Chapter 4 (Pt. 1)

• Binary Represenation • Boolean Logic • Gates • Circuits

Two types of information representation • External Represenation • Internal Represenation Binary represenation is a base-2 positional numbering system.

• Whenever there is a 1 in a column, add the positional value of that column to a running sum • Whenever there is a 0 in a column, add nothing • The final sum is the decimal value of this binary number.

Maximum number of binary digits that can be used to store integers: 16, 32, or 64 bits.

Operation that produces an unasigned value greater than 65,535; 16 bit system.

Octal Numbering Sytem

To covert from binary to base eight: group in threes. To convert from eight to binary: expand in threes. From ten to eight: use binary as the intermediate.

Hexadecimal Numbering System

To convert from binary to base sixteen: group in fours. To convert from base sixteen to binary: expand in fours. To convert from base ten to sixteen use binary as an intermediate.

Can be represented in binary by using signed integer techniques; assigned a specific bit(s) as indicators for decimal or cutoff. Normalize the number • First significant digit is immediately to the right of the binary point

• ±M x B±E • M is the mantissa, B is the exponent base (usually 2), and E is the exponent

Code mapping • Assigning each printable letter or symbol in our alphabet a unique number ASCII • International standard for representing textual information in the majority of computers • Uses 8 bits to represent each character.

• Encoding systems are used to assign a number for each letter or character • There are many possible encoding systems, with each one using its own assignment

• Any given computer needs to support different encodings • When data is passed between different encodings or platforms, the data runs th risk of corruption.

• An international encoding standard for use with different languages and scripts. • Each letter, digit, or symbol is assigned a unique numeric value that applies across different platforms, program and languages.

• Unicode standard has been adopted by industry leaders • Unicode enables a single software product or website to be targeted across multiple platforms, languages and countries without re-engineering. • The Unicode consortium was founded to develop, extend and promote the use of the Unicode Standard.

UTF - 8 • Variable byte representation • 1 byte to 4 bytes per code point • First 128 characters are encoded just like ASCII UTF - 16 • Variable byte representation • 2 bytes to 4 bytes per code point • Optimized for languages residing in the 2 bytes character range UTF - 32 • Fixed width byte representation • 4 bytes per code point

Characters are assigned a number written in the U+XXX form. • Called a Code Point • Example: U+0041 • The numbers are hexadecimal • Listed on the Unicode website • Hellow is represented by a list of points • U+0048 | U+0065 | U+006C | U+006F

Python 2 • Enconding is ASCII • Not all python 2 internal supports Unicode Python 3 • ”< type ‘str’ >” is a Unicode Object • All built-in modules support Unicode • Default enconding is UTF-8, not ASCII

Values for a given object are drown from a finite set.

Object can take on any value

It measures loudness • Units: Electrical Voltage

Time it takes for the wave to make on complete cycle • Units: Time (Seconds)

Total number of cycles per unit time • Units: Hertz (Hz)