Chapter 1 Data Storage(1) Yonsei University 1 st Semester, 2015 Sanghyun Park

Outline  Bits and their storage  Main memory  Mass storage(next file)  Representing information as bit patterns(next file)  Binary system(next file)  Storing integers(next file)  Storing fractions(next file)

Bits and Their Storage  Today’s computers represent information as patterns of ____  A bit (binary digit) is either one of two _____ – 0 and 1  Storing a bit within a machine requires a device that can be in one of two ______, such as a switch (on or off) or a relay (open or closed)

Bit Operations

Gates (1/3)  We think of the digit 0 as representing the value _____ and the digit 1 representing the value ____  Operations that manipulate true/false values are called ________ operations  A device that produces the output of a Boolean operation is called a ____

Gates (2/3)  Gates can be constructed from a variety of technologies such as gears, relays and optic devices  Current technology implements gates as small electronic _______  Gates are building ______ from which computers are constructed

Gates (3/3)

Flip-Flop  Circuit (set of connected _____) whose output will flip or flop between ___ values under control of external stimuli  Flip-flop can be used to store value of a ___

Flip-Flop Output  If both inputs are 0, output will ___ ______  Placing 1 on _____ input forces output to be 1  Placing 1 on _____ input forces output to be 0

Setting the Output to 1 (1/3)

Setting the Output to 1 (2/3)

Setting the Output to 1 (3/3)

Another Way of Constructing Flip-Flop

Hexadecimal Notation  Long bit streams are difficult to make sense of  The lengths of most bit streams used in a machine are multiples of _____  ____________ notation is a shorthand notation for streams of bits  Hexadecimal notation is more ________, and _____ ___________ to manually read, copy, or write

Hexadecimal Coding System

Main Memory: Cells  Cells are manageable units (typically _ bits) into which a computer’s main memory is arranged  A _____ is a string of 8 bits  The left end of the conceptual row in which the contents of a cell are laid out is called the ________ end  The right end of the conceptual row in which the contents of a cell are laid out is called the _______ end  The bit at the low-order end is called the ___ significant bit

Byte-Size Memory Cell

Main Memory Addresses  An _______ is a “name” to uniquely identify one cell in the computer’s main memory  Addresses are __________ numbers, usually starting at ____  Cells have an _____: “previous cell” and “next cell” have reasonable meanings  Memory where any cell can be accessed independently is called _______ access memory

Memory Cells Arranged By Address

Measuring Memory Capacity  “_____” normally means 1,000; Kilobyte = 2 10 = 1,024  “_____” normally means 1,000,000; Megabyte = 2 20 = 1,048,576  “_____” normally means 1,000,000,000; Gigabyte = 2 30 = 1,073,741,824