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Our Lady of the Rosary College 2006-2007 S.2 Computer Literacy. Lesson 8 Storage Unit Mr. Ku Heung Chin. 0100 0001. A. 0100 0101. E. 0100 0010. B. 0100 0110. F. 0100 0011. C. 0100 0111. G. 0100 0100. D. 0100 1000. H. The unit of memory.
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Our Lady of the Rosary College2006-2007 S.2 Computer Literacy Lesson 8 Storage Unit Mr. Ku Heung Chin
0100 0001 A 0100 0101 E 0100 0010 B 0100 0110 F 0100 0011 C 0100 0111 G 0100 0100 D 0100 1000 H The unit of memory • How does computer store the character ‘A’? • Computer can only ‘read’ binary digit (0 or 1). • Computer will change a character into 8 binary digit, • e.g. A:0100 0001 • The coding standard is ASCII.
Bits and Bytes • Each binary digit is 1 bit • How many bits in one character? • Ans: 8 bits • Each character need 1 Byte of memory. • How many bits in 1 Byte? • Ans: 8 bits
Main Memory • It stores data and instruction to be executed by the CPU. • Random Access Memory (RAM) • Read Only Memory (ROM)
Secondary storage • Magnetic storage devices • Floppy disk drive • Hard disk • Optical storage devices • CD-ROM • CD-RW • DVD-ROM • DVD-RW
Floppy Disk Drive • Small capacity.(1.2MB / 1.44MB) • Read/write speed is very slow.
Hard Disk • High capacity (80 GB ~ 500 GB) • Fastest processing speed. • http://www.youtube.com/watch?v=9eMWG3fwiEU&eurl
CD-ROM / CD-RW • Compact Disc Read-Only Memory. • 650 MB ~ 800MB • Can write only once • Compact Disc Re-Writable • can re-write data for many times
DVD / DVD-RW • Digital Versatile Disc / Digital Video Disc • 4.7GB – 8.5GB
Other Storage Devices • Memory Cards • Smart Media (SM) • Compact Flash (CF) • Secure Digital Card (SD) • Memory Stick (MS) • xD-Picture Card (XD)
The End Thanks for coming!!