dot-matrix  similar  to  a  dot-matrix  printing  device.  Nor- mally, it is the display device manufacturer who will decide on a specific matrix size—say, 7 by 12 (for a total of 84 dots or pixels) to display each character of text (see figure 1-14). The more pixels used to form charac- ters, the higher is the resolution. Most display devices use  25  rows  of  80-character  lines  when  displaying  text, and there are some that will display 50 rows of 132- character lines in what is called a compressed mode. Graphics   output   consists   of   complex   picture images, which brings us to the term  bit mapping.  Bit mapped graphics use a technique whereby each dot or pixel on the screen can be addressed and individually controlled  by  the  user. This  allows  you  to  create virtually any type of image on the screen. Knowing this should  give  you  abetter  understanding  and  appreciation of why resolution is so important, especially if you are viewing two documents on the screen at the same time, side-by-side,   or   working   with   three-dimensional graphics. The type of monitor or display device you have on your  microcomputer  will  often  dictate  what  type  of display/graphics board you can plug into your system unit.  The  key  word  here  is  compatibility.   Some display devices can automatically switch between any standard  display/color  graphics  card.  Having  such  a display  device  or  monitor  allows  you  to  upgrade  the video/ graphics board in the system unit without having to  upgrade  the  display  unit.  However,  not  all  display devices  are  designed  to  accept  the  different  types  of video   boards   available   primarily   because   of   their resolution characteristics. It is important that you read all the documentation  that comes with your micro to determine whether or NOT your display device will be compatible with the video/graphics board you want to install. Figure 1-14.—The letter “L” as formed within a 7- by 12-dot matrix. Keyboards Of   all   the   components   that   make   up   a microcomputer,  you  will  become  most  familiar  with  the keyboard. It will probably be your primary means for inputting programs and data on microcomputers. Keyboards  come  in  many  shapes  and  sizes,  have different numbers and arrangements of keys, differ in respect to touch, and have special keys to allow you to communicate   specific   software   commands.   Most manufacturers   have   designed   their   keyboards   as separate devices so you can place them wherever it is convenient.  Other  manufacturers  have  designed  their keyboards  into  the  display/monitor  device  or  system unit. The  important  things  you  need  to  know  about keyboards are the types of keys and the function and placement of each. All keyboards have the alphabetic characters (upper and lower case), numbers, and some special characters. In addition, keyboards have special function keys and control keys that are defined by the operating   system   or   the   program.   We   will   briefly describe an example keyboard and explain some of the more common keys you are likely to use. LETTERS,   NUMBERS,   AND   SPECIAL CHARACTER  KEYS.—  The  arrangement  of  letter, number,  and  special  character  keys  may  vary.  The QWERTY keyboard shown in figure 1-15 has the same format as the conventional typewriter. 1-16 Figure  1-15.—QWERTY  keyboard.