• 1 BIT, 8 BIT, 16 BIT • DIGITAL (10, 14) • K or KILOBYTE (3) • PUBLIC DOMAIN (13)
• 24 BIT COLOR (9, 14) • DISK DRIVE (6) • LASER DISC (12) • RAM (1) ROM (2)
• ANALOG (10) • DOS (8) • LASER PRINTER • SCANNERS (15)
• ASCII (5) • DOT MATRIX (9) • MEGABYTE (3) • SCSI INTERFACE (2)
• BASE TWO (4) • DVD (12,13) • MIDI (11) • SECTORS,TRACKS (6)
• BAUD RATE (11) • FIREWIRE (15) • MODEM (10) • SERIAL (9)
• BINARY CODE (4) • FLOPPY DISK (6) • MONITOR (8) • SHAREWARE (12,13)
• BIT (3) • GIGABYTE (3) • MOTHERBOARD (2) • STAR NETWORK (14)
• BYTE (2) • GRAY SCALE (15) • NETWORK (14) • TCP (11)
• CD ROM (12) • HARD DISK (7) • NYBBLE (5) • TERABYTE (3)
• CODEC (16) • HEXADECIMAL (5) • OCR (15) • USB (15)
• COMMERCIAL (13) • HTML (16) • PARALLEL (9) • VIDEO BOARD (2)
• CPU (1) • INKJET PRINTER (9) • PHOTO CD (15) • VIRUSES (13)
• CRT (8) • INTERFACE (2) • PIXEL (8,9,14) • VIDEO CONFERENCE (16)
• DAISY CHAIN (15) • PRINTERS (9) • ZIP DRIVES (8)
CPU: The CPU is the Central Processing Unit. It resides on one or more chips inside the computer. Each chip is a grid of silicon wires encased in a plastic container about the size of a fingernail. Although there are other chips involved and this is an oversimplification, it works well to think of the CPU as the CENTRAL component of your system. It functions the way your brain functions, coordinating the activities of the other devices. Although computers with vacuum tubes go back to 1946, the first microprocessor— i.e. computer on a chip was invented by Ted Hoff from Intel Corp in 1971.1
Another important chip — the RAM chip — is always blank when the electricity is off. When you start up a computer and begin to work, the information you type as well as the program that is in process all fit inside of RAM. When people refer to a 32 meg or 128 meg computer, they are referring to the size of the RAM capacity. RAM stands for Random Access Memory. A typical Mac or Windows computer now comes with 64-128 meg of RAM, i.e. the equivalent of 64-128 million pages of notebook paper. Older Macs and PCs in the early 1990s came with 1 meg of RAM. In the mid 1980s, typical computers had about 1/8 the of a meg of
RAM (128K) and very primitive graphics. The first microcomputer in 1975 (Altair) had under 1K of RAM which is about 1/1,000th of a meg. Gordon Moore, former CEO of INTEL and mentor of Andrew Grove (TIME magazine Man of the year 12/97) gets credit for what is now called “Moore's Law” — chip power doubling roughly every 2 years and costs falling by 50%.2 Those of us who bought computers in the 1980s can clearly attest to the truth of Moore’s law!
ROM chips are crucial to the computer, but not very interesting to us as consumers. A ROM chip typically contains “frozen” information (fairly technical, esoteric stuff) that the manufacturer wants accessible at all times. BASIC, however, was built into ROM on the Apple II so that if you turned on that CPU without a disk drive, you could actually start programming. ROM stands for Read Only Memory. ROM chips are found not only in computers; many appliances and even toys contain ROM chips. In fact, the singing bass, Big Mouth Billie, contains a ROM chip.
In order for the CPU and other chips to talk to other devices, an Interface board is used to connect the electronics of one machine to another. The board contains a printed circuit with a few special purpose chips. The innovation of the MacPlus back in 1987 was that it had a SCSI Interface built-in, allowing for easy connection to hard disk drives. The technology rivalry between the East Coast (Rt 128 beltway) and West Coast (Silicon Valley3 area) was symbolized by the pronunciation of the word SCSI. East Coasters wanted to pronounce it as "sexy" while West Coasters wanted “scuzzy.” As the Lakers proved more often in the 1980s, the West won and “scuzzy” became the accepted pronunciation. By the way SCSI stands for Small Computer System Interface, increasingly another obsolete word, since USB is taking over (see page 15) as the faster, preferred way for data to travel!
One special interface board — the Video Board — connects the computer to the screen; it frequently has multi-colored wires emerging from it, typically RGB for red, green and blue. Although most of us mixed the primary paint colors (red, green and yellow) to make other paint colors, it turns out that the primary colors for electron beams are red, green and blue! Another important board — the Motherboard — is the main circuit board that all the RAM Chips, ROM Chips and other Interface Boards plug into.
Both the computer chip and the disk drive store information that is coded electronically. The basic unit of information is the Byte which is equivalent to one character or symbol of text. For example, the word “Hello” is a 5 byte word. Because spaces are just as significant as letters, “New York” is one 8 Byte word, which is the way most New Yorkers say it anyway. In fact, it is very useful in teaching or learning word processing to realize that Space Bar and Return each constitutes 1 Byte; you might say that the computer alphabet has 29 letters: A-Z, Space Bar, Tab and Return. Use the “show invisibles” command in your word processor to see all of these 29 letters!
world. The web server contains over 1 terabyte (“of the terra”) stored in a database of 173.6 million rows. One Terabyte contains 1,000 gigabytes (about 1500 CDs) or about 1 million floppy disks!
This chart summarizes basic computer literacy for various disks
• double density floppy disk 800K 800,000 bytes .8 meg
• high density floppy disk 1,400K 1,400,000 bytes 1.4 meg
• typical hard disk drive 20,000,000K 20,000,000,000 bytes 20,000 meg 20 gig
• CD ROM disk 650,000K 650,000,000 650 meg over 1/2 gig
How is each byte coded? Although this topic is not particularly useful, many people find it interesting. Via magnetism, it is possible to magnetize a spot on the plastic floppy disk or a piece of wire to be either ON or OFF. The inside of a chip looks like a huge grid of horizontal and vertical wires.
Consider a 1 inch chip that has 100 horizontal wires and 100 vertical wires. It looks like a gigantic tic-tac-toe board with 10,000 different junction spots or intersection points. Imagine that each one can be TURNED ON or OFF with magnetism, behaving like a light bulb. Let us call each junction of wires a Bit and let us think of grouping the thousands of Bits into groups of 8.
Using groups of 8 Bits at a time, we have a picture that looks like this:
| | | | | | | |
-•- -•- -•- -•- -•- -•- -•- -•-
| | | | | | | |
It turns out that we can design a code of ONs and OFFs so that each group of 8 Bits holds one letter or symbol of the English alphabet. How? Well, first let’s figure out how many different patterns of ON and OFF we would find with 8 Bits lined up. If we had just a 2 bit computer, we might have 4 different patterns for the 2 spots: ON-ON • •
ON-OFF • o
OFF-ON o •
OFF-OFF o o
If we had just a 3 bit computer, we might have 8 different patterns for the 3 spots:
ON-ON-ON • • • OFF-OFF-ON o o •
ON-ON-OFF • • o OFF-OFF-OFF o o o
ON-OFF-ON • o • OFF-ON-ON o • •
ON-OFF-OFF • o o OFF-ON-OFF o • o
Using the symbols 1 for ON and 0 for off simplifies the explanation:
A 2-bit computer has 4 patterns: 00 01 10 11
A 3-bit computer has 8 patterns: 000 001 010 011 100 101 110 111
A 4-bit computer has 16 patterns:
0000 0001 0010 0011 0100 0101 0110 0111
0001 1001 1010 1011 1100 1101 1110 1111
This system of 1’s and O’s is really the Base Two or Binary number system in math; the word Bit is an acronym of the phrase BInary digiT.
Here are the numbers from 1 to 14 written in Base 
Two:
0001 = 1 1000 = 8
0010 = 2 1001 = 9
0011 = 3 1010 = 10
0100 = 4 1011 = 11
0101 = 5 1100 = 12
0110 = 6 1101 = 13
0111 = 7 1110 = 14
Here is Larry Bird’s uniform number (33) written
as a BASE TWO number:
100001
Each position stands for a power of TWO instead of a power of TEN:
Now let’s figure out how many patterns in an 8 bit computer? Since a 2 bit computer has 4 patterns and a 4 bit computer has 8 patterns, can you see that the number of patterns doubles as we add a bit. Can you figure out a good rationale for why it is so?
Take the 8 patterns for a 3 bit computer. Put a zero in front of each pattern or put a one in front of each pattern — you get the 16 patterns that for a 4 bit computer. The end result is that an 8 bit computer has 256 patterns. Each one is equal to one letter of the alphabet, a symbol on the keyboard or perhaps even a graphics character. Some of the 256 patterns may even be left unused. This provides another way to understand a Byte. A byte is made up of 8 bits and is a coded way of representing one letter of the alphabet.
Example #1: let us change 89 from decimal to binary
The typical strategy is to write down 8 places, labeling them from 1 on the right to 128 on the left:
We now distribute the 89 (as if we playing the role of the banker in monopoly and have to pay $89 but can use only $128 bills, $64 bills, $32 bills, etc. and just ONE of each) We first put a 1 in the 64’s place which leaves 89-64 or 25 left to distribute. We next put a 1 in the 16’s place, leaving 9 dollars and so on. We get an answer of 01011001.
Example #2: change 01000101 from binary to decimal
We begin with our 8 positions
and now translate our 01000101 number into 1 in the 64 place PLUS 1 in the 4 place PLUS 1 in the 1’s place, i.e. with our “monopoly money analogy” $64 + $4 + $1. We get an answer of 69.
Example #3: interpret the months and date on this wedding ring on the right. The 110 represents 6 (June) since there are 1’s in the 2’s place and the 4’s place. The 110 represents 4 since there is a 1 in the 4’s place and 0’s in the 1’s place and the 2’s place. We get an answer of June 4th.
Example #4: Consider the 3 byte word Yes (which is what most Boston Celtics fans said when Rick Pitino quit his job as the coach.) This word is made of
3 bytes or 24 bits or 6 nybbles (yes, the word Nybble is legitimate — though esoteric — and means 4 bits or half of a byte). And so Rick can teach his children that 8 bits make a byte, 4 bits make a Nybble and 2 nybbles make a byte.
When you type the word YES on your computer, each letter is translated into its 8 bit code. Each ASCII code is 1 byte made up of 8 bits:
Y Code 89 = 01011001 OFF ON OFF ON ON OFF OFF ON o•o••oo•
E Code 69 = 01000101 OFF ON OFF OFF OFF ON OFF ON o•ooo•o•
S Code 83 = 01010011 OFF ON OFF ON OFF OFF ON ON o•o•oo••
The computer is therefore storing 3 bytes of information to remember the word YES. Since each byte is made of 8 bits, the computer is storing the 3 bytes as a series of 24 bits. If we are looking at a disk, we would be referring to 24 spots of magnetism on one of the circular “tracks” of the record. Inside a chip, we would be referring to 24 intersections of wires on the grid.
As mentioned above, the most common coding system for relating binary numbers to English symbols is called the ASCII system. It means that A is code 65, B is code 66 and so on ... through Z which is code 90. ASCII stands for American Standard Coding Information Interchange (pronounced “ass-key”) and it proves that the computer industry is not completely idiosyncratic and eccentric! Now that you know that A is code 65, look back at the word YES and see if the three ASCII Codes (89, 69, 83) make sense.
Another computer system for coding numbers is called Hexadecimal or base 16. In this system we use one symbol for each number from 1 to 15; we use A for 10, B for 11, C for 12, D for 13, E for 14 and F for 15. In the Hexadecimal system, after the one’s place we have the 16’s place, so the number A3 means 3 in the ONEs place and A (or 10) in the 16’s PLACE, i.e. A3 = 10x16 + 3 = 163. Let’s compare the 3 number systems:
decimal binary hexadecimal
called base 10 called base 2 called base 16
10 symbols used: 0 to 9 2 symbols used: 0 & 1 16 symbols used 0-9
and A,B,C,D,E,F
100,10 & 1’s place 4,2 & 1’s place 256,16 & 1’s place
Below are the ASCII codes for the common 26 uppercase letters of the alphabet, A to Z, together with their Binary and Hexadecimal equivalents. On the old ImageWriter printer, if you turned on the machine incorrectly, you got a series of 2-character hexadecimal codes. If the printout was
4C 41 52 52 59 20 42 49 52 44 20 47 4F 20 44 41 4C 4C 41 53 0D
you can decipher using this chart what was really typed (20=SPACE BAR and 0D=RETURN).
• Thanks to Theresa Overall from Lamplighter School (Dallas, TX) for fixing this coded message •
ASCII Binary Hexadecimal ASCII Binary Hexadecimal
Letter Code Equivalent Equivalent Letter Code Equivalent Equivalent
A 65 01000001 41 N 78 01001110 4E
B 66 01000010 42 O 79 01001111 4F
C 67 01000011 43 P 80 01010000 50
D 68 01000100 44 Q 81 01010001 51
E 69 01000101 45 R 82 01010010 52
F 70 01000110 46 S 83 01010011 53
G 71 01000111 47 T 84 01010100 54
H 72 01001000 48 U 85 01010101 55
I 73 01001001 49 V 86 01010110 56
J 74 01001010 4A W 87 01010111 57
K 75 01001011 4B X 88 01011000 58
L 76 01001100 4C Y 89 01011001 59
M 77 01001101 4D Z 90 01011010 5A
Example #5: let us make sense of the use of hexadecimal numbers in the HTML command
<BODY BGCOLOR = "#33B42D" TEXT= "#ABCDEF" > a command that is fancier than but similar to <BODY BGCOLOR="NAVY" TEXT="FUCHSIA">
Solution: the programmer is using hexadecimal numbers (base 16) to represent the mixture of RGB on the web page — 33 drops of red plus B4 drops of green plus 2D drops of blue. The 3 numbers 33, B4 and 2D are hexadecimal numbers which means that the positions are the ONES place and the SIXTEENS place. 33 therefore is 3x16 + 3 or 49. B4 therefore is 11x16 + 4 or 180 and 2D would be 2x16 + 14 or 46. Remember that in the hexadecimal alphabet A stands for 10, B stands for 11 and so on. Can you figure out amounts RGB intended for the text color of ABCDEF?
Exercises: Change 133 and 233 from decimal to binary and hexadecimal. Change BIRD into a series of ASCII numbers, a series of binary codes and a series of hexadecimal codes.
Disk Drive: This storage device holds the floppy disks. Each Floppy Disk is actually a circular record encased in a square shell. The record is divided into concentric circles called tracks. Each Track is divided into chunks of information called Sectors. In the mid-1980s (when the Boston Celtics were good), the most common size disk was the 5.25" floppy which truly flopped! Apple II computers held 140K. PC computers held 360K or 1200K. In the late-1980s, the 3.5" floppy became popular. The original one hole, regular density held 800K (800,000 bytes or 4/5 of a megabyte). Even though the casing is hard plastic, these 3.5" Floppy Disks are not called hard disks; the inside plastic circular record really does flop! All 3.5" disks now hold 1400K (1,400,000 bytes or 1.4 megabytes) and are identified with the HD symbol as well as having 2 holes in each of the 2 top corners. Most new Macs are now floppyless. Soon the floppy disk drive will be one more trivia question; the new song at Disneyworld may soon be “its a diskless, diskless world.”
Why was it so hard to convert files between Macs and PCs?
Answer #1: the number of tracks and sectors on each computer is different, so that when you insert a Mac floppy into a standard Windows computer, the machine wants to format the floppy. However, if you have installed “booster” software for your Windows machine (e.g. MacOpener or Conversions Plus by DataViz), then your Mac floppy will show up with its list of files on your Windows machine. Because PC Exchange is a standard part of theMac operating system,then your Windows floppy will show up with a "PC" in its icon. on the Mac screen.
Answer #2: just because the files show up, it does not mean that they will load up on the other computer. It depends on whether your specific word processor can “read
” the file from the “other” word processor. That is why we tell people to save your file in multiple formats (using Save As) if you intend to try to load up the file on another computer. Example: you create a letter to Antoine Walker on your Mac. You save it in AppleWorks as Walker1. You insert the floppy disk into a Windows machine boosted with MacOpener. It shows up as Walker1 but you are frustrated in loading up the file. You need to go back to your Mac, load up the file and now choose Save As, creating several files (Walker2.doc, Walker3.rtf, Walker4.txt) and then return to your Windows computer. By saving from within AppleWorks in multiple file formats (e.g. Walker2 in word format, Walker3 in rich text format, Walker4 in text or ascii format), then it is much more likely that your Windows computer can load the file. You still might need to load the software first, then choose open.
Hard Disks: It is best to think of a hard disk drive as a circular piece of metal that has been sealed in a dust free environment. You do not remove a hard disk; you do not handle it. You can save or load onto the hard disk and move programs and files from your floppy drive to and from the hard disk. We use the words Hard Disk and Hard Drive interchangeably. Because a hard disk is sealed in a special environment, it can spin faster and store more information. Generally, a hard drive consists of several metal platters, separated by about 1/8th of an inch. A typical hard disk drive in 1987 held 80 megabytes and cost $1400. A typical external hard disk drive in 2001 holds 20 gigabytes and costs under $500. To facilitate the use of IMovie, we recently purchased four 60 gigabyte firewire hard drives (see page 15) for about $350 each. These four hard drives -- by the way -- add up to about 1/4 of a terabyte!
Zip Disks and SuperDisk: The external zip drives by www.iomega.com attach to your Mac or PC and allow you to store 100-250 megabytes (two types) on what some consumers think of as a “thick floppy.” The disk itself is portable, durable and just slightly bigger than a standard 3.5" floppy. Some manufacturers include zip drives as standard equipment, incorporated as an internal drive. The external superdrive LS-120 is multi-purpose, allowing you to read/write to a standard floppy or a superdisk which is the size of a floppy but hold 120 meg
DOS: This ancient acronym stands for Disk Operating System and it refers to the storage system for the particular disk. The old Apple III computer had the Sophisticated Operating System so people spoke of the Apple SOS (sauce). When Macs users refer to System 8.0 or 9.0 or X, they are referring to the DOS of their Mac. If you are over age 30, try to think of DOS as analogous to records playing at 33, 45 or 78 RPM; if you are under age 30, think of CDs vs DVDs. When you turn on a computer, the first thing that happens is that DOS is loaded from the hard drive into a portion of the RAM chip. Someone once remarked that DOS is like the "morning coffee" of a computer.
CRT: The CRT is the screen, sometimes called the Monitor. The letters stand for Cathode Ray Tube which is what old televisions used to be called. CRTs can be color, green or amber and have varying resolutions usually described as a rectangle of Pixels; each pixel is one dot on the screen. Most computers use a resolution of 72 dots per inch. For example, a 14" monitor might display 7" by 9" which would be 504 pixels by 648 pixels. Of course, the description of 14" is a rough approximation for the length of the diagonal of the screen.
Keep in mind that the resolution and/or color attributes are not just a function of the CRT, but also of the specific Video Board or Video Card that is on the motherboard.
1 bit color = black&white, 2 bit color= 4 shades, 4 bit color=16 shades
8 bit color = 256 shades, 16 bit color = thousands (65,536 colors)
24 bit color = millions (16.777,216 colors or 2 to the 24th power)
The resolution can be changed to user preferences so that more info is displayed on the screen in tinier size or less info on the screen with bigger size. This is different from the number of colors.
Printers in 1980 used to be impressive if they could print italics. Dot-Matrix printers such as the Imagewriter are now obsolete; they used a mechanism that printed tiny little dots on your paper, shaped into letters and numbers. The Laser printer resembles a photostat machine and produces superb quality text and graphics. The printer is a computer itself which directs a laser beam to charge a photostatically sensitive drum which then attracts the toner. Inkjet Printers are similar in function and quality to laser printers, but they are less expensive and slower. The inkjet printer sprays ink from a matrix of tiny jets. These printers are now capable of photo quality print-outs.
Printers originally were either Parallel or Serial, terms which refer to the way the data is sent from the computer to the print
er. If a byte is made of 8 bits, then a Parallel device sends the 8 bits marching on 8 separate wires, like a crowd of people marching 8-across down the street. In contrast, a Serial device sends the 8 bits in single file, with a code after each group of 8, e.g. each group of 8 children in single file with the last one in each group wearing a special hat. The only important consideration, however, as far as the consumer is concerned is to match your printer to the interface. Most Macs have two serial interface ports, labeled as printer and modem, one SCSI interface port but no parallel ports. That is why Mac owners buy the SCSI version of a Zip Drive. Most Windows computers have two serial interface ports (labeled as COM1 and COM2) and one parallel port (labeled as LPT1) but no SCSI port. That is why when you add a zip drive to a Windows computer, you buy the parallel model or else you have to add a SCSI interface. All of these factoids, unfortunately are now part of ancient history, since the 21st century is all about USB and Firewire (see page 15). Parallel, serial and SCSI will be remembered as vocabulary words for the grandparents version of trivial pursuit!
Analog vs. Digital is a fundamental conceptual distinction that used to be reserved for technical whizzes and now finds its way increasingly into everyday conversations. When a device functions Analog such as a standard clock with hands, the mechanism proceeds through every possible variation from one extreme to the other. If both hands are at the 12, it is midnight, but as the next few minutes pass, the big hand sweeps through every continuous position on its way to being 5 past midnight. Analog devices are like continuous functions in math. Other examples would include a rotary dial on a radio that finds every frequency from 580 to 1490 as it is turned, a mercury thermometer or an oven rotary dial in which you estimate 375 degrees.
On the other hand, Digital means that the variations have been converted into discrete numbers, with a definite step from one to the next. Digital devices are not just watches. Musical compact disks contain magnetic 1’s and 0’s in the grooves, so that the music is in effect coded and digitized. Old-fashioned LP records, VCR tapes and audio tapes are Analog while CDs and DVDs are Digital .
MODEMS: The MODEM allows your computer to communicate via the telephone with other systems. Sometimes the MODEM is the size of a small box, sometimes it is a board that fits inside your computer unit. The acronym MODEM stands for MOdulator DEModulator, since it “modulates” analog into digital and visa versa. Typically the MODEM box has one cable connected to your computer. A standard phone cable attaches from the MODEM to the phone jack; additionally, you can usually plug in a standard telephone into the MODEM, allowing you to use the telephone line for either voice or data communications. Once your computer is hooked up via MODEM to your phone line, you can communicate with another computer via its MODEM.
BAUD RATE means the rate at which the data travels on the phone line. Baud means bits per second, so a Baud Rate of 14,400 baud (usually pronounced "14.4") means 14,400 bits per second (i.e. 1,800 bytes); this is almost 2 pages of text double-spaced per second. Originally, modems were between 300 and 2400 baud and cost over $300. Now 57,600 baud modems are under $100.
Going On-Line involves multiple costs which increasingly drives home owners towards using cable modems or DSL lines and driving schools towards having T1 and fractional T1 direct access lines to the the internet.Cost #1 might be to gain access to services. Most services (Earthlink, America OnLine) or Internet Service Providers charge a flat fee per month of $10-$30. If you are not located near a big city, you will accumulate cost #2 — long distance charges from the phone company. Make sure your phone line is designated for unlimited local calls! One school we know made this mistake and accumulated a $800 phone bill for several months of local phone calls.
Cost #3 involves each new phone line you may need. Many home owners make the mistake of thinking a modem in the house requires another phone line; it doesn't!
Increasingly, many computer users have moved from modem services such as America OnLine to Internet Service Providers (frequently referred to as ISPs) and cable modems. When you connect to an ISP you get access to the Internet via what is called TCP. TCP means that your computer at home is now acting as if it were directly cabled to millions of other machines around the world. TCP stands for Transfer Control Protocol. When a school “gets wired” via fiber and hubs directly to the Internet, the school’s computers have the potential to access the web at faster than typical modem speeds. ISDN lines of 64K and 128K or fractional T1 lines of 256K refer to the speed of data transfer in baud rate, just like 56.6 modems. Other options are Cable Modems, offered by local cable services, or DLS modems offered by a variety of phone companies. See Chapter 14 entitled Get on the Web for further discussion of internet access.
Every computer on the web has an IP address, either fixed or randomly assigned. IP stands for Internet Protocol. A typical IP address is a series of numbers (e.g. 207.31.250.18) which can then be turned into a name (e.g. bbs.nobles.edu). Fixed IP numbers used to be common but are increasingly hot commodities, with most ISPs, businesses and schools serving up what are called random IPs using a DHCP server. DHCP stands for Dynamic Host Configuration Protocol; two commands built into the RUN feature of PCs illustrate what IP numbers are all about. By typing PING XXX or TRACERT YYY with XXX or YYY being a specific IP number, you will find out how many milliseconds (millionths of a second) it takes to send a signal to that computer and back. Don’t forget that electricity travels around the equator of the earth in 1/7th of a second!
It is a mind boggling reality of the internet and the web that all the data travels in PACKETS from one computer to another, frequently stopping at many places in between:
Mac users can thank Bryan Christianson for the free program WhatRoute which gives us the intriguing ping and trace route features in a free program (web site: crash.ihug.co.nz/~bryanc/)
MIDI stands for MUSICAL INSTRUMENT DIGITAL INTERFACE. A MIDI connector plugs into your computer, typically from an electronic keyboard. Some keyboards are MIDI compatible, though cheap ones are not. Once you have connected your music keyboard to your computer, you can enter notes on the screen via the piano keyboard. The minimum cost used to be about $300-$400 for the midi-compatible piano keyboard and $75 for the midi-interface external cable which connects from the computer's modem port to that keyboard. Then you need music software that has midi features; this can range from $50 to $600.
A CD ROM holds up to 650-680 megabytes (over 1/2 a gigabyte), the equivalent of about 465 high density 1.4 meg floppy disks. In basketball terms, this represents a stack of typewriter pages the height of the Fleet Center. Initially, computer CDs were read-only; you did not record onto them, but only get information from them. Educational software on CDs remains read-only. However, more and more computers now give you the ability to save onto CDs because many computers now come standard with CD-RW, which can both Read and Write CDs.
Voice Digitizers allow you to record voices and sounds and do something like word processing on the recorded sound. The package usually consists of a microphone and software that turns the sounds into 1’s and 0’s to be stored in RAM and on a disk. Once the sound is turned into a wave form on your screen, the software may allow special effects such as reversing the sound, amplifying it, making it reverb as if it from outer space or a concert hall.
A Laser Disc Player looked like a VCR and plays video and audio images, although CDs and DVDs have moved laser discs into the technology graveyard! A laser disc may contain thousands of frames from an art gallery with software to search by style, artist, chronology, etc.
DVD stands for DIGITAL VERSATILE DISK and gives us a chance to use 4.7 gigabytes and 17 gigabytes in our everyday vocabulary! DVD discs make CDs look like the 5 1/4" floppy disks of earlier times. Just the single sided, single layer DVD disc itself offers 4.7 GB of capacity, which is worlds away from a CD’s 680 MB capacity. When we start discussing the 17.0 GB capacity of the double sided, dual layer DVD, it's like comparing the scribbles of a one-year old toddler to a Monet masterpiece.
Encountering Computer Viruses is now common to many of us. To simplify, one might say that a Computer Virus is comparable to a special device inserted into the carburetor of a car by a dishonest mechanic. Even worse would be if the car mechanic wired your car so that whenever you park next to another car, the problem in your car jumps and spreads to the next car. In other words, computer viruses can jump from disk to disk, spread via internet downloads or even worse now via macros in Microsoft documents and e-mails. Who creates these things? Sometimes teenagers and sometimes adults. A computer virus can be defined as a computer program that does something strange to your files and disks and spreads to other computers via e-mail, networking and floppies. Daily e-mails warn of new viruses and now reports of the disasters incurred by viruses spreading throughout networks appear regularly on the Six O’Clock News. One article used the metaphor of “cowboy culture of hacking” to describe this phenomenon!
For under $100, you can buy a reliable, relatively easy virus program (e.g. SAM, Norton, McAfee AntiVirus) that will disinfect existing hard disk drives and prevent subsequent viruses from coming back. Public Domain programs are available to download at sites like www.download.com and commercial programs are available at sites like www.mcafee.com.Public Domain software means that it can be copied and distributed freely. This is in contrast to Commercial Software which is copyrighted and for which it is illegal and dishonest to distribute. Shareware software can be distributed but users are honor bound to pay for it or delete it after a short period of trial usage.
Trying to understand the size of Computer Graphic Files becomes an excellent exercise in synthesizing the concepts of bits, bytes, kilobytes, megabytes, and pixels. We begin by the fact that the screen resolution is generally 72 pixels per inch and so a one inch square would contain about 5,184 pixels (72x72).
• If you are working in “one-bit color” then each pixel can be only black or white so it occupies one bit, either 1 or 0. Therefore, 5,184 pixels would occupy 648 bytes (5,184/8) which is under 1K.
• If in “8-bit color” then each pixel can be one of 256 shades of gray or 256 colors (the number 256 is 2^8th power). This means that 5,184 pixels would occupy 5,184 bytes or approximately 5K.
• If in “16-bit color” then each pixel can be one of 65,536 colors (2^16th or 256 x 256). Thus 5,184 pixels would occupy 10,368 bytes, each pixel needing 2 bytes to store 1 color choice out of 65,536.
• If in “24-bit color” then each pixel can be one of 16,777,216 colors (the number 16,777,216 is 2^24th power ). This means that 5,184 pixels would
occupy 15,552 bytes, since each pixel would require 3 bytes to store its color choice out of 16,777,216 possibilities. By the way, the best way to picture 16.7 million colors is to think of mixing 256 shades of each primary color.
To test this out, we created a one inch square using Photoshop; it took 7,528 bytes to store the 8 bit color version, 14,027 bytes for the 16 bit color version and 3,125 bytes for the 1 bit version. Since other info is stored by Photoshop, this tends to validates the above theoretical discussion.
Here is the summary extended to a 2 and 3 inch squares; remember that when you double the length and width of a garden, you multiply its area by 4!
picture size one bit color 8 bit 16 bit 24 bit
1 inch square 2/3 of a K 5K 10K 15K
2 inch square 2.7 K 20K 40K 60K
3 inch square 8K 45K 90K 135K
And so that 3" square, 24 bit color picture would consume about 10% of a high density disk. And this is all at 72 PIXELS PER INCH which is the screen size and a low resolution for anyone doing serious graphic art!
If we work at 150 PIXELS PER INCH, then each number is quadrupled. If we choose to work at 300 PIXELS PER INCH, then that 3" square picture at 24 bit color consumes almost an entire high density disk!
Understanding Digital Sound (One second of stereo = 176K)4
With the solid base of bits and bytes, we are now able to understand how sound is stored digitally, e.g. CD or computer. A sampling rate of 44,100 means that the sound waves are “inspected” that many times each second to determine its qualities: note, tone and amplitude. There are 65,536 choices for each specific sampled sound. Since 65,536 = 256 x 256 and each byte has 256 patterns, this means that each sampled sound consumes 2 bytes of data. Thus 44,100 samples in one second would be 88,200 bytes or 88K. This now gets replicated for both the left and right channels (stereo), yielding 176K. Therefore one minute of data would be 60 x 176K or 10,560K, i.e. 10 megabytes. 65 min would therefore equal 650 megabytes, filling up a typical musical CD! To make a connection between digitizing art and music, the above chart shows that a 3 inch square graphic at 8 bit color contains about the same number of binary codes as one second of stereo sound!
Understanding MP3 files and MP3 players? Typical sound files are recorded as AIFF files with each 3 minute song that being about 33 megabytes. The MP3 file format compresses that file to about 1/10th of its size in the same way that JPEG and GIF provide compressed versions of quality graphics. And so each MP3 file is about 3 meg with virtually no difference in sound quality. These smaller files can be easily downloaded, moved via cable into a portable MP3 player or stored on a hard drive. MP3 comes from the word MPEG which stands for Moving Pictures Expert Group. MP3 is short for MPEG audio layer 3, the compression algorithm.
A Computer Network is physically cabling the various computers (let's call them A,B,C,D and E) together, either as a Daisy Chain (one wire from A to B, another wire from B to C, another wire from C to D, and a fourth wire from D to E) or as a Star (each wire from A,B,C,D and E runs directly to the hub in one central closet). On a network, you can share files, printers, CD-ROM drives and most importantly the connection to the web and the outside world!
A Scanner looks like a photostat machine and transfers a graphic from a photograph or drawing onto the screen. In effect, the scanning software digitizes the picture into 1’s and 0’s to be stored in the RAM chip and subsequently onto the disk drive. The Larry Bird graphic with 00100001 on his uniform involved each pixel being either black or white (1 BIT COLOR) and was poor quality like most of the pictures in this book. Gray Scale means that each pixel can be one of 256 shades of gray, e.g. the Larry Bird graphic at the end of this chapter. 8 Bit Color means that each pixel is 1 of 256 colors. 16 Bit Color means that each pixel is 1 of 65,536 colors. 24 Bit Color means that each pixel is 1 of 16,777,216 colors.
OCR Software is an enhancement to the traditional scanner functions that turns a printed page of text into an editable word processed document. Without OCR capability, your scan of a printed page would appear as a graphic. Using OCR software (which stands for OPTICAL CHARACTER RECOGNITION), you can scan text from a printed page and then edit it in word processor. Many scanners have OCR as an option.
Digital cameras store pictures or movies on memory cards or directly onto a floppy disk. For example, the Sony Mavica Cameras store its images on a floppy disk; each standard picture with a resolution of 640 x 480 or 307,200 pixels and 1024 x 768 or 786,432 pixels for higher resolution pictures. Note that these images are under 1 million pixels (which is called a megapixel).In contrast, the Olympus C-3000 camera is a more serious camera with a resolution that is twice the high resolution of the Mavica. Its resolution is 2048 x 1536 or 3145728 pixels or 3.3 megapixels. These images are stored onto a SmartMedia Card, basically a RAM chip on a card the size of a thick credit card (sold in sizes of 8 meg, 16 meg, 32 meg, 64 meg). These memory cards can then be inserted into a printer or a transfer device to move the files to a computer (via USB or serial). Most camera shops and services will transfer pictures onto CDs or floppy disks. Each Photo CD (up to 650 meg) holds about 80-100 images stored in multiple formats including 24 bit color. Or you can send your film to an online service, like www.ofoto.com, that will both process your photos and post your photos online so that you have access to the digital versions of your pictures. You can then download these images and use them in your word processing, slide presentation or HTML documents.
USB stands for Universal Serial Bus and just about all computers now come with one or more USB connector that lets you attach everything from mice to printers to your computer quickly and easily. USB was designed to end the headaches of attaching peripherals and worrying about cards, serial ports, parallel ports and card slots. The USB gives you a single, standardized means to connect up to 127 devices to your computer. Connecting a USB device is simple; find the USB connector on your computer and plug the USB connector into it. USB devices are “hot-swappable” which is a fancy tech way of saying you can plug or unplug them with the power on!
USB devices include scanners, mice, digital cameras, modems, zip drives; since most computers have 1-2 USB ports, a power user would purchase a USB hub for multiple devices. USB cables have an “A” side which goes to the computer and a “B” side (smaller) which goes to each device.
from ... www.videoware1.com/videoware/usbport.html
Firewire is Apple Computer’s version of a high performance Serial Bus for connecting devices to your computer. Firewire provides a single plug-and-socket connection that allows you to attach up to 63 devices with data transfer speed up to 400 megabits per second. This high speed of data transfer is particularly good for multimedia applications. With a computer equipped with Firewire, any device (for example, a video camera) can be plugged in while the computer is running. The official name for the interface is Institute of Electrical and Electronics Engineers 1394 High Performance Serial Bus or IEEE 1394. The USB port provides the same plug and play technology and it is less expensive, but the data transfer of USB is 12 Mbps (million bits per second). Firewire provides the bandwidth necessary for audio, imaging, real time video and other streaming data. Firewire allows easy connection to digital audio devices, digital VCRs, digital video cameras, and even digital hard disk drives. With Firewire, the link between a DVC camcorder and the computer is direct, so there is no need for a video capture board.
VIDEO CONFERENCING? Absolutely! The CODEC converts video and audio into digital signals that can be sent via a special phone line to another location. CODEC stands for COmpression/DECompression and can be software that you run or an interface board. The CODEC can even be a hard-wired computer that does just the one task — video-conferencing; see chapter two (“nothing but net”) for pictures and more details!
Finally, we end this chapter with a brief overview of the “computer literacy” of the web and a summary of technological events in the history of computers.5 Each web page is really a “file server” with text and graphics programmed in a language called HTML. When connecting via a modem, your browser software (e.g. Netscape or Internet Explorer) is loading the info from that server. For example, the picture on the right at
www.summercore.com/SBergen.html — is stored on a remote file server at www.valueweb.com in Florida.
The underlying computer program is written in HTML which stands for HyperText Markup Language. The file on the right is a PICT file occupying 64K but before I uploaded it, I changed it to JPEG format to reduce the file size. When you are on the web and click on my web page, this 15K JPEG graphic travels via 1’s and O’s to the RAM chip on your computer! Every page on the web is a file on a server somewhere, perhaps text (html) or perhaps graphics (html). Passwords are needed to upload or change info on these servers, but access for viewing is generally open to anyone.
1918 First Analog computer
1946 First Digital computer (ENIAC)
1955 Optic Fiber
1956 Larry Bird born (12/7/56)
1963 Laserdisc
1965 BASIC computer language
1968 Computer mouse
1968 Computer w/ integrated circuits
1969 Arpanet (prototype of Internet)
1969 Unix computer operating system
1970 Daisy Wheel Printer
1970 Floppy Disk
1971 Dot-Matrix Printer
1972 Compact Disc
1972 Pong (first computer game)
1972 word processor
1975 Ethernet (computer network)
1975 Personal Computer
1976 Ink-jet printer
1977 Apple II computer1977
1 source: Newsweek magazine, winter 97-98, p29
2 source: Time magazine, Dec 97 , p66
3 Silicon Valley is south of San Francisco — towns such as Cupertino, Palo Alto, Menlo Park
4 The Boston Globe, Monday March 16, 1998, page C3.
5 Newsweek Magazine, Winter 1997-98, page 15
Chapter 1 • Hardware • page #