Hardware and Software
|2-1 Hardware vs. Software|
|2-2-2 Inside the Box: The CPU!|
Before looking at computers it is essential to understand that they are composed of two very distinct parts: hardware and software. Hardware is the physical, machine components of the computer -- the monitor, the keyboard, the chips, etc. Software is the programs that run on the computer, like MS Word or ArcView.
A good analogy is a stereo. Hardware is like the components of a stereo: the
tuner, tape drive or speakers, while software is similar to the tapes, records
or CDs that you play on it. Although your music and your stereo system work
together (your CD's sound better on a better system) they are also independent
(you can change your speakers without effecting the content of the CDs
2-2 Hardware :
The Main Keys (a,b,c,...): on the keyboard behave like a standard typewriter.
Modifier Keys (Ctrl, Alt): These keys have specific functions in software programs when used in combination with the letter keys. For example, to do Ctrl 'A' you would hold down the modifier key Ctrl and tap the A key once. In general, the Ctrl key on a PC = the Command key on a Mac; the Alt key on a PC = the Option key on a Mac. Macintosh's also have a third Modifier key: Control.
Function Keys: These include the Esc and F1 through F12 keys at the top of the keyboard, as well as the Home, Help, End, Del, Page Up & Down keys located above the arrow keys. Their functions are different depending on the software program that you are running. They can sometimes be programmed.
Arrow Keys: Located in between the number pad and the main keys, the arrows let you move around in most programs.
Number Pad: If the NumLock is on (turn on/off with button in upper left-hand corner of number pad), the number keys give numbers. If it is off, the keys act like the arrow keys (8 is up, 2 is down, etc.).
Indicator Lights: Located above the number pad, they tell you if the NumLock or Caps Lock are on.
The mouse lets you point to things on the screen. Often, you can use the mouse to select objects, drag them from one location to another, or to draw lines and shapes (CAD and graphic design programs).
3. Digitizing Tablet:
The digitizer uses a magnetic field to pinpoint the exact location of the tablet cursor (the digitizer's 'mouse') on the board. If you spread a base map onto the digitizer you can quickly and accurately enter coordinates, contour lines, etc. into a GIS
ERGONOMICS!!! Repetitive Stress Injuries (RSI)
are injuries which occur through the repetition of a seemingly harmless
movement, like typing or clicking a mouse. As a computer user, you run the risk
of contracting RSI's.
2-2-2 Inside the Box: the CPU!
Figure 2-2 Diagram of the CPU
1. The MotherBoard:
This is a large printed circuit board that holds most of the main electronic parts, including the chips.
a) The Processor The processor, or chip, is the engine of the computer, processing information given to it by whatever program is currently running. The speed and power of the central processor to a great extent determines the speed and functioning of the computer. This is why most computers are referred to by their chip.
PC chips are, from slowest to fastest: 486, Pentium and Pentium Pro. For CAD or graphics (such as in ArcView), a Pentium chip is the absolute slowest that you should consider. The equivalent of the Pentium for the Macintosh is the PowerMac chip.
The speed of chips is rated in Mhz: a 200 Mhz chip is much faster than a 90 Mhz chip. Only chips of the same type can be compared this way, though. A 90 Mhz Pentium chip is still much faster than a 120 Mhz 486 chip.
b) ROM Read Only Memory is also located on the MotherBoard. It holds specific instructions for the computer. Unlike all other types of memory on the computer, this memory cannot be altered after it leaves the factory.
2. How the Computer Stores Information :
The smallest unit of memory is a bit. It can be only two things: 0 or 1.
The standard unit of memory is a byte. It is 8 bits.
To give you a sense of scale:
|15 K||all the text on this page|
|100 K||a very small text file|
|300 K||a small Data file|
|1 M||a low resolution image file|
|1.4 M||a floppy disk|
|10 M||a high resolution, 8.5 x 11, image file|
|650 M||a CD ROM|
|2+ G||a typical Hard Disk in 1998|
• Binary vs.
ASCII File Types:
Files are generally one of two types: Binary or ASCII. Bytes (8 Bits) are the standard unit of measurement. In a Binary File, 1 Byte contains 1 Number. In an ASCII file, 1 Byte contains 1 letter of text. Binary files are therefore filled with numbers, while ASCII files are filled with text.
Text files are saved by the computer as ASCII files. Just about everything else (graphics, CAD, spreadsheets, etc.) are saved as binary files.
• 8 Bit vs. 16
As we said before, 1 byte (8 bits) is the standard unit of measurement. The more bytes that a processor can read at once, therefore, the faster it can work. For example, often 1 byte is not enough to define a number -- 2 or 4 bytes may be required. If the processor can read all of the 2 or 4 bytes simultaneously, it can work much faster than one that has to read the bytes one at a time. 16 bit (2 byte) processors are therefore more powerful than 8 bit processors, 32 bit faster than 16 bit, etc.
3.Information Storage Devices :
Memory is different from disk storage. Memory refers to random access memory (or RAM), while disk storage refers to permanent, magnetic or optical memory devices like CD ROMs, floppy disks, or hard drives.
RAM is memory that is used by the computer to hold programs that are currently running. When you start a program it does not appear immediately -- the computer pauses while it whirs and clicks at you before letting you into the program itself. During this time it is copying the program from the Hard Drive into RAM. RAM, unlike the Hard Drive, is electronic memory - it is erased every time you turn off the computer. The advantage of RAM is that it is about 100 times faster to read from it than it is to read from the hard drive. The computer therefore loads programs into RAM so that it can run faster.
A good analogy of RAM is a drafting table. If you have a small table, there is a limit to the number of things that you can do at once. Projects requiring big sheets of paper may even be impossible. RAM is the computer's drafting table. If you only have a little RAM, the computer can only use small programs or can only open small designs. As the amount of RAM that is loaded into your computer grows, so too does the number and size of different programs that can run simultaneously.
Storage space is different from RAM in that it is more permanent and you can control precisely what goes into it. It is generally either magnetic (disks, hard drives) or optical (CD ROMs).
Hard Drive: This is a fixed storage device located inside the CPU of all computers. It is not meant to be removed, and can hold a significant amount of information (usually between 500 MB and 8 GB or gigabytes).
Floppy Disks: are the smallest types of storage devices. Always buy double-sided high density disks - these hold 1.44 Megabytes of information, the maximum possible in a floppy. When you buy a floppy disk you usually have to format it first. Be careful handling them -- do not touch the inside surface, be careful to keep them dust free, and NEVER BRING THEM NEAR A MAGNET because that will ERASE them!!!
CD ROMs: employ a different method of encoding information -- a laser inside of the CD ROM drive 'reads' a microscopic pattern of 0's and 1's etched into the disk's surface. CD ROM's contain far more information than floppy disks (around 650 Meg's) but you can generally not write to them (i.e., you can't save information onto them, only read information burned onto the CD by whoever created it).
Tapes: Tapes come in all forms and sizes. Some computers come equipped with a tape drive that allows you to read and write to them. Tapes can contain from 80 Megs to 1 Gig.
Zip / Syquest: Other types of memory storage devices have come into the market. Both Zip and Syquest as popular examples. They employ a separate drive that plugs into your computer. Their disks can hold from 100 to 500 + Megs. Some of the machines in this lab are equiped with Zip drives. And sometimes they work.
The Monitor creates an image by using a beam of electrons to scan an image onto the thousands / millions of tiny dots (pixels) that make up your screen. This method of creating an image out of tiny dots is called raster. The speed with which the beam of electrons scans an image onto the screen per second is called the refresh rate. If the image seems to flicker, the refresh rate should be higher. The number of pixels that make up your screen is called the resolution. The higher the resolution, the greater the number of individual dots that make up the screen, and the finer or more detailed the image. Different monitors can also support a different number of colors. A monitor in 8 bit mode can use 256 colors. 16 bit mode allows for a much greater number of colors (256 x 256) and is especially useful for displaying images. 24 and 32 bit modes are also possible, but require special graphics cards and lots of memory!
2.Printing Factors to consider:
Resolution: For text this is not very important, but for pictures or graphics it is extremely important. 600 dots per inch (dpi) is considered high resolution, 300 dpi medium, and below that low (there are exceptions depending on the printer).
Paper: Standard printers can handle only 8.5 x 11 or 8.5 x 14 paper. Paper is placed in a paper tray at the bottom of the printer. To add a single sheet of special paper (like resume paper) there is generally a paper-feed that allows you to bypass the main tray. To print on a larger piece of paper, use a plotter. The HP650C in room 330 uses pens to print on paper up to 4' wide.
2-3 Software :
These are complicated programs that provide the link between the programs that you are using (Word, MicroStation) and the computer Hardware.
Software is the programs which you run on your computer. The following is a brief list of some of the major types of software available, and those programs which we have here in the Geography Lab.
Word Processors: These programs create text documents (papers, letters, etc.) Microsoft Word is the program installed on the PCs in this lab. PCs also have a more limited program called NotePad, and Macs have a more limited program called SimpleText.
Spreadsheets and Databases: allow you to manage large amounts of data, and to create charts and tables. Microsoft Excel is a good example.
Graphics: These programs allow you to manipulate images. For example, you can 'scan' in an image, play around with it on the screen, and then print it out. Adobe Photoshop works in Raster (divides the picture into pixels) and is generally best for image manipulation. Adobe Illustrator works in vector (draws real lines) and is best for drawing lines or text. Adobe FreeHand is a bit of a mix of both of these methods and of Desktop Publishing.
Desktop Publishing: These programs allow you to mix images with text and to place them attractively on the page. They are far more versatile than Word Processing programs but are less good at doing simple things like papers or long documents. Quark Xpress, and Adobe PageMaker are examples.
Computer Aided Design: Programs which allow you to draw and render complex landscape or architectural designs. Good CAD programs allow you to work in three dimensions as well as two. Examples include MicroStation, AutoCad, MiniCad, ArchiCad. Many of these programs (especially Microstation and AutoCad) can be used to enter data into a GIS.