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Hardware vs. Software Great Example: Data Compression

Hardware vs. Software Great Example: Data Compression. This lecture has a theme: Hardware/Devices are getting bigger, meaner, and faster, but Sometimes clever software can make even more of a difference.

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Hardware vs. Software Great Example: Data Compression

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  1. Hardware vs. SoftwareGreat Example: Data Compression • This lecture has a theme: • Hardware/Devices are getting bigger, meaner, and faster, but • Sometimes clever software can make even more of a difference. • Designing clever software is often much more cost effective and turn around time is faster. • We’ll look at one clever piece of software that beat the hardware

  2. Storage Units • One character is represented using 8 bitsExample: ‘A’ = 1010 0001 • 8 bits = 1 byte • Kilobyte (KB) 1,000 bytes • Megabyte (MB) 1,000,000 bytes • Gigabyte (GB) 1,000,000,000 bytes • Terabyte (TB) 1,000,000,000,000 bytes (trillion) • Message: Just know the differences in magnitude

  3. Storage Unit (Examples) • A high resolution image file (jpg format) is 500 KB • The highest quality images can be as large as 10 MB • Your average 100 page word document would take up about 2 or 3 MB • My 143 page Ph.D thesis takes up 6.4 MB (includes embedded pictures) • Walmart’s central database is approximately 2 TB (terabytes) or so they say… • Message: Just be aware of the striking difference between 2TB and 500KB. One is insignificant compared to the other

  4. Storage Unit (Examples) • A 4 minute song (mp3 format) is about 5 MB • In an uncompressed format (wav), it would be about 60 MB (4 minute song) • Message: Quality is the same. They seem close in size, but imagine waiting 5 minutes vs. 1 hour to download. • CD quality songs 50 minutes (600MB). • A 22 minute “South Park” video (mpg format) is 40 MB (very poor quality) • A higher quality video (mpg format) can take up as much as 10 MB per minute. • A 2.5 hour movie (highest quality video) 4000 MB (4 GB); Can’t fit on a regular CD

  5. Storage Unit (Examples) • CD quality songs 50 minutes (600MB). • A 22 minute “South Park” video (mpg format) is 40 MB (very poor quality) • A higher quality video (mpg format) can take up as much as 10 MB per minute. • A 2.5 hour movie (highest quality video) 4000 MB (4 GB); Can’t fit on a regular CD • Message: DVD’s emerged out of necessity to store video. If there was a way to compress it on a CD…?

  6. Storage Devices • 3.5 Floppy (soon to be obsolete) 1.4 MB • Zip disk: 250MB + • CD ROM 700MB+ • DVD 5GB + • Hard disks 80GB+ Special disk racks that can hold up to 500GB in a standard tower case. • Message: There is a correspondence between the size of data and where its stored.

  7. The Real Problem: Transmission not Storage • Storage devices have kept up with the demand to store larger and larger databases. • and to store larger and larger media formats • The real problem is transmitting these large files over an Internet that has severe limitations. • The solution comes in two forms: • Compression algorithms for files that can not be split. • Fancy software and new protocols for delivering only the parts of the data that need to be sent.

  8. Types of Computers Historically, there are have been 5 different types of computers • Supercomputers (once a hot area, now 90% of the companies are out of business) • Custom multiple processors, complex architecture, Cray/SGI was the big player • Mainframe (still going strong, go figure?) • Highly fault tolerant, supports multiple users, never shuts off • Minicomputers are really just smaller mainframes • Microcomputers are PC’s and laptops • Generic components, cheap (in many ways), prone to crash • Workstations are PC’s but with expensive components • The buzz in the early 90’s, much better memory architecture than PC’s (Sun, SGI, HP, DEC, were the players), 1 year, 244 days and counting…. • Message: Nowadays, there is very little difference between the average home computer and the average computer used in business.

  9. Processors • 8086 Intel Processor (1980) 5 MHz 8 bit • 80286 Intel Processor (1984) 8 MHz 20 time faster 16 bit • 386 Processor (1988) 20 MHz 32 bit • 486 Processor (1991) 66 MHz 32 bit • Pentium (would have been 586) 200 MHz 64 bit(bought one in 1994 for $2400) • Pentium4 (2002) 2 GHz $1500 • Pentium4 (2003) 3.2 GHz $1000 • Message: There are a lot of messages here.

  10. Processors • Is Intel the only manufacturer of processors? • No! • IBM probably sells more processors but they are for other devices: cell phones, lab instruments, cars, etc. • Other processor manufacturers: • Apple (Mac) • Motorola • AMD • Sun Microsystems • Patriot Scientific Message: Computing is not just about PC’s

  11. Processor Speed • 1 MHz means that the processor cycles (i.e., processed an instruction 1,000,000 times per second). However, this is a very basic instruction. • Adding two numbers sometimes can require as many as 4 or 5 basic instructions • In theory, a 2 GHz processor should be able to perform 2 billion instructions in just one second. • In practice, it’ll do around 400 to 500 million • Why?

  12. Memory • Two kinds of memory: Storage and RAM • Storage: Hard Disk, CDRW, Zip disk, floppy • RAM (Random Access Memory): Memory chips used to store working programs and data. • RAM is much much faster than storage • Faster means the stored data can be delivered to the processor in less time. Message: Memory is currently the processing bottleneck. The memory can not deliver instructions to the processor fast enough.

  13. Miniaturization • The key to making processors and memory faster is to make them smaller • Smaller things are closer together. Thus, it takes less time for the signal to travel from one component to another. • Also, if your “wires” are very small you can connect thousands or millions of wires in a small space (bandwidth) • In about 6-7 years, we will reach a critical limit where it will be very very hard to make things smaller. • Currently, the big buzz is nanocell computers; the processor and its connections are built with units that are as small as a molecule (several atoms).

  14. Where are things going • Mobile computing • Computers in everything: beepers, phones, cars, even the fridge • How about a mini computer in your credit card? • Its already in development • Computers will be part of everything • X10 • Part of a new house, just like plumbing

  15. Theme • Even though processors are getting so fast and so cheap, we can NOT count on this to continue indefinitely. • There are two main issues: • We might hit a physical brick wall in terms of physical limitations on miniaturization • There is a need to put computer-like processors in devices that need to be • very small • very cheap

  16. Theme • Thus, the industry is eventually going to have to look into clever ways of making programs • more efficient • more reliable • Thus, there is a need for better • software engineering • more efficient integration of hardware and software.

  17. Homework • Skim through pages 38-60. • but concentrate on 41-53 (read these pages more carefully) • Read 110-114. • Next, we are going to study one detailed example of compression.

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