROM RAM SRAM DRAM PROM EPROM EAPROM EAPROM
Primary Memory <ul><li>It is the main or internal memory .  </li></ul><ul><li>It can be broadly categorized into two parts...
RAM <ul><li>It is known as the  Read and Write memory .  This memory is  volatile.  </li></ul><ul><li>Whatever information...
Dynamic RAM <ul><li>Dynamic Memory is often referred to as volatile memory.  </li></ul><ul><li>Data is stored within the c...
Static RAM        <ul><li>Static memory is more  expensive  to produce than Dynamic memory, but because of its  lower powe...
ROM <ul><li>It is a memory unit that  performs the Read   operation  only and  does not have a write capability.  </li></u...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS Computer Files Secondary Memory (Secondary Storage)
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>When power is off, everything stored in memory is lost </li></ul><ul...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Sequential access files </li></ul><ul><ul><li>Usually stored on magn...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Types of DASD </li></ul><ul><ul><li>Fixed (hard) drives </li></ul></...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Types of DASD </li></ul><ul><ul><li>Removable: </li></ul></ul><ul><u...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Newer type of DASD </li></ul><ul><ul><li>Optical Disk Storage </li><...
Secondary Memory <ul><li>It is the   Permanent  memory. The information stored is permanent in nature and it uses external...
Secondary Storage Devices <ul><li>This is a floppy disk! We used it to store information and it’s main advantage is that i...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Each memory cell is a set of circuits </li></ul><ul><li>Each circuit...
Bits and Coding Schemes Figure 2.4  Computer Coding Schemes . . . . . . . . . . . . . . . . . .
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS Arithmetic/Logical Unit Secondary Memory
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Consists of VLSI circuits on a silicon chip </li></ul><ul><li>Carrie...
CPU - Registers (1 of 2) <ul><li>The CPU also contains a small high speed  memory  which is used to store temporary result...
CPU - Registers (2 of 2) <ul><li>Accumulators  - serve the purpose of holding data used in calculations. </li></ul><ul><li...
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS Control Unit Secondary Memory
B ASIC  C OMPONENTS   OF  C OMPUTER  S YSTEMS <ul><li>Controls computer to take advantage of speed and capacity of other c...
T HE  S TORED- P ROGRAM  C ONCEPT <ul><li>Program  – list of what computer needs to do for an application </li></ul><ul><l...
T HE  S TORED- P ROGRAM  C ONCEPT <ul><li>Note:   One of the primary measures of power of computers is the number of instr...
E XTENSIONS TO THE  B ASIC  M ODEL Cache Memory Cache Memory <ul><li>High-speed storage to temporarily hold data from main...
Cache memory <ul><li>Cache memory is random access memory ( RAM ) that a computer  microprocessor  can access more quickly...
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Computer Fundamentals

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Basics of computer and its operations:Functional components and their interconnection

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Computer Fundamentals

  1. 1. Nita Arora (PGT Comp. Sc.) K.H.M.S.
  2. 2. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS Underlying Structure Logical Structure of Digital Computers Secondary Memory
  3. 3. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS Input/Output Secondary Memory
  4. 4. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Terminal </li></ul><ul><ul><li>Simpler than a PC </li></ul></ul><ul><ul><li>Designed strictly for input and output </li></ul></ul><ul><ul><li>Has keyboard and screen </li></ul></ul><ul><ul><li>Does not have a processor </li></ul></ul><ul><ul><li>Connected to computer with telecommunication line </li></ul></ul><ul><ul><li>Allows user to key data directly into computer </li></ul></ul>Input/Output
  5. 5. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Terminal </li></ul><ul><ul><li>Special types: </li></ul></ul><ul><ul><ul><li>Point-of-sale (retail) </li></ul></ul></ul><ul><ul><ul><li>ATMs (banking) </li></ul></ul></ul>Input/Output
  6. 6. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Common input methods: </li></ul><ul><ul><li>Magnetic ink character recognition (MICR) – used to process bank checks </li></ul></ul><ul><ul><li>Optical character recognition (OCR) – directly scans typed, printed, or handwritten material </li></ul></ul><ul><ul><li>Imaging – inputs digital form of documents and photos </li></ul></ul><ul><ul><li>Bar code labeling – scans bar codes on packages or products, and reads into computer </li></ul></ul>Input/Output
  7. 7. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Common input methods: </li></ul><ul><ul><li>Light Pen – A Light Pen is a pointing device shaped like a pen and is connected to a VDU. The tip of the light pen contains a light-sensitive element which, when placed against the screen, detects the light from the screen enabling the computer to identify the location of the pen on the screen. </li></ul></ul>Input/Output http://doit.ort.org/course/input/275.htm
  8. 8. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Common input methods: </li></ul><ul><ul><li>Touch Screen A Touch Sensitive Screen is a pointing device that enables the user to interact with the computer by touching the screen. </li></ul></ul>Input/Output http://doit.ort.org/course/input/275.htm
  9. 9. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Common output methods: </li></ul><ul><ul><li>Print – output to paper using various types of printers </li></ul></ul><ul><ul><li>Computer output microfilm (COM) – microfilm generated for archive copies in small space </li></ul></ul><ul><ul><li>Voice response units – computer recognizes input, generates verbal response messages </li></ul></ul>Input/Output
  10. 10. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS Input/Output Multimedia – relatively new term for computer input and output in the form of text, graphics, sound, still images, animations, and/or video Of interest …
  11. 11. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS Computer Memory Secondary Memory
  12. 12. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Memory </li></ul><ul><ul><li>All data flows to and from memory </li></ul></ul><ul><ul><li>Divided into cells : </li></ul></ul><ul><ul><ul><li>Each has a unique address </li></ul></ul></ul><ul><ul><ul><li>Memory cell types: </li></ul></ul></ul><ul><ul><ul><ul><li>Byte – stores one character of data </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Word – stores two or more characters of data </li></ul></ul></ul></ul>Computer Memory
  13. 13. Types of Memory ROM RAM SRAM DRAM PROM EPROM EAPROM EAPROM
  14. 14. Primary Memory <ul><li>It is the main or internal memory . </li></ul><ul><li>It can be broadly categorized into two parts </li></ul><ul><li>RAM (Random Access Memory) </li></ul><ul><li>ROM (Read Only Memory) </li></ul>
  15. 15. RAM <ul><li>It is known as the Read and Write memory . This memory is volatile. </li></ul><ul><li>Whatever information you store is temporary in nature and when you switch off the computer everything is erased. </li></ul>
  16. 16. Dynamic RAM <ul><li>Dynamic Memory is often referred to as volatile memory. </li></ul><ul><li>Data is stored within the capacitance of a transistor. The capacitor is unable to prevent the charge from slowly discharging. This would result in the loss of data. A solution to this problem is the introduction of additional circuitry which performs a 'memory refresh' by periodically restoring the charge. </li></ul><ul><li>Dynamic memory is cheaper than Static memory and is used in larger memory systems. </li></ul>
  17. 17. Static RAM <ul><li>Static memory is more expensive to produce than Dynamic memory, but because of its lower power consumption it is often used in small to medium sized systems. </li></ul><ul><li>Static memory retains data within a cell until the data is overwritten or lost as a result of power being shut down. </li></ul>
  18. 18. ROM <ul><li>It is a memory unit that performs the Read operation only and does not have a write capability. </li></ul><ul><li>The Binary information in the ROM is made permanent during the hardware production of the unit and it is not accessible to users to store information. </li></ul>
  19. 19. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS Computer Files Secondary Memory (Secondary Storage)
  20. 20. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>When power is off, everything stored in memory is lost </li></ul><ul><li>Computer files are used to store data long term </li></ul><ul><li>File storage devices: </li></ul><ul><ul><li>Magnetic tape drives, disk drives, floppy drives </li></ul></ul><ul><ul><li>Optical CD or DVD drives </li></ul></ul>Computer Files (Secondary Storage)
  21. 21. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Sequential access files </li></ul><ul><ul><li>Usually stored on magnetic tape drives </li></ul></ul><ul><li>Direct access files </li></ul><ul><ul><li>Stored on Direct Access Storage Devices ( DASD ) - magnetic disk drives </li></ul></ul>Computer Files
  22. 22. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Types of DASD </li></ul><ul><ul><li>Fixed (hard) drives </li></ul></ul>Computer Files Figure 2.7 Diagram of a Magnetic Disk Drive
  23. 23. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Types of DASD </li></ul><ul><ul><li>Removable: </li></ul></ul><ul><ul><ul><li>Floppy drives </li></ul></ul></ul><ul><ul><ul><li>Zip drives </li></ul></ul></ul><ul><ul><ul><li>Newest: portable DASD for PCs – keychain drive </li></ul></ul></ul>Computer Files Figure 2.8 Iomega’s Mini USB Keychain Drive
  24. 24. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Newer type of DASD </li></ul><ul><ul><li>Optical Disk Storage </li></ul></ul><ul><ul><ul><li>CD-ROM 700 megabytes read-only </li></ul></ul></ul><ul><ul><ul><li>CD-R recordable </li></ul></ul></ul><ul><ul><ul><li>CD-RW rewritable </li></ul></ul></ul><ul><ul><ul><li>DVD-ROM 4.7 gigabytes read-only </li></ul></ul></ul><ul><ul><ul><li>DVD-R recordable </li></ul></ul></ul><ul><ul><ul><li>DVD-RW rewritable </li></ul></ul></ul>Computer Files
  25. 25. Secondary Memory <ul><li>It is the Permanent memory. The information stored is permanent in nature and it uses external storage devices like Floppy disk, Magnetic disk, CD-ROM etc. </li></ul>
  26. 26. Secondary Storage Devices <ul><li>This is a floppy disk! We used it to store information and it’s main advantage is that it is transportable because of its size. </li></ul>
  27. 27. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Each memory cell is a set of circuits </li></ul><ul><li>Each circuit is on or off (represented by 1 or 0) </li></ul><ul><li>Each circuit corresponds to a bit (binary digit) </li></ul><ul><li>Most computers – 8 bits (circuits) represents a character ( byte ) </li></ul><ul><li>2 common bit coding schemes used today: </li></ul><ul><ul><li>ASCII </li></ul></ul><ul><ul><li>EBCDIC </li></ul></ul>Bits and Coding Schemes
  28. 28. Bits and Coding Schemes Figure 2.4 Computer Coding Schemes . . . . . . . . . . . . . . . . . .
  29. 29. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS Arithmetic/Logical Unit Secondary Memory
  30. 30. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Consists of VLSI circuits on a silicon chip </li></ul><ul><li>Carries out: </li></ul><ul><ul><li>arithmetic – add, subtract, multiply, divide … </li></ul></ul><ul><ul><li>logical operations – comparing two numbers </li></ul></ul>Arithmetic/Logical Unit
  31. 31. CPU - Registers (1 of 2) <ul><li>The CPU also contains a small high speed memory which is used to store temporary results and control information. </li></ul><ul><li>This memory consists of a number of registers , each performing a specific function. </li></ul>
  32. 32. CPU - Registers (2 of 2) <ul><li>Accumulators - serve the purpose of holding data used in calculations. </li></ul><ul><li>Address Registers - are used for storing the memory location of data or instructions to be used by a program. </li></ul><ul><li>Stack Pointer - this register is used during sub-routine nesting and stack based arithmetic. </li></ul><ul><li>Status Register - this register provides a service to the CPU by maintaining the status of the last operation carried out by the ALU. </li></ul><ul><li>Instruction Pointer - sometimes referred to as the program counter, the pointer is responsible for retaining the memory address of the next instruction to be executed. </li></ul>
  33. 33. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS Control Unit Secondary Memory
  34. 34. B ASIC C OMPONENTS OF C OMPUTER S YSTEMS <ul><li>Controls computer to take advantage of speed and capacity of other components </li></ul><ul><li>Directed by list of operations (program) that tells control unit what to do </li></ul><ul><li>decoding the instructions within a computer </li></ul><ul><li>sequencing the reading and writing of data within the CPU and externally on the data bus </li></ul><ul><li>controlling the sequence in which instructions are executed </li></ul><ul><li>controlling the operations performed by the ALU </li></ul>Control Unit
  35. 35. T HE S TORED- P ROGRAM C ONCEPT <ul><li>Program – list of what computer needs to do for an application </li></ul><ul><li>Instruction – each individual step or operation in a program </li></ul><ul><li>Control unit – carries out one step or instruction at a time at electronic speed </li></ul>
  36. 36. T HE S TORED- P ROGRAM C ONCEPT <ul><li>Note: One of the primary measures of power of computers is the number of instructions it can execute in a given period </li></ul>MIPS – millions of instructions per second executed by the control unit MFLOPS – millions of floating point operations per second
  37. 37. E XTENSIONS TO THE B ASIC M ODEL Cache Memory Cache Memory <ul><li>High-speed storage to temporarily hold data from main memory waiting to be processed </li></ul><ul><li>Entire blocks of data moved at one time into cache </li></ul><ul><li>Enables CPU to execute much faster </li></ul><ul><li>Also incorporated into DASD controllers </li></ul>
  38. 38. Cache memory <ul><li>Cache memory is random access memory ( RAM ) that a computer microprocessor can access more quickly than it can access regular RAM. As the microprocessor processes data, it looks first in the cache memory and if it finds the data there (from a previous reading of data), it does not have to do the more time-consuming reading of data from larger memory . </li></ul><ul><li>Cache memory is sometimes described in levels of closeness and accessibility to the microprocessor. An L1 cache is on the same chip as the microprocessor. (For example, the PowerPC 601 processor has a 32 kilobyte level-1 cache built into its chip.) L2 is usually a separate static RAM (SRAM ) chip. The main RAM is usually a dynamic RAM ( DRAM ) chip. </li></ul><ul><li>Cache that is built into the CPU is faster than separate cache, running at the speed of the microprocessor itself. However, separate cache is still roughly twice as fast as Random Access Memory (RAM). Cache is more expensive than RAM, but it is well worth getting a CPU and motherboard with built-in cache in order to maximize system performance. </li></ul>
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