Department of Computer and Information Science, School of Science, IUPUI

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Department of Computer and Information
Science,School of Science, IUPUI
CSCI 230
Computer Architecture
Dale Roberts, Lecturer Computer Science,
IUPUI E-mail droberts_at_cs.iupui.edu
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What is a Computer?

• Computer
• Device capable of performing computations and
  making logical decisions
• Computers process data under the control of sets
  of instructions called computer programs
• Personal computers economical enough for
  individual
• Distributed computing computing distributed over
  networks
• Client/server computing sharing of information
  across computer networks between file servers and
  clients (personal computers)

Dale Roberts
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What is a Computer? (cont.)

• Computer Hardware
• Various devices comprising a computer
• Keyboard, screen, mouse, disks, memory, CD-ROM,
  and processing units
• Hardware Trends every year or two the following
  approximately double (Moores Law)
• Amount of memory in which to execute programs
• Amount of secondary storage (such as disk
  storage)
• Used to hold programs and data over the longer
  term
• Processor speeds
• The speeds at which computers execute their
  programs

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What is a Computer? (cont.)

• Computer Software
• Computer Programs that run on a computer,
  including
• Operation System (OS)
• Application Software
• Computer Language

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Moore's Law

• Defined by Dr. Gordon Moore during the sixties.
• Predicts an exponential increase in component
  density over time, with a doubling time of 18
  months.
• Applicable to microprocessors, DRAMs , DSPs and
  other microelectronics.
• Monotonic increase in density observed since the
  1960s.

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Moores Law - Density
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Moore's Law and Performance

• The performance of computers is determined by
  architecture and clock speed.
• Clock speed doubles over a 3 year period due to
  the scaling laws on chip.
• Processors using identical or similar
  architectures gain performance directly as a
  function of Moore's Law.
• Improvements in internal architecture can yield
  better gains than predicted by Moore's Law.

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Moores Law - Clock Speed
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What is a Computer? (cont.)

• Internet
• The Internet enables
• Quick and easy communication via e-mail
• International networking of computers
• Packet switching
• The transfer of digital data via small packets
• Allows multiple users to send and receive data
  simultaneously
• No centralized control
• If one part of the Internet fails, other parts
  can still operate
• Bandwidth
• Information carrying capacity of communications
  lines
• Ex Internet T2 at IUPUI
• World Wide Web
• Locate and view multimedia-based documents on
  almost any subject
• Makes information instantly and conveniently
  accessible worldwide
• Possible for individuals and small businesses to
  get worldwide exposure
• Changing the way business is done

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Computer Organization

• A Typical Von-Neumann Architecture
• Example
• Input unit
• Output unit
• Memory unit
• Arithmetic and logic unit (ALU)
• Central processing unit (CPU)
• Secondary storage unit

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Computer Organization (cont.)

• Six logical units in every computer
• Input unit
• Obtains information from input devices (keyboard,
  mouse)
• Output unit
• Outputs information (to screen, to printer, to
  control other devices)
• Memory unit
• Rapid access, low capacity, stores input
  information
• ROM (Read Only Memory) CMOS, EPROM
• RAM (Random Access Memory) SRAM, DRAM, SIMM,
  DIMM

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Computer Organization (cont.)

• Six logical units in every computer (cont)
• Arithmetic and logic unit (ALU) part of CPU
• Performs arithmetic calculations (addition,
  subtraction...) and logic decisions
• Control unit (CU) - part of CPU
• Supervises and coordinates the other sections of
  the computer
• Secondary storage unit
• Cheap, long-term, high-capacity storage
• Stores inactive programs

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Computer Organization (cont.)

• Central Processing Unit (CPU),
• brain of a computer, consisting of
• Arithmetic and logic unit (ALU) performs
  arithmetic calculations (addition,
  subtraction...) and logic decisions (gt, lt, ,
  ...)
• Control Unit (CU) decodes each machine
  instruction and sends signal to other components
  for carrying out the instruction.
• An integrated circuit (IC) that is a full central
  processing unit is called a microprocessor (?p)
  a CPUs current instruction and data values are
  stored temporally inside the CPU in special
  high-speed memory location called registers.
• CPU speed ? MHz (M Mega 106, Hz1/sec)

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Computer Organization (cont.)

• Memory
• A large collection of circuits, each capable of
  storing bit
• Cells (words) manageable units typical size is
  8 bits (1 byte), some machines are 16 bits (2
  bytes) and some are 32 bits or 64 bits
• Byte (8 bits), KB (kilobyte, 103 ? 210 bytes), MB
  (Megabyte, 106 ? 220 bytes), GB (Gigabyte, 109 ?
  230 bytes). Note k ? K because 1000 ? 1024.

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Computer Organization (cont.)

• Computer memory is comparable to a collection of
  numbered mailboxes. To identify individual cells
  in a machines main memory, each cell is assigned
  a unique name, called its address
• The organization of byte-size memory cell

H
e
l
l
o
,
ASCII
...
...
Data
01001000
01100101
01101100
01101111
01101100
00101110
Address
0000 0101
0000 0110
0000 0111
0000 1000
0001 0001
0001 0010
Address Bus
Data Bus
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Operation System (OS)

• Responsibilities
• Communicating with the computer user
• Managing allocation of memory, of processor
• time, and of other resources for various tasks
• I/O handling BIOS vs DOS services (Interrupts)
• Read/Write data from secondary storage
• Evolution of Operating Systems
• Batch processing do only one job or task at a
  time
• Operating systems manage transitions between
  jobs and Increase throughput (amount of work
  computers process)
• Multiprogramming Computer resources are shared
  by many jobs or tasks
• Timesharing Technique used to implement
  multiprogramming where the computer runs a small
  portion of one users job then moves on to
  service the next user

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Application Software

• Developed to assist a computer user in
  accomplishing special tasks
• ex word processing applications MS-word or
  Word-perfect
• ex Spreadsheet applications Lotus1-2-3, Excel
• ex Database Oracle, MS-Access
• Software Development Life Cycle (SDLC)
• Problem specify the problem requirements
• Analysis analyze the problem
• Design design the algorithm to solve the problem
• Implementation Implement the algorithm
• Testing test and verify the completed program
• Maintenance maintain and update the program

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Programming Languages

• Machine languages (machine dependent)
• Native tongue of a particular kind of computer.
  Each instruction is a binary string. The code is
  used to indicate the operations to be performed
  and the memory cells to be addressed. This form
  is easiest form of computers to understand, but
  is most difficult for a person to understand.
• Strings of numbers giving machine specific
  instructions
• Example 1300042774
• 1400593419
• 1200274027

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Programming Languages (cont.)

• Assembly languages (machine dependent)
• English-like abbreviations representing
  elementary computer operations (translated via
  assemblers)
• Again specific to only one type of computer. Uses
  descriptive names for operations and data, e.g. ,
  LOAD value, ADD delta, STORE value.
  Assemblers will translate these to machine
  languages. Intermediate level. Somewhat
  descriptive, but basically following the machine
  instructions.
• Example LOAD BASEPAY
• ADD OVERPAY
• STORE GROSSPAY

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Programming Languages (cont.)

• High-level languages (machine independent)
• Codes similar to everyday English
• High-level languages Write program instructions
  called statement that resemble a limited version
  of English. e.g., the statement value value
  delta. Portable, meaning it can be used on
  different types of computers without
  modifications. Compilers translate them to
  machine languages. Examples are FORTRAN, PASCAL,
  COBOL, C, C, BASIC etc.
• Use mathematical notations (translated via
  compilers)
• Example
• grossPay basePay overTimePay
• Example
• Statement a a b

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Programming Languages (cont.)

• Structured programming
• Disciplined approach to writing programs
• Clear, easy to test and debug and easy to modify
• Multitasking
• Specifying that many
• activities run in parallel (still timesliced)

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Semantic Gap

• A semantic gap exists between the amount of
  information conveyed in assembly language v high
  level languages. Consider the following C single
  statement x x 3
• This single statement may require many assembly
  language statements (operations) Load memory
  location 24 into accumulator Add a constant 3
  to the accumulator Store accumulator in
  memory location 24
• The number of executable statement expands
  greatly during the translation process from a
  high level language into assembly language.

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C Programming Language

• C
• High-level general-purpose language developed in
  1972 at ATT Bell Lab. By Dennis Ritchie from two
  previous programming BCPL and B
• Originally developed to write the UNIX operating
  system
• Hardware independent (portable)
• By late 1970's C had evolved to "Traditional C"
• Today, virtually all new operating systems are
  written in C or C.
• The current standard in C is ANSI C.
• C is a more advanced version of C,
  incorporating among other things, the
  object-oriented constructs
• Standardization
• Many slight variations of C existed, and were
  incompatible
• Committee formed to create a "unambiguous,
  machine-independent" definition
• Standard created in 1989, updated in 1999
• C has become a popular language industry due its
  power and flexibility

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The C Standard Library

• C programs consist of pieces/modules called
  functions
• A programmer can create his own functions
• Advantage the programmer knows exactly how it
  works
• Disadvantage time consuming
• Programmers will often use the C library
  functions
• Use these as building blocks
• Avoid re-inventing the wheel
• If a pre-made function exists, generally best to
  use it rather than write your own
• Library functions carefully written, efficient,
  and portable

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The C Standard Library (cont.)

• The Key Software Trend Objects in C and JAVA
• Reusable software components that model items in
  the real world
• Meaningful software units ex Date objects, time
  objects, audio objects, video objects, file
  objects, record objectsany noun can be
  represented as an object
• More understandable, better organized, and easier
  to maintain than procedural programming
• Favor modularity

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The C Standard Library

• include ltstdio.hgt
• main()
• int i
• for (i 0 i i lt 10)
• printf ("Hello World!\n")

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A Typical C Program Development Environment

• 1. Edit
• 2. Preprocess
• 3. Compile
• 4. Link
• 5. Load
• 6. Execute

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A Typical C Program Development Environment
(cont.)

• Procedure to Prepare a C Program for Execution

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Constructs in C Language

• Type Declarations ex int, float,
• I/O ex printf(), scanf()
• Arithmetic and Logical Operations ex
  ,-,,/,,gt,lt,,
• Arrays, Pointers, Structures, Unions,
• Functions
• Arguments return values
• Recursion
• Control Mechanisms ex if, else, while, for,
• Characters Strings ex strcat(), strcpy(),
• File Processing ex fopen(), fclose(),
• Pre-processor ex define
• Misc.
• bit operations, ...

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Acknowledgements

• Moores Law Kopp, Carlo. Monash University.
  Melbourne, Australia. 2000.