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Chapter 1: CADD Hardware and Software


About this Chapter
Key Terms in this Chapter
Hardware and Software Overview
CADD Hardware
  • System Unit
  • Central Processing Unit (CPU)
  • Memory
  • Hard Disk, Floppy Disk, CD-ROM
  • External Storage Devices
  • The Monitor
  • Printers and Plotters
  • Digitizer, Puck and Mouse
A Typical CADD Network

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CADD Software
  • Draw
  • Edit
  • Data Output
  • Data Storage and Management
  • System Control
  • Special Features
CADD User Interface
  • Using the CADD Menus
  • Entering Commands in the Command Window
  • Using the Tool Buttons
  • Using the Dialog Boxes
  • Working in the Drawing Window
About this Chapter 
This chapter provides a general overview of CADD hardware and software. There are three main topics in this chapter:
  • CADD Hardware
  • CADD Software
  • CADD User Interface
CADD Hardware describes the physical components of a CADD system such as system unit, memory and hard disk. It introduces the requirements and specifications necessary for CADD equipment. Note: If you are familiar with computers, you may want to browse through the CADD Hardware topic to re-familiarize yourself with information referred to in later chapters. If you are unfamiliar with computers, you should read the entire topic before proceeding.   CADD Software describes the main functions of a CADD program, such as drawing, editing, data output, system control, data storage and management and other special features.

CADD User Interface describes how to interact with CADD by various means of data entry. You will learn how commands are entered using the menus, keyboard, toolbars, etc.

Key Terms in this Chapter
Bit, byte,

megabyte (MB),

gigabyte (GB)

A bit is the smallest unit of electronic memory. The second smallest unit of memory is a byte, which contains 8 bits. One megabyte contains one million bytes. 1000 megabytes make one gigabyte.
Data exchange format (DXF) A standard format used to exchange electronic drawings between different CADD programs.
Digitizer An electronic data input device.
Dots per inch (dpi) A specification of printers and plotters that determines how accurately they can print.
Dot-pitch The distance between the picture elements (pixels) on the screen.
Graphical user interface (GUI) An environment established by the program that uses graphic clues to help the user communicate with the computer.
Hardware The physical components of a computer.
Mainframe system  Large computer that processes data at very fast speeds and has a lot of memory. Used by large organizations.
Megahertz (MHz) The speed of data processing. The speed of one million cycles per second is called 1 MHz.
Minicomputer Smaller version of the mainframe system. Also used by large organizations.
PC Personal computer, also know as a microcomputer.
Resolution The sharpness of the image on the screen.
Server A computer dedicated to running the network program, with computers connected via a network.
Software The programs that run on the computer.

Hardware and Software Overview AutoCAD Forum

There are two parts of a computer system, hardware and software, and a CADD system is no exception. Computer hardware is the physical components of the computer such as system unit, monitor and plotter. Computer software is the program that determines the application of a system.

There are three main categories of computers with respect to hardware:

  • Mainframe
  • Minicomputer
  • Microcomputers, for example personal computers (PCs)
Mainframe computers have a lot of data processing power and their size is quite big. A single mainframe computer performs all the data processing and is accessed via terminals connected to it. Minicomputers are smaller versions of mainframe computers. Microcomputers (PCs) are the desktop or laptop computers of today and are used for individual computing needs.

There are two main categories of computer software:

  • System software
  • Application program
The system software manages the internal operations of the computer. An important part of the system software is called the operating system (OS). The operating system acts as a platform to run application programs such as CADD. It is also used to manage the electronic files in the computer. There are a number of operating systems available for different categories of computers; the following are notable to mention:
Operating System
Microsoft Windows

(Windows 95, NT, 98)

The leading operating system of today commonly used in Intel and IBM-based PCs
MS DOS, PC DOS The popular operating system of the last decade commonly used in IBM and IBM-compatible computers
MAC-OS Exclusively used in Apple Macintosh brand computers
UNIX Commonly used in mainframe and minicomputers
The application programs are tools that help you accomplish your work, such as designing, drafting, rendering, word-processing and project management. There are hundreds of application programs available for almost every profession.   Notes:
  • CADD programs are available for almost every category of computer. A basic understanding of the operating system is important while working on a computer.
      • The application program must be compatible with the operating system.
      • If you are to select a CADD system, the first step is to select an application program (software) that meets your requirements. After the program is selected, the next step is to select the hardware that can run the program. Keep in mind that there are complete systems available that include both compatible hardware and software.
    CADD Hardware
    The following are the main hardware components of CADD:
  • System unit
  • Central processing unit
  • Memory
  • Hard disk, floppy disk, CD-ROM
  • External storage devices
  • Monitor
  • Printers and plotters
  • Keyboard
  • Digitizer, puck and mouse
  • Note: The above topics are described in detail in CADD PRINTER.
    CADD Software
    A CADD program contains hundreds of functions that enable you to accomplish specific drawing tasks. A task may involve drawing an object, editing an existing drawing, displaying a view of the drawing, printing or saving it, or controlling any other operation of the computer. The functions contain a number of commands that enable you to specify exactly what you want to do and how you want to do it.

    The functions are organized into modules that provide easy access to all the commands. The CADD program is divided into modules such as draw, edit, data output, function control, data storage and management. A program may also have a number of specialized functions such as layers, database and 3D. Let's have a look at the CADD modules:

    • Draw
    • Edit
    • Data output
    • System control
    • Data storage and management
    • Special features
    The draw module provides access to all the drawing functions of CADD. Whenever you need to draw something this group of functions is used. The draw module enables you to draw lines, arcs, circles, ellipses, text, dimensions, symbols, borders and many other drawing components.

    Draw is CADD's most frequently used module because all drawing work is accomplished using it.

    The edit module lets you change existing drawing elements and manipulate them in a number of ways. You can move, copy or erase drawing components. You can enlarge or reduce the sizes of diagrams or change the color and line type of drawing components. You can also change the size and style of text and dimensions, as well as edit a dimension to show different units of measurement. A good CADD program is designed to change the appearance of all drawing elements created with CADD.

    The edit functions also act as convenient drawing-aid tools. They enable you to join missing corners of lines, trim drawing components along a line, stretch them to fit a new shape, etc. The list of editing capabilities goes on and on. The edit functions make CADD a dynamic drawing tool.

    Data Output
    The data output module enables you to display drawings on the screen and then print them on paper. There are two separate sets of functions that help accomplish this:

    * View-display functions
    * Print/plot functions

    The view-display functions allow you to display different views of a drawing on the screen. These functions are used quite often, because every time you need to draw something or edit something, you need to focus on that portion of the drawing. With the help of view-display functions, you can zoom in on a specific portion of the drawing.

    The print and plot functions allow you to print drawings using a printer or a plotter. You can control many aspects of printing and plotting. You can print the same drawing in different sizes by applying the appropriate scale factor. You can plot the drawings with specific colors, pen thickness, and line types.

    Data Storage and Management
    The data storage and management module allows you to store and manage drawing data. Through the use of the functions in this module, you can store drawings as files on the hard disk. You can manage the files in directories and sub-directories, and move, copy or delete them as needed.

    CADD data management functions also let you translate drawings created by other CADD programs. These functions convert drawing data to a generic format that can be read by any CADD program. Data exchange format (DXF) is one of the common data translation formats used by CADD programs. There are a number of data exchange formats available.

    System Control
    The system control module (also known as system defaults) allows you to control how CADD works. CADD programs are designed for a broad range of professionals, including architects, designers, engineers and surveyors. With the help of system control functions, you can set the working environment of CADD to suit your needs.

    Example: You can set the type of units that you will be using, the accuracy of the units, a style for dimensions and text, colors, layers, line type in a drawing, etc. Additionally, you can customize screen menus, the display of colors on the screen, resolution of the screen, size, the speed of the cursor, etc.

    You can also specify whether the selected defaults should apply to a single drawing, to a specific project, or to all the projects in a specific category. The defaults can be set on a temporary or permanent basis.

    Special Features
    CADD programs usually offer a number of special features that make working with CADD easier and allow you to automate many drawing tasks. For example, you can create layers in a drawing that allow you to segregate drawing components. You can develop spreadsheets and databases that can be used to create many types of project reports. You can create three-dimensional (3D) drawings, such as isometrics and perspectives, with the help of 3D functions. You can also accomplish many other automated tasks with the help of macros.

    The number of special features a CADD program has or how elaborate they are varies from one program to another. Some vendors sell specialized features as separate packages, while others include them in a single package. It all depends how a program is written, how big or small it is, and how it is sold.

    Important Tip:

    The functions of CADD are like the tools of a handyman. All of the tools are essential for working. Some are used more frequently than others are, but each has its own importance.

    CADD User Interface
    CADD user interface provides the environment and the tools that allow you and the computer to communicate. Each CADD program establishes an environment that best suits its purpose. The goal is to make working with CADD efficient. Most programs use a Graphic User Interface (GUI) to communicate with the user. The GUI provides visual aids for quick data entry. You are given tools to select functions, enter textual or mathematical data, locate points in the drawing window, select objects in the drawing window, etc.

    The following are the most common ways to communicate with CADD:

    • Using the CADD menus
    • Entering commands in the command window
    • Using the tool buttons
    • Using the dialog boxes
    • Working in the drawing area
    Note: The above topics are described in detail in CADD PRIMER.

    Note: CADD PRIMER is illustrated with more than 100 diagrams. The above diagram is an example from CADD PRIMER showing CAD tool buttons.

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