CIS (Chapter 7)

Binary number system

Computers use base-2 to represent numbers; limited to only use 0 and 1; 0, 1, 10, 11, 100, 101, 110, 111, 1000, ...

Bit

Contraction for "binary digit"; can be interpreted as numbers; groups of it form symbols; Memory is arranged inside a computer in a very long sequence of bits; The physical phenomenon can be encoded, the information can be set and detected to present or absent

Decimal number system

Example, 1010 (base 10) is written as (0x1)+(1x10)+(0x100)+(1x1000)= 1010

16 (because 2^4=16)

How many symbols can be represented by four bits?

Metadata

Information describing information; is the third basic form of data; does not require its own binary encoding; separate from the information that is describes;

2^k

K bits in a sequences yield how many symbols

Discrete

Means "distinct" or "separable"; It is not possible to transform one value into another by tiny gradation; There are no "shades of gray"

Collating sequence

Placing information in order by using non-digit symbols; need to agree on an ordering for the basic symbols; defines how characters relate to each other when they are compared

Parity

Refers to whether a number is even or odd; An extra bit is added to the memory to help detect errors; A ninth bit per but can detect errors using partly; count the number of 1's in the byte, if there is an even number of 1's we set the ninth bit to 0

Digitize

Represent information with digits; means the ten Arabic numerals 0 through 9; in computing, it can use any symbol; have short names; representing information by symbols

Binary vs decimal

SBinary value (Base 2): 1, 2, 4, 8, ... Decimal value (Base 10): 1, 10, 100, 1000.. Example: 1010 in binary: (1x8)+(0+4)+(1x2)+(0x1) in decimal: (0x1)+(1x10)+(0x100)+(1x1000) Example: 110101 (1x1)+(0x10)+(1x100)+(0x1,000)+(1x10,000)+(1x100,000)=110101 (1x32)+(1x16)+(0x8)+(1x4)+(0x2)+(1x1)=53

Hex

Short for hexadecimal digits, are base-16 numbers; Uses decimal numbers, and then the first six latin letters 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F Binary can be converted into Hex

Structure tags

Software can use a simple algorithm to find what is needed; helped digitize Oxford English Dictionary

ASCII

Stands for American Standard Code for Information Interchange; A widely used 7-bit (2^7) code to produce 128 symbols, needed for the 95 different characters needed for English characters; IBM extends it to 8-bit symbols (2^7) (called byte) to produce 256 symbols, to include texts from other languages, and its a standard unit for computer memory.

PandA

The name used for two fundamental patterns of digital information; + Presence + Absence The phenomenon is either present or not that van be viewed as "true" or "false"; The unit is a specific place (in spaces and time), where the presence or absence of the phenomenon can be set and detected; Two earliest uses uses of it were to... + Encode numbers + Encode keyboard characters; Part of binary system

Bar codes

Use more than the minimum number of bits to encode information In the UPC-A encoding, 7 bits are used to encode the digits 0 - 9; Encodes the manufacturer (left side) and the product (right side); The bit patterns were chosen to appear as different as possible from each other; Different encodings for each side make it possible to recognize whether the code is right side up or upside down

Bumps or pits

________ encode information on DVDs and CDs