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Week 04 Notes for DAT2343
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-Ian! D. Allen - idallen@idallen.ca - www.idallen.com

Review: Answers for Assignment 2 are posted and reviewed.
Assignment 3 is assigned, due next week.

Lecture Notes for This Week

    07AlternativeBinaryRepresentations.html
    08Basic_Character_Encoding.wmv
     - Errata: end-of-line: Mac uses only CR, Unix uses only LF
    08Basic_Character_Encoding.ppt
     - Errata: end-of-line: Mac uses only CR, Unix uses only LF
    08CharacterEncoding.htm
     - EBCDIC will only be quizzed in Homework assignments, not on tests
    09ByteOrderEndian.html
    10FloatingPoint.htm
    10Summary_of_Basic_Data_Encoding.pps
     - omit EBCDIC, Zoned Decimal, Packed Decimal, and BCD
    10Summary_of_Basic_Data_Encoding.ppt
     - omit EBCDIC, Zoned Decimal, Packed Decimal, and BCD
    10big_picture.txt
    10ieee754_conversions.txt
    04bit_operations.txt (re-visit using bit masks with IEEE754 and ASCII)

Notes
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Floating Point:

    Reference URL: http://steve.hollasch.net/cgindex/coding/ieeefloat.html

    The range of IEEE754 single-precision floating-point is approximately:
      -2**127 to +2**127  -or-  -10**38  to +10**38  (approximately)

    Floating-point underflow happens for IEEE754 single-precision
      floating-point values closer to zero than approximately 2**(-127)
      which is approximately 10**(-38)

    Floating-point overflow happens for IEEE754 single-precision
      floating-point values greater than approximately 2**(127)
      which is approximately 10**(38).

    The exact values are a bit complicated to explain due to the use of
    special "denormalized" formats; see the above URL for details.

Q: How can you tell if bit pattern 0x5A5A is ASCII or a number?
A: You can't.  Bits are just bits.  Your program has to know what it put there.


Review the Class Notes file 04bit_operations.txt
  - bitwise AND, bitwise OR, biwise NOT, masking
  - word length affects bitwise NOT (why?)
  - understand Java/C language bit expressions, e.g. char x = ~0x7;
    http://www.janeg.ca/scjp/oper/unary.html

Assignments Assigned This Week

    assignment03.txt due next week in Digital Dropbox