Chapter 1 Data Storage1 Yonsei University 1 st

Chapter 1 Data Storage(1) Yonsei University 1 st Semester, 2011 Sanghyun Park

Outline ± ± ± ± Bits and their storage Main memory Mass storage Representing information as bit patterns Binary system Storing integers Storing fractions (next file) (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 = 210 = 1, 024 ± “_____” normally means 1, 000; Megabyte = 220 = 1, 048, 576 ± “_____” normally means 1, 000, 000; Gigabyte = 230 = 1, 073, 741, 824