Download Data Representation and Memory Storage: How Computers Store and Access Information and more Study notes Music in PDF only on Docsity! Data Representation and Memory Storage Data Representation • How does a computer represent a song? A picture? A video? • Bits – 0’s and 1’s • So how does a computer represent bits? How to add two numbers in Binary? Data Representation • ASCII (American Standard Code for Information Interchange) is the most widely used coding scheme to represent data Data Representation
Symbol] Decimal] Binary Symbol Decimal] Binary
6s__| o1o00001 a 97__| 01100001
66 01000010 b 98 01100010
67 __| o1o00011 99 | o1100011
68 __| 01000100 190 _| 01100100
69 | o1o00101 toi | 01100101
70 __ | 01000110 192 | 1100110
71 01000111 103 01100111
72 | a1o01000 104 | 01101000
73 | 1001001 i 19s | 01101001
74 01001010 106 01101010
7s__ | o1o01011 107__| 01101011
76 01001100 | 108 01101100
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nf<fxfsl<lelalm|sfolsjof2jzl{Ffalel-|zla}+|mlololo
77 | otooti01 m 109 | 01101101
78__| o1001110 n 110 | 01101110
73 01001111 o 111 | 01101111
80 01010000 Bp 112 | 01110000
Bl 01010001 q 113 | 01110001
82 | 01010010 r 114 | 01110010
83 01010011 5 115 | 01110011
a4 | 01010100 t 116 | 01110100
85 01010101 u 117 | 01110101
a6 | 01010110 v 118 | 01110110
a7 | 01010111 w 119 | 01110111
ge__| 01011000 x 120 | 01111000
ag 01011001 y 121 | 01111001
30 01011010 Zz 122 | 01111010
Memory Column1 Approximate Number of Bytes Text Pages Kilobyte 1,000 ½ page Megabyte 1,000,000 500 Gigabyte 1,000,000,000 500,000 Terabyte 1,000,000,000,000 500,000,000 Petabyte 1,000,000,000,000,000 Exabyte 1,000,000,000,000,000,000 Zettabyte 1,000,000,000,000,000,000,000 Yotabyte 1E+21,000 Memory • Two types of memory – Volatile: Program and data when being processed. Data is lost when power is turned off. – Non-Volatile: Hold configuration information, basic startup instructions. Keeps data even without power. Storage Capability • Capacity - The amount of data, in bytes, the storage can hold • Access Time - The amount of time it takes a storage device to locate an item on a storage medium • Transfer Rate - The time required to deliver an item to or from storage to the processor. Hard Disk Drives • Circuit board controls the movement of the head • Small motor spins the platters • Head determines the location of the data (read or write) • Head motor moves head to position head over data Hard Disk Drive • A head crash occurs when a read/write head touches the surface of a platter Hard Disk Drive RAM – Random Access Memory • Volatile • Many times faster than Hard Disk Cache • Used by the CPU to reduce average time to access memory. • Smaller and faster than RAM Storage Capability Capacity < Access Rate > Transfer Speed> Type General Usage Cache Memory Items waiting for use by processor RAM Items waiting for use by processor Flash Memory System configuration information Photos, tunes, … Solid State Drive Operating system, application software, data Hard Disk Drive Operating system, application software, data Optical Disk Movies, music, software to be installed Tape Backup copies of data Capacity > Access Rate < Transfer Speed< Cloud Storage • Networked online storage • Data centers *Amazon, 2 Years ago • Data is distributed it is stored at more locations Cloud Storage • Not cost efficient for the average computer user • More security risks • Download and upload rates • Companies can go bankrupt or be shut down Optical Disks and Drives • A disk drive that uses laser light or electromagnetic waves within or near the visible light spectrum as part of the process of reading or writing data to or from optical disks • Photodiodes detects the light reflection
