Merit Badge
Christopher Strauss
Frontier Trails District
Troop 132
Computers Merit Badge Webs
Course web for this class
Computers Merit Badge Course Web
Computers Merit Badge Requirements
Computers Merit Badge Proof of Completion
Instructor's Course Outline
Computers Merit Badge Take-home Worksheet
Resource Webs (listed on the Course Web)
Many other web resources are available –
just search on computers or some other term
in your favorite web search engine
History of Computers - Abacus
The first true calculating machine (before 400
BC) was the abacus
Napier’s Bones (circa 1617)
The Scottish inventor
of logarithms went on
to construct
calculating rods
(made from bone) that
perform multiplication
and division by simply
adding and
Led to slide rules
(1621 – Fr. Oughtred)
Charles Babbage’s “Difference
Machine” and “Analytical Engine”
1822 and 1833 designs
Prototype for modern
Four parts: Input device,
memory (store), processor
(mill), and an output
The difference machine
was actually built recently
at MIT.. and worked!!
Herman Hollerith’s
Punch Cards
Developed to win a contest by the Census Bureau to
improve census data processing after the 1880
census had taken seven years to tabulate.
They were used successfully in the 1890 U. S. Census
The concept was not THAT new – in France in 1801,
Joseph-Marie Jacquard invented an automatic loom
using punched cards for the control of the patterns in
the fabrics.
Herman Hollerith later formed the company that
became IBM (International Business Machines
Colossus Mark I (England),
Harvard Mark I, ENIAC, EDVAC
World War II: computers were
developed to break German
and Japanese message
codes and create firing tables
Technologies: central
processors were made up of
vacuum tubes
Beginning with the Harvard
Mark I, they could be reprogrammed by re-wiring with
plugs like a switchboard, or
with paper punch tape
De-bugging computers is born
9 September 1945 –
Ensign Grace Murray
Hopper (RADM, USN)
removed the first “bug”
from a electromagnetic
relay in the Harvard
Mark II where it had
been smashed, halting
the computer. She
taped the moth to a
page the log book.
1947 - William Shockley,
John Bardeen, and Walter
Brattain invent the
"transfer resistance"
device, later to be known
as the “transistor,” to
replace vacuum tubes
1951 – Magnetic-core
memory also replaces
tubes, making real-time
memory use practical
Remington Rand UNIVAC – 1951 Delivered to the Census Bureau
First mass-produced
computer (46 made)
The size of a one-car
garage (14’ x 8’ x 8.5’)
5,200 vacuum tubes
required a chilled water
air conditioning system
Government, GE,
insurance companies,
DuPont (scientific)
1956 Concordance of the
Bible (6 mos. vs. 30 yrs)
Integrated Circuit
1958 – Jack Kilby created the
first “integrated circuit” at
Texas Instruments to prove
that resistors and capacitors
could exist on the same
piece of semiconductor
material. His circuit consisted
of a sliver of poisonous
germanium with five
components linked by wires.
Germanium was soon
replaced by silicon (1961).
1971 - Federico Faggin,
Ted Hoff, and others at
Intel designed the 4004
microprocessor while
building a custom chip
for Busicom, a Japanese
calculator maker. The
4004 had 2,250
transistors, handling data
in four-bit chunks, and
could perform 60,000
operations per second.
Electronic Hobby Computers
evolve into Personal Computers!!
1975 - Electronics hobbyists buy
the earliest personal computer
MITS Altair 8800 (Intel 8080)
1976 - Consumer computers
arrive after several companies
begin large scale manufacturing
1976 - Apple Computer Apple II
1977 - Radio Shack TRS-80
Commodore PET
Heath H8, H9
1981 – IBM PC
Types of Computers
Special purpose (digital watch, emission control
computer, home security system)
General purpose (Mainframes, Minis, PCs)
Supercomputers (beginning with the CRAY I in
1976!! - massively parallel processing)
Mainframes (multi-user IBM, DEC, NCR, etc.)
Minicomputers (multi-user DEC, Sun, file servers)
Microcomputers (single-user personal computers)
NEW – wearable computers now in development
Uses for Computers
For supercomputers…
For mainframe computers…
Banking, library automation, flight scheduling, census
For minicomputers…
Weather forecasting, satellite tracking, research
Operate manufacturing plants, track orders and inventory,
multi-user applications, web, email, and database services
For microcomputers…
Spreadsheets, word processing, graphics, games,
Parts of a Computer
Central Processing Unit (CPU) is the “brain,”
and is some brand of microprocessor chip
The CPU is normally mounted in a plug-in socket on
the motherboard, a circuit board tying everything in
the computer together via an electronic “bus”
Co-processors are used to offload computing tasks
from the CPU, such as mathematics and graphics
Random Access Memory (RAM) and Read-Only
Memory (ROM) are also mounted here
Intel 4004 – 2,250 transistors; 8088 – 40,000; 80486 – 1
million; Pentium – 7 million; Pentium II – 30 million
ROM is permanent, often re-writable (CMOS)
RAM is transient unless permanently powered (Palm)
See PC Tech Guide for more details
Schematic Diagrams
What's in that Box web
Click-n-learn Guide to PC
PC Tech Guide
Dave's Guide
Input Devices (digitizers)
Keyboard (QUERTY, Dvorak, custom – an
alphanumeric symbol digitizer)
Mouse and other Pointing devices
Trackball, joystick, pressure-sensitive tablet,
touch screen – a location digitizer
Sound digitizer (microphone, MIDI device)
Scanner (an image digitizer)
Sensor (temperature, light, moisture, smoke,
movement, or other environmental digitizer)
Magnetic Storage
Sequential Access
Magnetic Tape
Reel-to-reel or cassette
Original microcomputer media,
now used for backups
Random Access
Floppy Disk (8”, 5 ¼”, 3.25”, etc.)
Hard Disk
Magnetic powder coating on flexible disk in sleeve
Drive contains an actuator and read-write head on arm
Magnetically coated metallic platters on high-speed spindle
Drive actuator with many floating read-write heads on arms
For more information see
How Hard Drives Work and
PC Tech Guide (where this
diagram came from ----- >)
CD-ROM (Compact-Disc Read-Only Memory)
Write laser burns pits into the surface of the disk
Read laser bounces light off the pitted surface
WORM – Write Once Read Many, or CD-R
Newest formats: CD-RW, DVD, DVD-RW
Capacity (newer media have higher capacities)
Compare the CD-ROM surface (left) to the DVD surface (right)
For more information see How CDs Work and PC Tech Guide
Typical Capacity
Equivalent Size
High-density disk
1.4 megabytes
720 typed pages
Hard Drive
80 megabytes
40,000 pages
540 megabytes
270,000 pages
4.5 gigabytes
Motion picture
Output Devices
Printers (the first output device) and Plotters
Impact (daisywheel) and dot-matrix
Thermal (early BW and color)
Laser (highest quality, BW and color)
Plotters (pens on moving arms like seismographs)
Ink-jet (color plotters lead to printers, some also thermal)
Analog: CRT (cathode-ray tube) – the “monitor”
Digital: LCD (liquid-crystal display) screens
Sound Card (digital to analog converter)
Modem (modulator-demodulator; another digital to
analog signal converter)
Computer Software
Three main categories of programs
Operating Systems
Control all of the computer’s basic operations
Application Programs
Perform specific jobs or tasks with the computer
Input, output, file, memory, and task management
Text-based (UNIX, CP/M, MS-DOS) and graphical (GUI) (Xerox
Star, Macintosh, X-Windows, Microsoft Windows)
Database manager, spreadsheet, word processor, page layout,
graphics, CAD, animation, sound, communications
Programming Languages
A program used to develop and write other
programs and applications
Programming Languages
Machine code (low-level code, object code)
Specific to the microprocessor (Z80, 6502, 8088)
An instruction set to move decimal data through the CPU
Assembly language is a mnemonic symbol set for the CPU
High-level languages
Source code
 Object oriented (modular) languages – C++, Java
Translated by a compiler into object code before run-time
…or translated by an interpreter into object code at runtime (MUCH slower – Basic, scripting languages like Perl,
JavaScript, VBScript, HTML, XML)
Programming Language Use
COBOL (COmmon Business Oriented Language) for business
data processing
FORTRAN (FORmula TRANslator) for scientific and engineering
BASIC (Beginner’s All-Purpose Symbolic instruction Code) for
educational and personal computing (NOTE: Visual Basic is now
widely used in business office automation to build client-server
applications and integrate them with office applications)
Pascal for educational and general-purpose (led to Ada, now
widely used in government and defense contracts)
C, C++ and Java for cross-platform portable, object oriented
(reusable modules) application and game development
Perl, JavaScript, VBScript, and MANY other scripting languages,
all interpreted, for system administration, web pages, data work
Data Storage: Text & Numbers
Computers use binary numbers (1’s and 0’s) to store data. One
digit is a bit; four are a nibble, eight are a byte. Integers (whole
numbers) can be stored directly in binary bytes.
 0 = 00000000
3 = 00000011
 1 = 00000001
4 = 00000100
 2 = 00000010
5 = 00000101
A byte can be translated into a decimal number by adding up the
decimal values indicated by “1’s” in the binary number
 128 64 32 16 8 4 2 1
decimal values
0 0 0 0 0 0 0 0 binary places (8-bit)
0 0 1 0 1 0 1 0 binary equals 42 decimal (32+8+2)
Additional translation schemes have been developed to match
character sets to decimal and binary, such as ASCII & EBCDIC
Data Storage: Text & Numbers
Text and numeric characters are stored as ASCII
(American Standard Code for Information
Interchange ) values, consisting of 128 different
decimal codes. Extended ASCII goes to 256
ASCII translates each letter and number into a
binary byte (8 bits) that the computer
"1" is ASCII decimal “49” and binary 00110001
"A" is ASCII decimal “65” and binary 01000001
“&” is ASCII decimal “38” and binary 00100110
“z” is ASCII decimal “122” and binary 01111010
ASCII Translation
ASCII Decimal
ASCII Binary
Data Storage: Pictures
Computer pictures are stored as millions of colored dots
called “pixels” (picture elements) that have to be translated
to an analog signal for an analog CRT monitor to display them
(LCD panels are already digital so no translation is required).
Each black & white pixel is either on or off; each color pixel is
three dots, Red, Green, and Blue (RGB) that combine to create a
color. Color pixel combinations range from 256 possible colors
to over 16.8 million colors (real, or true color).
The more pixels a picture has, the better it looks (it has a higher
resolution). Each pixel has an associated color and location on
the screen expressed in binary terms.
When stored, each pixel’s information is saved to disk separately.
In a true color (32 bit) pixel, 4 bytes are used to store the color
information for each dot in the pixel. For a 1600x1200-pixel
display this is 8-million bytes of video memory, stored as one
8mb disk file! (bit-depth in How Computer Monitors Work)
 For more detailed information see How Graphics Cards Work
A pixel
Color Displays
Color Displays
Intensity - Millions of colors
Red= 64
Green= 10
Blue= 168
CRT Display
LCD Display
Dot Trio
Aperture Grill
Slotted Mask
Enhanced Dot Pitch
Data Storage: Sound
Normal sound is made up of waves or vibrations.
Each sound wave has a wavelength (how far between
the waves) and amplitude (how high the wave is).
A mixed, analog waveform signal comes in to the sound card from a
source (microphone) and is processed in real-time by an analog-todigital converter (ADC) circuit chip to create a binary (digital) output
of 1s and 0s. This is done at a specified interval or “sampling
frequency” (i.e., 1/10th of a second).
The digital output from the ADC is further processed and
compressed by the digital sound processor (DSP), and the output
from the DSP is sent to the computer's CPU via the sound card
connections and the data bus on the motherboard.
Digital sound data is processed by the CPU and sent to the harddisk controller to be recorded on the hard-disk drive as a wav file.
Playback is a reversal of this process, using a a digital-to-analog
converter (DAC) circuit chip to play back the binary sound file.
 For more detailed information see How Sound Cards Work
Storing Sound
Sound waves are sampled at a constant rate (sample rate)
Amplitude (height) of the wave is stored.
The higher the sample rate the better the sound
The higher the sample rate the more data is stored
sample rate
to Digital
Sampling Rate
Samples per second
Sampling Accuracy
Number of possible Output
CD Audio
44.1 kHz
DVD Audio
192 kHz
Computers communicate if they are electronically connected,
have the appropriate software, and have common protocols
or rules for negotiating their communication.
 Computers are digital, as are networks, but phones and wireless
communications move data primarily as analog sound waves.
Modems translate digital information to analog sound for
transmission along telephone lines, and back to digital at the other
end. They must synchronize speeds, block sizes, and correct
errors during communications.
 Early modems were 300 baud (bits per second, or about 36
characters per second) 33.6 KBPS modems move over 4000 bytes
per second.
 Analog telephone lines are generally limited to modem speeds of
33.6 KBPS; new 56K modems and 64K to 128K ISDN connections
make use some of the digital aspects of modern telephone lines.
 DSL uses high frequency compression to achieve 1.5 mbps down;
Cable Modems can deliver 30-40 mbps of _shared_ bandwidth
Many computers make digital connections to a local area
network (LAN) or wide area network (WAN) via telephone
lines (twisted pair), coaxial cable, fiber optic cables, radio, or
wireless communications.
 Networks make it possible for large numbers of computers to
communicate with each other, and to share resources such as
files, applications, and devices.
 Networks manage digital traffic by moving data as packets, with
elaborate protocols for ordering or prioritizing them, checking
errors, and filtering.
 Local area networks can be configured as star networks, bus
networks, or token-ring networks
 Networks can be connected to WANs or to the Internet via
modem, ISDN, cable modem, satellite, and other devices
For more detailed information see How Ethernet Works
Network Configurations
IBM Compatible
Workstation Power Mac G4
Power Mac G4
Laptop computer
Bus Network connected to a Star Network
Electronic Mail (Email)
Email allows users to send and receive electronic messages
over any type of network or modem connection using a store
and forward methodology.
 Messages are uploaded to the local mail server, passed to the
recipient’s account on that server, or forwarded to an external mail
server over a number of “hops” via intermediate servers.
 Messages are downloaded by the recipient’s mail client from their
mail server when the messages arrive, or when the recipient
opens an active connection to that server from their client.
 Depending on the type of mail service, messages may remain on
the host mail server or be downloaded to the local computer.
Improved bandwidth for networks and the Internet has made
instant messaging and real-time chat a viable form of electronic
communication, and is making voice-over-IP practical as well.
For more detailed information see How Email Works
* POP, IMAP, and
some Web Email
servers store
email messages
and text-encoded
attachments as
text files in most
Web Mail Server
(HotMail, Yahoo,
AOL, etc.)
IMAP Server
(UNT EagleMail)
* Email moves
servers over
IMAP Client
(Outlook Express)
(IE or
Mail Server
POP3 Client
(Netscape, OE)
* The user reads
their email by
using some sort
of client software
to connect to the
mail server
POP3 Server
(your ISP)
* Proprietary
servers usually
store email
messages and
attachments in a
real database of
some form
Computers at Work
The computer industry is HUGE with many
opportunities in sales, development, manufacturing,
training, implementation, support, and consulting
Electrical engineers, electronics technicians, repairmen
Application designers, developers, support staff, instructors,
consultants, technical writers, and editors
Graphics designers, special effects, art and film technicians,
medical technicians, geosystems analysts, and any other
job where the individual primarily processes computerbased information
System administrators, network administrators, database
administrators, security analysts, communications
specialists, and outsourcing service providers
Jobs related to the use of robotics in manufacturing
Copyrights & Software Piracy
Software publishers have always taken pains to protect their
intellectual property.
 Most software is covered by copyright, meaning that it cannot be
copied without special permission from the author
Most commercial software packages have elaborate licensing
agreements, much more like leasing than buying
 Shareware, freeware, banner ware, ad ware, and open-source
software are all variations on the licensing of software
 Public-domain software is not copyrighted, and is free to be copied
and used
Copying software outside the limits of the licensing agreement is a
crime; the Software Publishers Association (now called SIIA) has
an extensive anti-piracy program and web site.
Often there will be a specific statement that you can make a backup

Computers Merit Badge - Boy Scout Troop 780