1. 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.
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 bits Example: ‘A’ =
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 (read these pages more carefully)
Read
Next, we are going to study one detailed example of compression.