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Computer Fundamentals
Notes about this manual:
It was my intent to make this useful and easy to use by everyone —yes, even from those who have used a computer to those who have never touched one. Please note that it was written for those who have never touched a computer. Organization. This text tries to build on itself. I was very concerned about “overload” (too much information which leads to frustration) and even “underload” (too little—which leads to confusion). Everything in the textual parts which are not flagged as “Advanced” or “Expert” are important to understand why the computer does certain things and why it can’t do other things. Please be patient and read through all of it. It is also intended to be a reference once you’re done with the course. So, there are several Tables and Indices at the end of the text. Notation. You may see some interesting notations in this text. To help you, this notation tries to be consistent with computer manuals. For example, you may see . This means (and all other angle-bracketed notes) a particular key on the keyboard (in this case, it means the Enter key to the right of the alphabetic keys). If you see <Ctrl-F> or <Alt-F4>, that means holding the , or key then pressing the other key (e.g. <Ctrl-F4> means pressing the key while holding the key). Also, Edit|Cut means “under menu ‘Edit’ select option ‘Cut’.” Suggestions. Suggestions are always welcome. I didn’t design this course for me but for you. If there is anything that I can do to help you work with computers, please let me know.
1 HARDWARE: “WHAT DO I NEED TO KNOW TO BUY A COMPUTER?”
What is a computer? I guess the easiest way I can explain it is as a little machine that follows very specific instructions over and over. A computer cannot learn and, unless told to do so, won’t respond to anything. Think of it as a very dumb dog that you have to teach to catch a ball every day and every time you want to play.^1 Computers do very complex math. Mind you, it is always related to the basics: add, subtract, multiply and divide. But as anyone who has had algebra and calculus will tell you: if you do enough of these basics, you can get approximations of more sophisticated math that are pretty close to reality. Computers do this math very quickly. Often these calculations are done in millions per second. Imagine multiplying 10 million pairs of multi-digit numbers per second. I have a hard enough time myself doing a 3-digit multiplication in less than a minute. Computers can store a vast amount of information and retrieve it at extraordinary speeds. When everything works correctly, this data is as fresh and unblemished by time as when it was first stored. It can record information about everything (given it has sufficient storage capacity). While this may not seem to be a great achievement, think about this: when you last went to the store, how much did you pay for each item you bought? Computers can store this kind of information a lot better than we can recall it. Also, one of those CD-ROMs that we see so frequently can store the entire Encyclopedia Brittanica along with photos. (Please note that if you buy their CD-ROM set, it has more than just text and photos. So, the set has several CD-ROMs.) What have computers done for us? Consider the following:
- Made the world incredibly smaller by facilitating communications.
- Advanced science and medical discovery more in 10 years than in centuries of history.
- Designed cars, roads, cities, clothing, etc.
- Tested transportation long before the prototypes ever left their studios.
- Exploded our imaginations with color and virtual reality.
- Controlled our market-place and caused the “Black Monday” crash.
- Hinted that a passenger aircraft over Saudi Arabia was an enemy and recommended firing on it.
- Opened freedom of speech to areas all over the world via the Internet.
- Abetted fraud, laundering and gambling.
(^1) Today (12/4/96), I read plans to make machines “more intelligent”. A quote from Bill Gates, Microsoft CEO: “If a human assistant works for you over a period of years, your efficiency in working with him gets dramatically better and he can anticipate your interests and you can use shorthand ways of communicating. With a computer today, even if you use it for a couple of years, you are basically working with it the exact same way. It's not learning in the way a human assistant would. On the simplest level, the next generation of computers would learn the kind of information you like to see. They're going to know how you are reacting to things, and essentially put together, for example, the kind of newspaper that meets your interests.” (Investor's Business Daily 3 Dec 96 A8)
1.1WHAT PIECES ARE FOUND IN A COMPUTER?
Jargon
Term Definition
Adapter Most of the time it refers to a card that plugs into the motherboard adding special capabilities not originally found on the computer. Other times it refers to tools to convert one connector type to another. Cables A thick wire that connects the computer to the external device or power. Cache An interface between the CPU and the memory (RAM and ROM). It helps the CPU keep running even though the RAM may be too slow. It does this by keeping a copy of what the processor has read/written. Card Slot The slots found on the PC motherboard may be one of five types: ISA, EISA, MCA, VESA & PCI.. Slower adapters (like I/O boards) can be ISA. But for the best performance, use VESA or PCI for harddrives, CD-ROMs or Video adapters. Cards An option (adapter) which is a printed circuit board that plugs into the motherboard. CD-ROM A disk made of plastic and aluminum which can store up to 650MB of data. Usually these disks cannot be written to, instead they often are used to distribute software from companies. CPU Central Processing Unit. The “brain” of the computer. It executes commands which, eventually, we see as a response to our input. Without the CPU, the computer is nothing. Disk A storage medium to keep data while the computer is turned off. DRAM RAM that uses a device called a “capacitor” to store each bit. The problem with this is the capacitor loses the charge very quickly. Therefore, the DRAM has to be “refreshed” to keep the data valid. This is thus far the cheapest RAM. DVD The next generation CD-ROM which will store 10-20x the current capacity. Floppy A disk that has flexible media (the actual material onto which the data is recorded). The material and flexibility is a lot like that of a cassette tape. Glidepoint A mouse-replacement that has a little pad that you can use to move the mouse pointer. Simply glide your finger over the surface and the pointer will move. To “click”, tap the pad. To “double-click” double-tap the pad. Harddisk A medium to store data for the computer while the power is out. It uses a hard material (typically aluminum). Keyboard A typewriter-like tool that has keys. Sends letters or commands to the computer. Micro- processor A CPU that composes only one chip. Some CPUs may actually be several square feet is size; but, the microprocessor is designed to be 100% self-contained in a single chip. Modem A device that will let your computer talk to other computers through the telephone line.
Jargon Monitor The CRT or display that shows the words, graphics, etc., to the user. It is a critical part of a user’s interface. Motherboard A printed circuit board that has (at least) slots to connect cards into. Often, they also include a CPU and memory. Mouse An input device which has one to three buttons and when you move it, it causes the arrow in a Windows display to move. Open Architecture The original computer companies hid their secrets from competitors by keeping their architecture closed (proprietary). IBM made the IBM PC an open architecture, allowing anyone to make options for it. Parallel A type of port which transmits and receives several bits of data at a time (typically 8 bits). Typically used to connect to printers. Ports Connectors (usually in the back of the computer) which connect to external devices (e.g. mouse, keyboard, modem, printer, display, etc.) Power supply A basic component in the computer that converts the outlet power into power that the computer can use. Printer An external device that takes commands and data from the computer to place on paper. There are several types of printers: daisy-wheel, matrix, laser, thermal, inkjet, and plotter. RAM “Random Access Memory“. A pool of storage for the CPU. It can be written to/read from in any order (unlike a VCR tape which is serial— you have to wind to the place you want). There are several types of RAM: SRAM, DRAM, EDO-RAM. ROM “Read Only Memory“. Memory that has imprinted in it data and programs for the CPU which cannot be erased or written to. Scanner An external device that is able to optically read in printed material—kind of like a copier, but it stores the image on the computer instead. Serial A type of port that transmits only one bit at a time. In order to send a byte of data, the data has to be “turned on its side” and send out bit by bit. SRAM RAM that does not “lose its mind” if not refreshed. This is typically used in caches. It tends to be much more complicated than DRAM and thus much more costly. Surge protector A device that will isolate your computer from outlet power problems (spikes and noise). Trackball A mouse replacement that is a small box with a ball in the center. You roll the ball in the direction you want the pointer to go. Trackpoint A mouse replacement with a little rubber post between the “g” and “h” keys on some laptop computers. Gently push the post in the direction you want the mouse pointer to go. UPS “Uninterruptable Power Supply”. This is a box that is like a surge protector but will keep you going even if you lose power. You can plug your computer into. If you have a brown- or black-out, this unit will keep you running for 3 minutes to an hour (certainly enough time to save your work and shutdown the computer).
1.2PERSONAL COMPUTER HISTORY
In order to properly understand and appreciate the progress we have made and to anticipate the continued evolution of the industry, let's look at the progress of the computer. What precisely is a computer? Machines that helped people do computation have been around for almost 150 years (Brigham Young invented a device to calculate the number of miles a wagon traveled by counting the number of wheel rotations). There have been all types of machines built to compute or measure various things (there’s even one that will compute a logarithm). Most of these machines are “analog” or value-based. So they can represent any value between zero to one equally as well as zero to a million. An example of an analog device is the odometer on your car (please note that these may not be true analog, but the concept still holds). Whether you move the car one inch vs. one thousand miles, it makes little difference—your car still retains the distance, thus further depreciating it’s value. There was another type of machine which used a magnet-powered switch which would close the switch when the electromagnet was turned on (this kind of switch is a “relay”). Telegraph used crude relays. The advantage of using switches (either “on” or “off”— called “digital”), the results would always be predictable (the value will always be zero or one). Analog devices always have to be tuned (just try to put a different sized tire on your car). The problem with relays is the power required and delay experienced was too great to make them into a computational device. Early computers went a different route by using electron (or vacuum) tubes. Vacuum tubes have been used for power amplifiers, but they could also be used as switches as well and would function many times faster than the relays would. The idea was pretty simple: the tube had three plates. The first plate was the source power, the second was the destination, and the third was the “switch.” The electrons would at the source would gather but would not be able to get to the destination unless power was applied to the “switch-plate.” Think of it like having scuffed your feet on the floor to generate static electricity then getting close to something (or someone) you want to zap— still they’re too far away. You need something to close the gap. That’s something like what the “switch plate” does. Memories and calculations were held and completed by turning on and off thousands of these switches. However, vacuum tubes still required tons of equipment and megawatts of power. The proverbial add/subtract/multiply/divide calculator on your wrist used to take up an entire building floor and require many megawatts. In the mid 1950s, a special little switch was invented that has thus reshaped our history: the transistor. The power (no pun, honestly!) in this little thing was it’s size (less than. 1”—compared to 3-4” for a vacuum tube) and its power (much less than a watt— compared to 5-10 watts).
Modern computers are composed of millions and millions of these transistors switches. Like the vacuum tubes, the transistors are arranged in arrays to accomplish what we ask of them. Your computer memory alone has millions of transistors—one megabyte has one million bytes or eight million bits. That’s more than 8,000,000 transistors! Personal computers have been around as early as the mid-1970s. The companies involved include Apple, Commodore, Atari, Synclair, to name a few. The first chips for these computers only had 10-50 thousand transistors. At the time personal computers were not taken seriously and were infrequently found in the workplace. The first attempt to make a business-directed personal computer was by Apple when they introduced the Lisa computer. That was a failure—mostly do due to the $7000 price tag. The next was the Macintosh which was better received. The growth of personal computers did not really take off until IBM entered the market. From their open architecture, hundreds and thousands of computer companies sprang up. All the while technology advanced at a tremendous rate. Also, due to advances in chip manufacturing, the prices plummeted.
1.2.1MICROPROCESSOR REVOLUTION/EVOLUTION
The microprocessor, from the onset of personal computers, has been the driving force of hardware and software technology. There a couple primary claims to the first microprocessor, but the concept of placing all the computing power on a single literally was revolutionary. In fact, many of the first microprocessors (as old as 25 years!) are still being manufactured and used as simple control units in various appliances and machines. As the processor became more powerful, the supporting hardware and software became more powerful and complex. Simply, a processor takes commands from memory and does things with them. Think of it like your math teacher telling you each step to solve a problem. These steps are repeated over and over—the computer does not learn, rather has to follow each command issued to it the same as the day before. Here we need to clarify a few things: processor families and clock speeds.
1.2.1.1Processor Families
Think of some kind of blender in the kitchen. It originally had a dial to select the speed: either blend or liquefy; then, a new model of the same blender came out with buttons. Now, the modern model has “flash” or “chop” modes that only run while you are holding the button. These extra capabilities which may not seem all that significant are called “features.” The sequence of blenders from the original design is called a “product family.” Microprocessors have these families as well—in fact, they are far more crucial to the industry than that of the blenders'. Because software was written for an old processor, the industry does not want to rewrite the software for the new one. This is called “backwards compatibility.”
1.2.1.2Clock Speeds
The clock is like the rhythm to a song: each word is sung to each beat; the faster the beat, the faster we can complete the song. Generally, the processor obeys (called “executes”)
Lastly, processor prices have continued to drop. To fully appreciate this, consider: when the Pentium/60 (60MHz version of the Pentium) was introduced to the market it retailed for about $800 per chip. Now (if you can find them), they are less than $50 per chip. So getting the “latest and greatest” does not always make sense. Sometimes—no—often, one- to two-year old technology is the best priced, most reasonable and all that we really need [this is my opinion, of course]. Advanced : The instructions used on a processor are called “opcodes” (short for “operation codes”). These opcodes interact with the processor’s registers, temporary storage locations for intermediate results. At nearly every clock time, the processor places an address on the address bus. The memory responds by placing data on the data bus. You may have learned something about 16-bit or 32-bit processors. The bit size refers to the native register size of the processor. If there is a discrepancy, it then refers to the largest data word size. The 8086 was a 16-bit processor—each data chunk was 16-bits — (even though it could address 20-bits of address space). The 8088 (a sister to the
- is still 16-bit even though it gets 8-bits of data at a time. This is called a 8/16-bit processor (which means internally it’s 16-bit but it grabs 8-bits at a time). In the Intel processor line, a 80386DX is a true 32-bit processor (the first in the family). But Intel created the 80386SX which was 16/32-bit processor. The next processor, 80486, was the first in the product family to include the floating point processor. But, then they had to muddy the water a little with the 80486SX which was a true 32-bit processor without the floating point processor. Go figure. The Pentium had a nasty little floating point bug which Intel has fixed. In a nutshell, part of the needed data in the processor was not included with the chip (forgetful, I guess). When a special condition occurs (which happens pretty frequently), your 17- digit number becomes a 7-digit number. The Pentium Pro’s design expected that 16-bit programming would have been dropped by now. Well, they were wrong. So that’s why your old DOS and Windows programs may actually run slower than a Pentium. To accelerate support for this new chip, Microsoft is forcing all programmers to use the new 32-bit programming style. If you see the Windows 95 logo on the package, you can be sure that it will not stall on your Pentium Pro.
1.2.2DISPLAYS
Displays are CRTs (cathode-ray tubes—the same technology as most television sets). When the first personal computers came out, the monochrome (a green-lettered or black and white display) was what you typically got. Graphics were expensive and color was much worse. The first color display I used could only show 4 colors at a time and these were very “user-hostile” (like “lime-green”, “orange-red”, “dull-yellow” and black—yes, black is a color in computers). First a few more pieces of jargon: Jargon
Term Definition
Dots/Pixels The smallest changeable point on the screen. A dot can have any color from the palette. Expert : There are about five different types of processors:
- CISC (Complex Instruction Set Computer). A classic CISC will have all instructions built into ROM’ed microcode and that takes several clock cycles to execute. They have up to two thirds unused instructions by standard processors. Because of their complexity, they require 4x the number of transistors to do the same processing as RISC. They generate more heat, require more power, and tend to be slower than RISC at the same clock speed.
- RISC (Reduced Instruction Set Computer). A classic RISC hard-wires every instruction and only has instructions typically used by compilers. Also more complex instructions (like “divide”) are split into at least two opcodes. Most of the time, programs converted from CISC to RISC will grow by about 33%. Nevertheless, they are still faster, cooler and cheaper to make than equivalent CISC.
- Microcontroller. This is a specialized microprocessor that does specialized operations. For example, most calculators or alarm systems use microcontrollers.
- Vector Processor. These are very fast processors that parallelize processing so that many actions can be accomplished at the same time. The use of these processors have diminished with the introduction of more powerful RISC/CISC processors.
- Bit Slice. These are archaic, linkable processors. Each processor would work on a certain number of bits (e.g. a 4-bit processor). With the addition of each processor, the computation word gets bigger (e.g. 5 4-bit processors can work with a 20-bit word).
800x600 only). A “multisync monitor”, on the other hand, automatically senses the frequency and adapts to display it. So, if you heard a “click” or some other strange noise when you switch from plain text to graphics, don’t worry: it’s likely just adusting to meet your needs. (However, if you hear this sound again and again or the monitor acts erratically, quickly reboot or turn off your computer!)
1.2.2.2Health Concerns
Some have wondered about being so close to a monitor and being exposed to radiation. In truth, CRTs use a stream of electrons to excite the colored phosphor causing it to glow. The original CRTs emitted other radiation that included X-rays. Modern monitors have much less radiation and have to comply with very strict government regulations. Still there are other health risks that are still being researched. Monitors and power supplies use very powerful magnets and electric fields: both of which have been suspect of cancer. A minor problem is the eyes. If you stare at something closely day-in and day- out, your eye sight will degrade—ask any opthamalogist. If you get headaches after working with a computer for a while, consider changing ambient light, getting a larger display, increase the distance between your eyes and the display, increase the display font size (bigger type), or follow the “advanced” section, below.
1.2.3STORAGE LEAPS
Every letter of a document and every dot on a picture requires a place to store it. There are several kinds of storage, and there are many storage media. Each has its advantages and disadvantages. Often media are compared with four criteria: cost/MB (million- bytes), permanence, capacity, access and life. Advanced : The clarity in a monitor is the “dot pitch” or the size of the controllable dot size (.31 is the worst, .28 typical and .26 is the best). The larger the dot, the more unclear the display will be. Most of the time, the smaller dot sizes will be more expensive. However, if you know you have a good dot pitch, you may have problems with a faulty adapter. Also, if you see flicker from the screen it may be caused by either of two things. The first may be caused by interference caused by florescent tubes which blink at 30Hz. If this is the case (and you have florescent tubes), try a different refresh rate (like 72Hz). If this doesn’t solve the problem, look carefully at single horizontal lines (you may have to look away by about 10-20°). If the line looks like it’s jumping up and down, then you are in interlace mode (mega-nasty to the eyes). Try a lower resolution or different drivers.
Advanced : I only mentioned a couple harddisk formats (EIDE and SCSI). There are (as you might expect) so many different formats that I can’t even numerate them. All the rest really are not that important. However, if you get the misfortune of getting one of the older kinds (they are very slow and small capacity), you can probably find adapters for them. But you may have trouble finding drivers for them. The older standard of EIDE (IDE) had troubles maintaining speeds comparable to SCSI and it’s capacity was locked in at no more than 540MB. Again if you have an older computer (like pre-1989), you may have trouble adding the new EIDE drives without special drivers. Fortunately, most EIDE drives include these drivers.
1.2.4MEMORY DUMPS
One thing that is certain: memory is a crucial part of getting performance (maximum processor speed) from your system. Everyone wants more memory; and every memory chip manufacturer wants to increase or control market share. Several companies (typically foreign) have resorted in “memory dumping”—selling memory below the actual cost of manufacture. This does three things: 1) makes memory cheaper so that we can “soup-up” our computers, 2) forces other memory prices down, and 3) kills competitors who can't compete. Memory prices, in general, have dropped incredibly fast. Even the predictions have been considered conservative compared to the actual trend. As of Sept. 1996, one could buy memory for as low as $5/MB. Naturally, this will likely fluctuate wildly. The best time to buy memory is middle to late summer. Don't buy memory Oct. to Jan: these are the worst months due to the holiday seasons. Advanced : There are several things you need to be aware of before buying memory. First, you can’t go wrong with faster RAM (rated in nanoseconds—lower numbers are better). You can have big problems if you get too slow RAM. A good rule of thumb is Pentium/90 and less can use 70ns RAM, but any faster processor should use 60ns RAM or less. Parity RAM vs. non-parity has long been a heated discussion. I’ll leave this up to you: DOS and Windows will halt the processor if you get a RAM parity error. Non-parity will not generate this error. So, I ask if you have an error and crash by the error or the halt, what difference does it make? EDO RAM only gains a 3-10% performance increase on the average but costs 10% more. Expert : Cache RAM is typically 256KB. But due the way the 80486 and Pentium cache the ram, you will have problems when you increase your RAM to 64MB. In order to use 64MB of RAM on these systems, you will need to replace your cache RAM to 512KB. The Pentium Pro incorporates the cache on the chip, and there are some that have only 256KB cache RAM. I have asked on the Internet and have been assured that the problem with the caching algorithm was fixed making 256KB sufficient for 64MB.
1.3WHAT DO I NEED?
Jargon
Term Definition
Kb, KB Mb, MB Gb, GB Tb, TB Mostly, they have the same meaning as the normal scientific prefixes, but computer people had to change things slightly. Here is what the individual letters mean: K (kilo, thousand) in computerese it means 1024 or 2^10 M (mega, million) in computerese 1,048,576 or 2^20 G (giga, billion) in computerese 1,073,741,824 or 2^30 T (tera, trillion) in computerese 1,099,511,627,776 or 2^40 b bit, the smallest unit of storage either has a value of zero or one B byte, a group of 8 bits. Since each bit can be zero or one, a byte can have a range of 0 [0000,0000] to 255 [1111,1111]. Typically, a letter on the keyboard is stored in a byte. With that behind us: Kb (kilobit) one thousand bits KB (kilobyte) one thousand bytes [often referred to as “K”] Mb (megabit) one million bits MB (megabyte) one million bytes [often referred to as “meg”] Gb (gigabit) one billion bits GB (gigabyte) one billion bytes [often referred to as “gig”] Tb (terabit) one trillion bits TB (terabyte) one trillion bytes VR “Virtual Reality“. A simulated 3D world in which you can move around and interact with things. The movie “Toy Story” is a computer- generated VR environment. Often, I am asked: “I want to buy a computer. What should I get?” Talk about a loaded question. It's like my wife asking, while turning her head fashionably looking at new hats, “Which do you like, dear?”. Klaxons go off; people scurry for the nearest exit; our dog cowers and hides its head. While I simply (blithely?) blunder into the “danger-zone” by answering based on the price tag. For all the advice I have given to people about what they should get—this advice has never been heeded. Oh, well. There honestly is no “right” or “wrong” choice: it's really the difference between what you want vs. what you are willing to pay.^4 (^4) I need to amend this slightly. The truth is: you will pay either now or later. There are some companies that should absolutely be avoided at all costs. Otherwise, you will either be paying for fixes that would never have been necessary, have a lot of “down-time” (no computer work being done due to a broken computer), or have incessant support line calls (which most of the time they’re busy or on infinite hold), because “this, that or the other thing” doesn’t work very well. I won’t list the bad-guys, instead I would
