Introduction to Computers - Ben Barbour

birdsowlSoftware and s/w Development

Dec 2, 2013 (3 years and 6 months ago)

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Using System
Software

Chapter 5

Announcements


Chapter 6 Homework is posted


Windows 7 Quiz Homework is removed



Chapter 5 Homework should be complete


Windows 7 Simulator Homework
should be complete

Objectives


Upgrade vs. Buy


Evaluating your system


CPU


RAM


Storage Devices


Video Card


Sound Card


System Reliability


To Buy or Upgrade


Things to
Consider


Moore’s Law


Cost of
Upgrade vs.
Buy


Time to install
software /
restore data


Needs vs.
Wants


http://en.wikipedia.org/wiki/Moore%27s_law

To Buy or Upgrade


Determine your ideal computer system


Assess existing computer’s subsystems


CPU


RAM


Storage Devices


Video


Audio


Consider training needs

Desktop


Hard to move


Less expensive


Harder to steal


Easier to upgrade


More upgrade options


Larger monitors


More powerful


Notebook


Portable


More expensive


Easily stolen


Difficult/Limited
upgrades


Prone to damage


Smaller display

Desktop vs. Notebook

How a computer works

How a computer works

How Does the CPU Work?


Control Unit


Arithmetic Logic Unit (ALU)


Cache (Pron. “cash”)


Machine Instruction Cycle


Fetch


Decode


Execute


Store

Single Core CPU Diagram

Dual Core CPU Diagram

Control Unit


Coordinates all the activities of the CPU


Responsible for the effective speed of a CPU


Contains the “Clock”


Clock speed is measured in cycles per second, or Hertz.


1 Hertz (Hz) is equivalent to 1 cycle per second


1 cycle is roughly equivalent to 1 instruction per second


Responsible for coordinating the machine instruction
cycle

Arithmetic Logic Unit (ALU)


Responsible for performing arithmetic functions


Example:


Add, Subtract, Multiply, Divide


Performs logical functions as well


And, Or, Not,
Xor


Cache


Special memory reserved for storing frequently
accessed data/instructions


Divided into levels


L1


Closest to CPU core. Extremely fast


L2


Further from CPU core, shared between multiple
cores.


L3


Furthest from CPU, also larger and can hold more
information

CPU Register


Contains the current data being used by the current
instruction


Fastest possible data access for the CPU, nearly instant


All instructions and the data they need to work on are
copied into a register while being processed

Machine Instruction Cycle

1. Fetch

2.
Decode

3.
Execute

4. Store

Machine Instruction Cycle


Fetch: Gets the next instruction to be processed


Decode: Figures out what that instruction wants to do


Execute (Optional): Performs whatever actions
instruction demands


Store (Optional): If there is a result of an arithmetic
operation, that result should be saved



From the moment the machine is turned on, to the
moment is turned off, the CPU is looping through these
four modes.

Memory Access

Storage
RAM
Cache
Register
Memory Access Times

Storage

RAM

Cache

Register

CPU

Hyperthreading


Allows a single core to simulate multiple cores


Appears to the system as if there are actually two
cores present


Any time the CPU is idle (waiting on data from a disk or
memory for example), it can instead be given another
task to do



This makes it appear that two different programs are
being processed at the same time

Differentiating CPUs


Processing power:


Core: A complete processing unit (Control Unit, ALU)


Multi
-
Core: Multiple cores contained in the same chip


Clock speed: How quickly the processor works


Cache: The amount of immediate access memory the
CPU has


Front side bus: Connects the processor to system memory

Evaluating the CPU


Identify your current CPU


System properties, original documentation,
manufacturer’s website


Determine whether it is meeting your needs


During “normal use”, go to task manager and review CPU
usage


If over 90%, consider new CPU


A CPU upgrade for the average person is rarely
necessary

Random Access Memory
(RAM)


The type of memory module needed is determined by
the motherboard


Factors to consider


Operating System


Type


Speed


Maximum Capacity


Number of Modules


Timings (Advanced)


RAM: Types


Most RAM today is “Dual Inline Memory Modules”
(DIMM)


Uncommon:


SRAM


Static RAM (Not used in RAM anymore)


DRAM


Dynamic RAM


SDRAM


Sychronous

Dynamic RAM


Common:


DDR2 SDRAM


DDR3 SDRAM


Laptops use:


SO
-
DIMM DDR


RAM: Speed


Measured using two scales


Clock Speed / Data Rate: Measured in millions of
transfers per second


How many millions of pieces of information can be
transferred in a second


Example: DDR3
-
800 or DDR3
-
2133


Peak Transfer Rate: Measured in millions of bytes per
second


How many millions of bytes can be transferred in a second


Example: PC3
-
6400 or PC3
-
17000


Speed should match the specifications for the
motherboard

RAM: Capacity / Size


Motherboards will specify the maximum size per
module.


Typically: 1GB, 2GB, 4GB


A motherboard also has a finite number of slots
available to place memory. Usually a multiple of 2.


Typically: 2, 4, 6 or 8 slots


It is recommended to upgrade memory in pairs. That
is, buy 2 modules that are identical to the existing
modules. Do not mix & match. Do not buy just one
(some MBs do not allow odd numbers of modules)

RAM: Timings (Advanced)


Accessing RAM is much slower than a single instruction
cycle.


In some cases, a CPU can perform thousands of
operations in the same time it takes to retrieve one piece
of information from RAM


Timings refer to how fast data can be read and written


Measured in clock cycles for SDRAM, nanoseconds for
DRAM



Example: 5
-
5
-
5


5 clock cycles between asking for data and beginning to
recieve

it


RAM is used for
both the OS
and all
currently
running

applications


Should aim to
never use more
than 50% of
available
memory on
average

Application

Recommended RAM

Windows 7

2,048 MB (2GB)

Office 2010

512 MB

Internet Explorer

512

MB

iTunes

1,024

MB (1GB)

Total:

4096 GB

How much RAM do you
need?

How much RAM do you
need?


Operating System


Due to the limitations of 32
-
bit systems, memory over 4GB
is not used. Upgrading a 32
-
bit OS beyond 4GB will have
no effect.

Storage


Nonvolatile storage


Persists when computer is turned off


Types of storage devices


Hard drive


USB flash drive


Optical drive (CD/DVD/
Bluray
)


How a Hard Drive works


Composed of coated platters stacked on a spindle


Data (0’s and 1’s) saved to the disk in a pattern of
magnetized locations


Read/write head and platters combine movements to
access all areas of the platter.

Hard Drive (HDD)


Things to consider


Type


Interface type


Size


RPM (rotations per minute)


Access & Seek time


Data transfer rate

HDD Type


Traditional Hard Disk vs. Solid State Disk


Traditional


Much higher storage capacity


Very cheap $ to GB ratio


Solid State Disk (SSD)


Very expensive (nearly $1/GB)


Lower storage capacity (for now)


Extremely fast


Durable (no moving parts)

Interface Type


ATA


Asynchronous Transfer Attachment


SATA


Serial Asynchronous Transfer Attachment


SCSI


Small Computer Serial Interface



Most common


SATA


Size


Windows limits by default a single storage disk to 2TB
(Terabytes)


Hard drives currently reach 4TB of storage space and
growing


Your book states 2TB is the max, it is not.



Measures how fast the
disk can spin


Helps determine access
and seek times



SSD: Does not rotate


RPM

Seek Time

15,000

2ms

10,000

3ms

7,200

4.1ms

5,400

5.6ms

4,800

6.3ms

Rotations Per Minute (RPM)

Access & Seek Time


Measured in milliseconds


Seek Time


Measures how long it takes to locate the requested data on
the hard drive


Averages roughly 3
-
5ms for good drives


SSD: No seek time!


Access Time


Measures how long it takes for a drive to retrieve a piece of
information


Averages roughly 9
-
12ms (less than 9 is good)


SSD: Roughly 100 microseconds (0.1ms, 900x faster than HDD)


Data Transfer Rate


Measures, in bytes, how fast data can be transferred
per second.


Manufacturers report the theoretical maximum speed
under ideal conditions


Good HDD are between 80 and 100+MB/s


SSD: Average 500
-
600MB/s up to several GB/s

Evaluating Storage


Identify your hard drive’s total capacity


Determine your current storage usage / needs.


More flexibility with HDD choices when upgrading


HDD choice is limited only by connector type for the
motherboard


Nearly all consumer computers these days use SATA


You choose speed and capacity based on budget

Optical Storage


Optical media (read/written by laser)


Pre
-
recorded media


CD
-
ROM
, DVD
-
ROM
, BD
-
ROM


Recordable media


CD
-
R
, DVD
-
R
, BD
-
R


Rewritable (write many times) media


CD
-
RW
, DVD
-
RW
, BD
-
RE



Very rarely upgrade optical storage. Most common
device: DVD
-
RW

Video


Two components


Video Card


Display



Factors to consider


Computer Usage: Video Games vs. Traditional
Productivity


Display input connection


Number of displays

How does a video card
work?


Converts binary data into an image


Contains special hardware to convert 3 dimensional
information into an image very, very quickly


Contains special memory designed to work with the
video hardware


While a CPU core does only 1 instruction at a time, a
GPU can do millions of instructions at the same time



Also called a Graphics Processing Unit (GPU)

Graphics Processing Unit


Works side
-
by
-
side with the CPU to control video output


Two primary manufacturers: NVidia, AMD (ATI)


Will provide minor improvements to productivity display,
especially on Windows 8.


Is not necessary for day to day average computer usage


Essential to video games. Most modern games require an
expensive video card and will not function without one.



Book correction: The GPU does
*not*

perform the same computational work that
CPU performs. GPUs work in a very special way to convert 3D data into a 2D
image to display on your monitor.

Evaluating Video


Decide if you want to play modern video games


Simple games such as Facebook games and other
browser based games do not require expensive video
cards


Decide if you want to support multiple monitors


Most video cards will support up to 2 monitors


Determine your budget


Video card prices range from $50 to $800. The price of
the card more
-
or
-
less relates to the types of games you
want to play.

Evaluating Audio


Sound cards convert digital data into sound


Sound cards


Most every computer system supports at least 2 stereo
speakers


Most computer post
-
2007 supports 5.1 or 7.1 surround sound



A sound card will not improve system performance.
Sound cards today are mostly used for audio
professionals such as music studios and audiophiles.


Rule of thumb: If you can hear the difference, and it
bothers you, between a CD recording and an MP3
player, you might consider an advanced sound card.

Evaluating System Reliability


Performance Problems


Slow


Freezes


Crashes


Upkeep and maintenance


System tools


Control panel


Update software

Upkeep and Maintenance


How to speed up your computer


Remove unnecessary programs from startup folder


Delete unnecessary files


Run spyware and adware removal programs


Run disk defragmenter (rarely)

Update Software


Software updates improve reliability and security


Make certain you are running Windows Updates


Update Flash and Java

The Last Resort


Reinstall OS



The decision is based on cost vs. time


All problems on a computer can technically be solved
given enough time and the right technician, but can you
wait?


Remember, time = money!

The New Computer Effect


Beware the new computer effect!


A new computer at home or at work can artificially
influence your perceptions


Use the diagnostic tools at your disposal to determine
if you really do require an upgrade before spending
the money

The Upgrade Bottom Line


Audio, Optical, and CPU upgrades are extremely rare
today. Most of these are “Upgraded” only when a
new system is purchased.


Increasing storage capacity will not improve system
performance unless you have reached capacity.



RAM is the most cost effective way to improve
performance


A new video card can significantly improve gaming
performance, even in older systems