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).
Jargon
Pallet A selection of colors from a possible range. Think of it like the paint on
an artist's pallet, but the colors cannot be mixed. If he wants a different
color, not on his pallet, he has to replace one he is not using. There are
several display modes with current graphics adapters supporting 16, 256,
65536 or 16 million colors. Generally more is better, but the eye can
only perceive about 40-70 thousand colors.
Resolution Refers to two things: the clarity and the number of dots appearing on the
screen. Obviously, everyone wants to get more on the screen: as the dots
get smaller, there's less “graininess” in pictures, you can show more on
the display and get more done. However, if you have a small visible area
(typical is 14” or 15” diagonal), the text will get smaller and smaller. A
resolution is usually described with two numbers: number of dots across
the display (x-axis) and the number of dots up and down (y-axis). For
example, 640x480 is 640 possible dots left and right; and 480 possible
dots up and down.
RGB Simply, Red-Green-Blue. The computer mixes these colors to yield all
the visible colors. To see what I am talking about, take a look at “white”
on your color television very closely—you will see the red, green and
blue components.
SVGA “Super VGA“ extends VGA standards to support resolutions up to
1600x1200 and support up to 16 million colors. At this resolution, you
will need a 25” monitor to read the text.
VGA “Video Graphics Adapter” is a standard which supports minimally
640x480 with 16 colors.
There are two parts of the display: the monitor (the viewable device) and the graphics
card. They are usually interdependent. If you want SVGA, you will need to get an
SVGA card and a monitor to support it. Unless you are 100% comfortable with finding
compatibilities, always buy a monitor with a new card. Of course as with everything else,
the price of displays has dropped dramatically. This will continue as new standards are
introduced and companies continue to compete for market share.
1.2.2.1Monitor Operation
How do they work? The computer reserves a section of memory (video memory) to store
the color and intensity of each dot. This information gets sent to the monitor 60-70 times
per second (called the “refresh rate”). The monitor takes this information and, using three
beams of electrons (red, green and blue) excites the phosphor inside the tube. The higher
the number for a particular color, the more electrons get sent to that dot, the brighter the
color. Please note that there’s no such thing as a “green electron”. The inner lining of the
tube has has thousands (millions?) of individual red, green and blue dots. And, the three
electron “guns” point to their assigned dots.
Older monitors expected a specific rate of incoming data. So, if you tried to display
1024x768 on an old monitor, you may not see anything at all (since they were 640x480 or
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 dayout,
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 (millionbytes),
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.
Table 1: Modern and Historical Computer Storage Media
Media Description Cost ($/MB) Permanence Life Capacity Access2
Card Ancient paper storage (???) Write-once 5-10 years 80 bytes Sequential
Paper Tape Ancient paper storage (???) Write-once 5-10 years (???) Sequential
Floppy Magnetic material on flexible plastic disks .10-.20 Read/writable 2-4 years 1-00MB Random
Disk Magnetic material on metal disks .25-.35 Read/writable 3-6 years 10-9000MB Random
Tape Magnetic material on flexible plastic tape .01-.05 Read/writable 2-3 years (???) Sequential
CD-ROM Laser-technology .00002 Write-once3 (indefinite) 650MB Random
DVD Digital Video Disk (like CD-ROM) (???) Write-once (indefinite) 6-12GB Random
RAM Computer chip memory 10.00 Only while
powered
10-20 years 1-64MB Random
ROM Computer chip memory 50.00 Unwritable 10-20 years 1-4MB Random
2 Access refers to how the data is retrieved. Sequential means that the computer has to start at the beginning and search until found (like trying to find your
recorded show on a rewound VCR tape). Random means that the computer can skip directly to the starting point of the data (like a card catalog).
3 Not likely writable at all. Most of the time, these are already filled when delivered. There are versions that can store data, but the tools are very expensive.
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 210
M (mega, million) in computerese 1,048,576 or 220
G (giga, billion) in computerese 1,073,741,824 or 230
T (tera, trillion) in computerese 1,099,511,627,776 or 240
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 computergenerated
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