Data Representation and Memory Storage - CS Communityspp2k/1150/002/L05.pdf · Data Representation...
Transcript of Data Representation and Memory Storage - CS Communityspp2k/1150/002/L05.pdf · Data Representation...
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?
Data Representation
• A byte is 8 bits
• A byte represents many things in a computer such as characters, commands, colors, etc.
• All computer instructions are done by doing arithmetic operations on bytes
Data Representation
• ASCII (American Standard Code for Information Interchange) is the most widely used coding scheme to represent data
64 Bit OS vs. a 32 Bit OS
• Refers to the size of registers used by your CPU
• Supports more RAM
• More efficient
Memory
• Memory consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processing the data
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
• Contains one or more inflexible, circular platters that use magnetic particles to store data, instructions, and information
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
Flash Memory
• Non-Volatile
• Electronically erased and reprogrammed
• Stores information in cells that contain 1 bit
• Lower latency, faster, less noisy, less power consumed, more reliable than hard drives
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