Digital Information  digits are symbols chapter 8 BITS & THE “WHY” OF BYTES

Slide 8-2 Digitizing Information: Symbols Binary:0, 1 Decimal: 0, 1, 2,.., 8, 9 Hexadecimal: 0, 1,.., 9, A, B, C, D, E, F Dice: Coins: Sidewalks:

Slide 8-3 The FUNDAMENTAL Representation of Information The Binary World (1and0) joins the Logical World (TandF) & Physical World (PandA)

Slide 8-4 The FUNDAMENTAL Representation of Information (p. 212) By associating True with Presence & False with Absence, we can use the physical world to implement the logical world. Physical World (PandA): solid/space; light/dark; on/off...

Slide 8-5 THE FUNDAMENTAL REPRESENTATION OF INFORMATION The PandA Representation On_and_Off  Binary: two states  two symbols  Atom of Information: Irreducible (eg) Bits in Optical Discs — pits and lands (eg) Bits in Magnetic Media — North_and_South polarity

Slide 8-6 THE FUNDAMENTAL REPRESENTATION OF INFORMATION (eg) Bits in Old North ChurchOld North Church — One_and_Two (eg) Bits in Computer Memory  electronic  transistors, integrated circuits  device leveldevice level

Slide 8-7 Digital Information: Dice Symbols Base-6: Six “digits”, Six Symbols {1, 2,.., 5, 6} n dice => 6 n different combinations

Slide 8-8 Figure 8.2. n = 2  6 2 patterns/combinations

Slide 8-9 Figure 8.3. Initial assignment of letters to the dice-pair symbols.

Slide 8-10 Figure 8.4. Two complete dice- pair representations. (Note: b indicates a space.)

Slide 8-11 Extended Dice Code: Escape Box Cars: Escape from the Basic Repr. Escape A = 0

Slide 8-12 Extended Dice Code: Escape Reserving one symbol as an escape char  35 basic patterns  + 35 two-symbol patterns  esc sequences: 4 dice

Slide 8-13 Bit Sequences / Bit Patterns > Table 8.2: the number of patterns given the length of the sequence Table 8.2 > Generalizing: base ^ pattern_length = number of patterns  size of alphabet

Slide 8-14 HEX EXPLAINED > The 16 Hex Digits: 0.. 9, A.. F > Hex explained: Table 8.3, p. 217Table 8.3 > Changing Hex Digits to Bits and Back Again

Slide 8-15 Figure 8.5. Magnetic media (hard disk, tape, etc.) pluses (red) indicate magnetism of positive polarity, interpreted as “present” and minuses (blue)

Slide 8-16 Figure 8.6. Sidewalk sections as a bit pattern:

Slide 8-17 Slot Machine Symbols Each roller has five symbols, hearts, diamonds, spades, horseshoes, and three liberty bells for jackpot. 3 rollers, 5 symbols  ?number of patterns?

Slide 8-18 Binary Numerals: Ancient Gottfried Leibniz (1703): * Discovered calculus independently of Newton, and his notation is the one in general use since. * Also discovered & organized the modern binary number system binary number system * first major European intellect to take a close interest in Chinese civilization

Slide 8-19 Binary Numerals: Leibniz 64 hexagrams analogous to 6- bit binary numerals, comprise the ancient Chinese classic text called the I ChinghexagramsI Ching Leibniz noted with fascination how the I Ching hexagrams correspond to the binary numbers from 0 to

Slide 8-20 DIGITIZING TEXT Extended ASCII: An 8-bit Code  2 8 characters max (eg) ASCII Encoding of Phone Numbers x3487

Slide 8-21 Fig 8.7 ASCII, American Standard Code for Information Interchange

Slide 8-22 THE OXFORD ENGLISH DICTIONARY Structure Tags == markup language -- candidate for an XML application (like XHTML)  OEDML Figure 8.8. The OED entry for the word byte, together with the representation of the entry in its digitized form with tags.

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