Day 2

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Day 2

• MATH 248 SPRING 03

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What a Computer Does

• It can manipulate and organize information.
• Oh yeah like what?
• Move it
• Store it
• Retrieve it
• Perform simple mathematical and logical
  operations on it.

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What a Computer Does

• A computer must be programmed to do anything!
• A computer manipulates information based on its
  program!

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What a Computer Does

• It can input information from the outside world.
• It can output information to the outside world.
• It can make simple yes/no decisions based on the
  information it has been given

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THATS IT!!!!!
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Vocabulary

• CPU
• Central Processing Unit
• BRAINS
• Housed in microprocessor

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CPU Performs

• Simple Logic
• Arithmetic
• Compare , lt, or gt
• Jump, Skip
• Stores and Retrieves Insructions
• Stores and Retrieves Data

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Standard CPU Architecture

• 1 ALU
• arith. logic unit
• Circuits perform arith. logic
• 2 Control Unit
• Traffic Controller
• Fetches from memory decodes instructions tells
  system execute instructions
• 3 Address Registers
• Store addresses

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Basic Logic of a 4 bit ALU
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The Wired Version
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Standard CPU Architecture

• 4 Accumulator
• Register(s)
• Accumulates bits swapped in and out of the ALU.
• 5 CONH
• Registers
• Store exceptional conditions within the CPU
• 6 Shifter
• Stores, carries and rotates results

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Standard CPU Architecture

• 7 P Z
• Register(s)
• Let the ALU manipulate data at high speed.
• 8 P Counter
• Register
• Contains the address of the next instruction to
  be fetched and executed. The program counter is
  then incremented and the next processing cycle
  begins.
• 9 S Pointer
• Register
• Keeps track of the STACK.

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Standard CPU Architecture

• The Processing Cycle (simplified)
• Fetch the next instruction
• Decode instruction
• Execute instruction
• Increment counter

• 10 STACK
• Register(s)
• The Stack is not part of the CPU it is part of
  memory.
• The pull operation results in a transfer of the
  word at the top of the stack into the
  accumulator.
• The push operation puts a word on the stack. The
  final accumulator contents are deposited on top
  of the stack.
• The Stack Pointer keeps track of whats next on
  the stack. First word at the bottom.

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BASIC COMPUTER
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More Detailed CPU
Special Registers

• CU Instruction Decoder
• 3-State is a gate that can send a 1, 0, or
  terminate
•  
• Again Program Counter is a gate which can also
• A) increment by 1
• B) reset to 0

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PRIMARYMEMORY

• RAM
• Stores instructions and data of the executed
  program 64-256 Mb
• LOST!
• ROM
• Read Only Memory Important Memory400-500 Kb
• SAVED
• CPU Registers
• Special High Speed Memory Locations holds
  information while program is executed
• LOST!

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More Detailed Computer
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STORAGE

•  bit? 1 or 0
• byte?23 bits
• Kb?210 bytes 213 bits
• Mb?210Kb 220 bytes 223 bits
• Gb?210Mb 220 Kb 230 bytes 233 bits
• Tb?210Gb 220 Mb 240 bytes 243 bits

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More VOCABULARY

• WORD- of bits in a CPU register
• EX word length of 32 bits or 4 bytes
• word 010001000011100010000101010110111
• ADDRESS- is a number attached to each word or
  byte so it can be accessed
• OPCODE- basic machine operations , , load
  , store,.

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More VOCABULARY

• OPERAND-the item (word) to be operated on
•  
• MACHINE INSRUCTIONS- are words
• part 1 represent an opcode
• part 2 represent address of operand

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NOWLook at Example

• FORTRAN 90
• Page 4

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More VOCABULARY

• ASSEMBLY LANGUAGE set of abbreviated text names
  for opcodes and operands
• ASSEMBLER changes assembly language into machine
  language

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NOWLook at Example

• FORTRAN 90
• Page 4

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More VOCABULARY

• HIGH LEVEL LANGUAGE program source code written
  in a language similar to our own.
• COMPILER converts high level code into machine
  code.
• SYNTAX rules for a language . These RULES MUST
  be OBEYED!!!

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4 Steps to Programming

• 1) THE PROBLEM
• What is the GOAL?
• The Inputs ? The
  Outputs ? The Givens
  To Prove

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4 Steps to Programming

• 2) (i) DATA ORGANIZATION
• What are the Variables ?
• What are the units of Variables ?
• What symbols represent the Variables?
• (ii) ALGORITHM
• How to solve the Problem ?
• Flow Charts and Psuedocode
• Basic Outline of the proof

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4 Steps to Programming

• 3) PROGRAM CODING
• Developing Program for Algorithm
• Coding Program
• rough draft of proof
• writing proper proof

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4 Steps to Programming

• 4) EXECUTION TESTING
• Compile and Run Program
• Test Algorithm and Program with specific input
  values where the output values are already known.
  
• Hand proof to teacher/editor and Get back
  graded proof and cry.

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ERRORS

• A) Compile Time
• B) Run Time
• C) Logic

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NOWLook at Basics of a Program

• FORTRAN 90
• Section 2.5