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Digitized by the Internet Archive 
 in 2013 
 
 http://archive.org/details/dragonusersmanua934watt 
 
UIUCDCS-R-78-934 
 
 ~7?itMt 
 
 Cjf^ 
 
 UILU-ENG 78 1726 
 COO-2383-0050 
 
 THE DRAGON USERS' MANUAL 
 
 by 
 
 Peter Watterberg 
 Virginia Lo 
 
 August 1978 
 
 DEPARTMENT OF COMPUTER SCIENCE 
 UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN 
 
 URBANA, ILLINOIS 
 
UIUCDCS-R-78-934 
 
 THE DRAGON USERS' MANUAL 
 
 by 
 
 Peter Watterberg 
 Virginia Lo 
 
 August 1978 
 
 DEPARTMENT OF COMPUTER SCIENCE 
 
 UNIVERSITY OF ILLINOIS AT URBANA- CHAMPAIGN 
 
 URBANA, ILLINOIS 61801 
 
 Supported in part by the Department of Energy under grant ENERGY/EY-76-S-02-2383. 
 
TABLE OF CONTENTS 
 
 1. Introduction 1 
 
 2. Overview of DRAGON 4 
 
 2.1 Network Basics 4 
 
 2.2 The Macro 7 
 
 2.3 DRAGON Libraries 9 
 
 3. Getting Started 11 
 
 4. Network Construction Phase 12 
 
 4.1 Typed-in Commands 13 
 
 4.2 Joystick Functions 15 
 
 Restricting Parameters 15 
 
 Mnemonic Center Star 17 
 
 The Joystick Buttons 17 
 
 Function List 18 
 
 4.3 The Menu and Mnemonic Selection 28 
 
 5. Mnemonic Construction Phase 31 
 
 5.1 Typed-in Commands 31 
 
 5.2 Joystick Functions 32 
 
 Function List 32 
 
 Bibliography 35 
 
THE DRAGON USERS' MANUAL 
 1. INTRODUCTION 
 
 DRAGON is part of a system of programs developed at the 
 University of Illinois for the purpose of modelling the 
 behavior of continuous network systems based on ordinary 
 differential equations (see figure 1) . Input to the modelling 
 package was originally only in the form of text statements 
 (card images) describing the components and attributes of the 
 network. DRAGON was created to allow the user to define a 
 network graphically in much the same manner as one might sketch 
 the network using pencil and paper. 
 
 The advantages of DRAGON'S graphical representation of a 
 network over the original text-oriented representation are 
 enormous. Networks are usually described and manipulated as 
 two-dimensional diagrams and are much more comprehensible in 
 this format. In addition, DRAGON allows the user to create and 
 use the standard symbols traditionally associated with a 
 particular class of networks. For example, under DRAGON, 
 electrical networks can be defined using the conventional 
 engineering symbols for resistors, capacitors, batteries, etc. 
 
 These goals are accomplished through the use of DRAGON'S 
 network definition functions, drawing functions, and the 
 network macro menu. The network definition functions enable 
 the user to specify the components of the network being created 
 and to characterize the network by a set of equations and 
 
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parameters. After the network has been defined, the user may 
 then design a simple graphic mnemonic to represent it and add 
 the network to the network macro menu. Addition of a network 
 to the macro menu causes the network to become available for 
 inclusion in a hierarchical fashion as a sub-network within 
 larger more complex networks. When a macro is included in a 
 network its mnemonic representation is displayed on the 
 graphics screen. Thus drawing a network using DRAGON consists 
 primarily of the selection and positioning on the screen of 
 previously defined mnemonic symbols. The network diagram is 
 enhanced using the DRAGON drawing functions to add lines and 
 textual information. Networks defined under DRAGON are saved 
 in the DRAGON network library and can then be accessed at any 
 time for input to the model analysis and simulation programs. 
 
 DRAGON replaces GRASS, an earlier attempt at a graphical 
 input program for the modelling system. GRASS was implemented 
 in machine language and had become complex and inflexible. 
 DRAGON was written in GIML [1], an interpreted graphics 
 language specially designed to facilitate the development of 
 interactive graphics programs. DRAGON is currently being run 
 on a PDP-11/35 using Computek 400 terminals. A joystick is 
 used to position the cursor on the graphics screen and this 
 information is communicated to the DRAGON program using the 
 joystick hit buttons. DRAGON can be run on any PDP-11 with a 
 UNIX operating system and graphic terminals with cursor 
 position input devices. 
 
2. OVERVIEW OF DRAGON 
 
 2.1 Network Basics 
 
 This section of the users 1 manual presents a brief 
 introductory description of the basic building blocks used to 
 construct a network and the way DRAGON handles these items 
 graphically. A detailed account of these items, their roles in 
 a network, and their relationships to each other can be found 
 in Runge [2] . 
 
 In general, a network consists of terminals , (also called 
 nodes) , and a set of equations describing the relationship 
 between these terminals. The user assigns to each terminal a 
 terminal type which has been predefined by the user as having a 
 set of associated variables. For example, a terminal that is 
 assigned to be of type "electric" may then have the variables 
 "current" and "voltage" associated with it. Under DRAGON, the 
 position of a terminal is specified with the use of the 
 joystick and the "term" function, and each terminal is 
 displayed on the screen as "0". A unique number is 
 automatically assigned to each terminal as it is created so 
 that it can be referenced unambiguously in the equations. At 
 the user's request, this number is displayed as a subscript 
 near the terminal "0" symbol. Each terminal is also designated 
 by the user as either internal or external. The distinction 
 between these two types of terminals will be explained below. 
 
It is often desirable to relate two terminals so that they 
 function as if they were actually one terminal in the model. 
 For example, connecting two terminals in an electric network 
 short circuits them. A "connect" function is available for 
 this purpose. When two terminals are connected, they are 
 joined by a line to represent the connection visually. 
 
 Equations are used to describe attributes of a terminal or 
 relationships between terminals. For example, a terminal that 
 is to act as a ground in an electrical network has an equation 
 setting its voltage potential to zero. The fact that two 
 terminals are connected by a resistor can be indicated by 
 relating the two terminals with resistor equations. (However, 
 once a resistor macro element has been defined, the same fact 
 can be specified by inserting an instance of a resistor between 
 the two terminals.) 
 
 All of the equations in a network are entered by the user 
 as text information and are displayed on the screen in a group 
 under the heading "equations." The user has the options to add 
 or delete equations at any time, to suppress display of the 
 equations, to request that equations be displayed if they have 
 previously been suppressed, and to move the list of equations 
 as a group to any position in the draw area. 
 
 Functions , local variables , and global variables are used 
 in equations. Each of these items is entered by the user as 
 text and displayed as a group under its own heading. Each text 
 
group can be manipulated in the same way as the equations text 
 group, i.e., modified, displayed on request, and moved in the 
 draw area. A set of standard functions, such as sine, cosine, 
 and square root, are predefined for all networks and need not 
 be declared in the function text group. See [2] for a complete 
 list of these predefined functions. 
 
 If the user plans to store a network in the macro menu for 
 inclusion in large networks, it is useful to assign a set of 
 parameters to the network. These parameters can be given 
 default values when the network is defined. Later, each 
 particular instance of the macro which is selected for 
 inclusion can have particular values assigned to its 
 parameters. Parameters and their default values are handled by 
 DRAGON in the same manner as equations, locals, globals, and 
 functions. In addition, there are two DRAGON functions for the 
 assignment and modification of parameter values. 
 
 Initial values can be assigned to any of the network's 
 variables, parameters, or to derivatives of the variables and 
 parameters. Again, these initial values are entered as text 
 and can be manipulated in the same way as previously described 
 textual information. 
 
 There are two additional features available under DRAGON 
 which are not essential to the definition of the network but 
 which greatly increase the effectiveness of the graphical 
 
representation of the network. First, the user has the ability 
 to draw lines on the screen. These lines can be used to draw 
 symbolic pictures to represent the equations relating 
 terminals, to add clarity by logically separating sections of 
 the network, or for whatever purpose the user desires. Second, 
 the user can add comment text wherever desired. The comment 
 text can be dispersed into arbitrarily many groups. Each group 
 can be deleted or moved around on the screen independently of 
 the other groups. The comment text groups are not displayed 
 with a header. 
 
 2.2 The Macro 
 
 If the user were required to explicitly define every 
 component of a network, the usefulness of DRAGON would be 
 severely limited. However, DRAGON'S macros allow the use of 
 simple graphic symbols to represent entire networks. The use 
 of macros makes possible arbitrarily large networks (limited by 
 computer word size and storage) to be displayed on a 
 restr ictively small screen. 
 
 A macro in the DRAGON system consists of a picture ( the 
 mnemonic ) , a name, and a parameter list. Strictly speaking, 
 the mnemonic is just the pictorial representation of the macro; 
 however, the two terms "macro" and "mnemonic" are often used 
 interchangeably in this manual. A given macro can be included 
 as an element in other larger networks. Inclusion of the macro 
 is equivalent to inclusion of the entire network the macro 
 
represents. Thus the DRAGON macro is analogous to the 
 subroutine or macro in a conventional programming language. 
 The network that the macro represents will have several 
 specially designated terminals, called external terminals , by 
 which the macro can be connected to the including network. 
 
 As a simple example, consider a resistor. A network that 
 describes a resistor can be constructed using two terminals and 
 by listing the equations that describe the voltage and current 
 relationships. A macro can be made for the resistor consisting 
 of a picture (probably the traditional zig-zag line) , a name 
 ("resistor"), and a parameter R with some default value, say 10 
 ohms. The macro is saved and can then be used in the 
 construction of other electric networks by connecting the 
 resistor picture between any two terminals in the including 
 network. If a resistance is desired that is different from the 
 default 10 ohms, the default value can be changed. The process 
 of using the resistor macro is much faster than entering all 
 the equations associated with a resistor. Furthermore, the 
 pictorial representation is more easily comprehended than a set 
 of equations. A resistor is a very simple example of the use 
 of macros. The advantages of macros become even more 
 pronounced as the complexity and size of the networks increase. 
 
 Macros can be nested within macros to any depth. For 
 example, several resistors could be used in the construction of 
 a transistor model network. The transistor could be 
 represented by a mnemonic which could then be used in an 
 amplifying network and so on. This feature of DRAGON gives 
 
organization and logical clarity to large networks and removes 
 the restriction of limited screen size. 
 
 The basic components of a network — the terminals, 
 equations, functions, locals, globals, parameters, and initial 
 values -- are all defined during the network construction phase 
 of DRAGON. When the user decides to create a macro for a 
 network the macro construction phase of DRAGON is entered. 
 
 The terminals of the macro are those terminals of the 
 network that were designated as external terminals in the 
 network construction phase. The macro is connected into larger 
 networks through these external terminals. The entire set of 
 parameters that were defined for the network in the network 
 construction phase are also displayed with the macro in the 
 macro construction phase. They are always visible and can be 
 moved but any changes to these parameters must be done in the 
 network construction phase. The mnemonic is created by drawing 
 the desired symbol using the joystick and DRAGON'S graphic 
 functions. Finally, comment text can be added as part of the 
 mnemonic. It is handled exactly like the comment text in the 
 network except that it cannot be made invisible. 
 
 2.3 DRAGON Libraries 
 
 The DRAGON program maintains two network libraries for the 
 user. The DRAGON library LIB contains the DRAGON work files 
 and a file for each network created and saved by the user. The 
 file for each network is used during construction and 
 
10 
 
 manipulation of the network under DRAGON. Each network 
 processed by the DRAGON model command (see section 4.1) is also 
 saved in the DRAGON library MODEL. The MODEL library file for 
 a network is the representation of the network in the form of 
 MODEL text statements and is essentially ready for input to the 
 
 4 
 
 MODEL analysis program. In the MODEL library file, the network 
 information for all macros contained within the main network 
 has been added while purely graphic information has been 
 deleted. A file in the MODEL library is still in the form of a 
 GIML file and therefore must be processed one step further 
 before input to the model analysis and simulation programs. 
 
 The version of DRAGON running on the PDP 11/35 makes use 
 of the UNIX file system for maintenance of its two libraries. 
 LIB and MODEL exist as directories in the UNIX file system and 
 the network file within each library is created as a UNIX file 
 within the appropriate directory. Thus if the user saves a 
 DRAGON network under the name "resistor" it will be saved in 
 the UNIX file . /LIB/resistor . 
 
11 
 
 3. GETTING STARTED 
 
 DRAGON currently runs on a PDP-11/35 connected to a 
 Computek 400 terminal. The terminal accepts two kinds of 
 input: text typed in on the keyboard and joystick "hits." The 
 joystick is a lever that controls the position of a cursor on 
 the display screen. Pressing one of the twelve buttons on the 
 joystick box sends the position of the cursor to the DRAGON 
 program. The process of moving the cursor to a desired 
 position on the screen and pressing a button is called "making 
 a hit" or " joysticking . " 
 
 To run DRAGON, login to UNIX and then execute the DRAGON 
 program under the GIML interpreter. The greeting "DRAGON is 
 breathing, fire away" will appear on the screen along with a 
 list of all networks that were created and saved in previous 
 runs of DRAGON. To start from scratch, make a hit in the box 
 that says "start from scratch." To continue working on a 
 network or to edit a network, make a joystick hit on the name 
 of the desired network. 
 
12 
 
 4. NETWORK CONSTRUCTION PHASE 
 
 DRAGON is now in the network construction phase. Most of 
 the work is done in this phase. The screen is divided into 
 four sections (see figure 2) . The major portion of the screen 
 is the draw area where the network is built up and displayed. 
 If an old network was chosen for work, the draw area will 
 contain its current version. Otherwise, the draw area will be 
 blank. The function selection area contains up to 21 functions 
 which are used in the construction and editing of networks. 
 The menu area contains up to 16 names of macros which the user 
 may select and add to the current network. In the lower 
 lefthand corner of the screen are the words "redraw" and 
 "mnemonic." Joysticking "redraw" redraws the screen, removing 
 spurious marks and old information. Hitting "redraw" also 
 clears any function that was waiting for input so "redraw" is a 
 good thing to do if the user forgets what's happening. Hitting 
 "mnemonic" causes DRAGON to change to the macro construction 
 phase for creating and saving macros. 
 
 In the network construction phase, DRAGON responds to 
 joystick hits in the four areas just described and to special 
 typed-in commands. It is often necessary to joystick a 
 terminal, line endpoint, or mnemonic in the draw area. It may 
 be difficult to position the cursor at the exact location of 
 the object, so it is sufficient to be within a one letter 
 radius about the desired object. A hit on a text line is 
 
13 
 
 achieved by joysticking any character in the line. Whenever, a 
 joystick hit is made that causes DRAGON to take some action, it 
 will be echoed in some fashion. A hit on a text line of any 
 kind is acknowledged by flashing the line. A hit on a terminal 
 line endpoint or mnemonic star is echoed by a dash mark at the 
 hit site. When selecting functions or macros, the one closest 
 to the hit is selected and flashed back. If the wrong item 
 flashes back, simply try again. 
 
 4.1 Typed-in Commands 
 
 save -- To put the current version of the network into the 
 
 network library LIB, the user must type "save" followed 
 by the network name. A network name must start with a 
 letter and be no more than nine characters long. Any 
 portion of a mnemonic associated with the network is 
 saved as well but the network is not put into the menu 
 of available macros when saved in network construction 
 phase. DRAGON will respond with "network saved as 
 xxxx" or "xxxx is already in the library." If the user 
 wishes to save an updated version of an old network 
 under the original name, he must first delete the old 
 version and then type in the save command. 
 
 delete -- This commands removes networks from the library. 
 
 "Delete" must be followed by one or more blanks and the 
 name of the network to be deleted. DRAGON will respond 
 with "xxxx is deleted" or "non-existent network." 
 
14 
 
 model -- If the user wishes to prepare a network for input to 
 the MODEL analysis program [2] , he should type the 
 command "model." DRAGON will ask for the network name 
 and then create MODEL definition statements from the 
 DRAGON network. When the information from all levels 
 of macros has been obtained, DRAGON will allow the user 
 to type in additional MODEL general definition 
 statements (i.e., RENAME, UNIT, TITLE, FUNCTION, 
 SUBROUTINE, TYPE, FLIST, MAP, and ABORT statements). 
 The user should hit return to indicate completion of 
 these MODEL statements. The entire set of MODEL 
 statements are then saved in the MODEL library under 
 the same name as the equivalent DRAGON network. The 
 MODEL file for the network must then be processed by an 
 independent program to convert it from the GIML file 
 structure to card images for input to the MODEL 
 program. After the MODEL file is complete, DRAGON 
 returns to the initial signon message so the network 
 that was current before the model command was issued is 
 NOT retained. 
 
 restart -- Typing "restart" will bring the user back to the 
 
 original DRAGON signon message. The working network is 
 not saved. The user can now continue as though DRAGON 
 had just been started up. 
 
 quit -- To exit from DRAGON and return to UNIX, the user can 
 type "quit." The working network is not saved. 
 
15 
 
 Any other typed message is ignored. 
 
 4.2 Joystick Functions 
 
 There is room for 21 functions in the function selection 
 area at one time, but there are more than 21 functions 
 available. To see the entire list and to select functions 
 other than the current 21, joystick the letters "fnsl" in the 
 far righthand part of the function selection area. The 
 complete function list will appear in the draw area. To select 
 a function from the master list for placement in the available 
 list, joystick that function and then joystick the slot in the 
 function selection area where it is to be placed. Joysticking 
 a function in the function selection area without first 
 selecting a replacement from the master list will remove the 
 function from the available list but not replace it with 
 anything. When the function selection area is arranged as 
 desired, joystick "return" in the lower lefthand corner. 
 
 Restricting Parameters 
 
 When a function is selected from the function selection 
 area, it operates in the most general way. However, some 
 functions will accept restricting parameters which serve to 
 narrow the function's field of action. The restricting 
 parameters are the basic building blocks of a network 
 (terminals lines, text, equations, parameters, functions, local 
 
16 
 
 variables, global variables, initial values, and output 
 variables) and thus each restricting parameter is itself a 
 function in the function selection area. Therefore each of 
 these basic functions serves a double purpose: it may be 
 joysticked in order to activate that particular function, or it 
 may be joysticked as a restricting parameter in conjunction 
 with one of the functions that accepts restricting parameters. 
 
 For example, the move function allows the user to specify 
 what item in the draw area is to be moved. If no restricting 
 parameter is chosen for move, anything and everything that is 
 picked out by the joystick hit will be moved. In this case, 
 many different items can be moved in sequence. However, if a 
 restricting parameter is joysticked immediately following the 
 selection of the move function, only that parameter will be 
 affected. Thus if "move" is joysticked and then "term" is 
 joysticked, only terminals can be moved. 
 
 When selecting a restricting parameter for a function, the 
 parameter must be joysticked immediately after the function is 
 hit; there can be no intervening actions. A function that 
 accepts a restricting parameter will accept only one such 
 parameter. When a joystick button remembers the function it 
 selects, it also remembers the restricting parameter if one was 
 chosen (see joystick button section below). The restricting 
 parameters allowed for various functions are specified in the 
 function list below. 
 
17 
 
 Mnemonic Center Star 
 
 All mnemonics that have been included and displayed in the 
 draw area are accompanied by a center star ("*") located near 
 the center of the mnemonic. This star is used to specify which 
 mnemonic has been chosen for various functions such as move, 
 delete, and chparms. 
 
 The Joystick Buttons 
 
 There are 12 buttons on the joystick box. To increase 
 speed and ease of operation, these buttons are programmed to 
 remember the functions when they are pushed. If a button is 
 used to select a function, the button becomes tied to that 
 function until it is used to select another function. For 
 example, if button 7 is used to joystick the move command, it 
 can then be used repeatedly to move things around in the draw 
 area. Other intervening functions can then be executed, but as 
 long as they are done with buttons other than 7, number 7 can 
 still be used to move things without reselecting the move 
 command. Using a button to hit fnsl, redraw, or mnemonic does 
 not cause the button to forget what function it had previously 
 been tied to. The button memory operates as described above 
 for macros selected from the menu area as well as for functions 
 selected from the function selection area. 
 
18 
 
 Function List 
 
 term -- Once a joystick button has been used to hit this 
 
 function, that button can be used to add terminals to 
 the network by simply joysticking the spot in the draw 
 area where the terminal is to be placed. The terminal 
 will appear as an "0" in the draw area. The position 
 of terminals may be affected by the "h or v" command 
 (see below) . 
 
 line --This function allows the user to add lines to the 
 
 picture. These lines have no effect on the network 
 model; they are purely for clarity and aesthetics. 
 Normally it takes two hits in the draw area to indicate 
 the two endpoints of the desired line. This 
 requirement can be affected by the "continue" and "h or 
 v" commands (see below) . 
 
 continue -- This function acts as a switch. The switch is 
 
 initially off. Thereafter, it changes modes whenever 
 the continue function is joysticked, i.e., if it was 
 off, it turns on and vice versa. When continue is off, 
 the user must joystick both endpoints of the line to be 
 drawn. Thus, normally two hits per line are needed. 
 When continue is on, the last endpoint of the previous 
 line is taken to be the first endpoint of the next 
 line. In this case, only one hit per line is 
 necessary. If the switch is on and no line has yet 
 
19 
 
 been drawn, the default first endpoint is the center of 
 the draw area. The continue function affects both 
 lines and macros. Only the effect of the continue 
 function on lines is discussed here. Its effect on 
 macro selection is described in section 4.3. 
 
 h or v -- This function also acts as a switch in the same 
 
 manner as the continue function. It is initially off. 
 When h or v is off, lines are drawn where the user 
 indicates with the joystick hits. When it is on, only 
 horizontal and vertical lines are drawn. The first 
 endpoint is either marked by a joystick hit or, if 
 continue is on, it is assumed to be the last endpoint 
 of the preceding line. The second endpoint is marked 
 by a joystick hit but then it is moved to make an 
 exactly vertical or horizontal line. If the indicated 
 line is more nearly horizontal than vertical, the 
 second endpoint is moved up or down to make the line 
 horizontal; if the indicated line is more vertical 
 than horizontal, the second endpoint is moved in the 
 horizontal direction to make the line vertical. 
 
 text -- This function adds comment text to the network. As 
 
 with lines, comment text is for clarity and aesthetics. 
 To add text, first joystick the text function and then 
 joystick the spot in the draw area where the text is to 
 appear. The user can then type in the text. To 
 terminate the text mode, another joystick hit must be 
 
made; any kind of hit will do. Text is organized in 
 groups. Each group may have as many lines of text as 
 desired and there many be as many groups as desired. 
 Each group is moved and displayed as a unit but lines 
 may be edited individually. 
 
 equation -- To add equations, joystick the equation function 
 and then type in the equations, one per line. They 
 will appear under the heading "equations." Equations 
 are moved as a group but deleted individually. 
 
 parm -- This function works exactly like the equation function. 
 It is used to enter the parameters associated with the 
 network. Default values may be specified if desired by 
 simply equating the parameter to the desired default 
 value. 
 
 locals — This function works exactly like the equation 
 
 function. It is used to declare and assign values to 
 local variables. 
 
 globals -- This function works exactly like the equation 
 
 function. It is used to declare and assign values to 
 global variables. 
 
 funcs -- This function works exactly like the equation 
 
 function. Any non-standard function that is used in an 
 equation must be defined using the func function. The 
 user joysticks the func function and then types in the 
 FORTRAN text defining the function. 
 
21 
 
 initial -- This function works exactly like the equation 
 
 function. It is use to assign initial values to the 
 variables, parameters, and the derivatives of the 
 variables and parameters of the network. 
 
 output -- This function works exactly like the equation 
 
 function. It is used to enter the names of those 
 network variables whose histories are to be recorded in 
 the output from the numerical simulation programs. The 
 output variables should be entered one per line. 
 
 move -- To move an object in the draw area, first joystick the 
 move function, then the object to be moved. After 
 DRAGON signals that the hit was received, joystick the 
 new location for the object. When moving lines, only 
 one endpoint of any particular line is moved at a time, 
 but if the endpoints of several different lines 
 converge at one point (i.e., are within the hit radius 
 of one letter around the joystick hit) all the 
 endpoints will be moved. All other objects are moved 
 individually. For example, if there is more than one 
 terminal in the hit radius, only one is moved (the one 
 with the higher terminal number) . Move accepts all of 
 the basic building blocks as restricting parameters 
 (terminals, lines, text, equations, parameters, 
 functions, local variables, global variables, initial 
 values, output variables, and macros). 
 
22 
 
 delete -- To delete an object, it is only necessary to hit it 
 
 with the joystick, so be careful. To delete a line, it 
 is necessary to joystick the restricting parameter 
 "line" and then to joystick both endpoints of the line 
 to be deleted. As with move, delete accepts all of the 
 basic building blocks as restricting parameters. 
 
 visible -- This function is for use with text and terminal 
 
 information. When the user joysticks any of the text 
 functions (text, parm, equations, locals, globals, 
 functions, initial, output), the heading and text 
 become visible on the screen. To make them invisible 
 (e.g. to avoid clutter) joystick the visible function 
 and then the text group to be made invisible. The 
 information about a terminal (its number and type) is 
 initially invisible. To make this data visible, it is 
 necessary to joystick the terminal with the visible 
 joystick button. The information can be made invisible 
 again by joysticking the terminal again. 
 
 connect -- Terminals may be connected making them essentially 
 one terminal. Joystick the first of a pair and then 
 the second with the connect joystick button. A 
 connection between terminals shows up as a line but 
 this line cannot be treated in the same way as a line 
 created with the line function. Connect is also used 
 to disconnect terminals. If a pair of terminals is 
 connected and they are hit with the connect joystick 
 
23 
 
 button, they will become disconnected. 
 
 make x -- This function also works as a switch. Hitting a 
 
 newly-created terminal with this function makes it an 
 external terminal. If the terminal is already external 
 and it is hit with this function, it becomes an 
 internal terminal. 
 
 show -- This function is used if a user is not familiar with a 
 mnemonic name in the macro menu or if he wants more 
 information about a mnemonic before including it in the 
 working network. First joystick "show"; a list of 
 show functions will appear across the bottom of the 
 screen. Next joystick the name of a macro in the menu 
 area. The mnemonic will then be displayed in the draw 
 area (the working network is safe) . To see the network 
 represented by this mnemonic joystick the show function 
 "network." To see the parameters, locals, globals, 
 equations, functions, initial values, and output 
 variables for this network, joystick the show function 
 "text." To see the parameters and pseudo-id numbers of 
 any macros contained within this network, joystick the 
 corresponding macro center star in the draw area. To 
 view the mnemonic again joystick "mnemonic." To change 
 the mnemonics in the menu, joystick "next"/"last" to 
 see the following/previous 16 mnemonic names. Joystick 
 "return" in the lower lefthand corner to get back to 
 network construction mode. 
 
24 
 
 asntypes -- This function is used to assign types to terminals. 
 While in asntypes mode, individual joystick buttons are 
 not distinguished and the functions associated with 
 each button in the general construction mode are 
 unaffected by the use of the buttons in asntypes mode. 
 After the asntypes function is hit, the menu area will 
 contain a list of the terminal types available and the 
 function area will contain the asntypes functions. A 
 maximum of eight types are displayed in the menu at any 
 one time. To see the next/previous eight types 
 joystick "next"/"last . " To assign terminal types, 
 select a type from the type menu with the joystick and 
 then hit the desired terminal (s) . The type will be 
 displayed near the terminal (s) to which it has been 
 assigned. When a type is selected it is remembered 
 until another type or another asntypes function is 
 chosen. Thus to assign a type to several terminals it 
 is necessary to hit the type in the menu only once and 
 then the desired terminals in succession. To delete a 
 terminal type assignment, hit "delete" and the terminal 
 whose type is to be removed. To assign one terminal 
 type to all terminals in the network, hit the desired 
 terminal type and then hit "all." If the screen should 
 become cluttered at any time, joystick "redraw" and all 
 type names in the draw area will be erased. To view 
 the current type assignments hit "visible" and all 
 terminal types and numbers will be displayed. When all 
 
25 
 
 type assignments are completed, joystick "return" to 
 get back to network construction mode. 
 
 modtypes -- Joystick this function to add or delete terminal 
 
 type definitions to the type list. The screen will be 
 erased and the type definitions and the modtypes 
 functions will be displayed on the screen. At most 
 eight types are displayed at any one time. To see the 
 next/previous eight type definitions joystick 
 "next"/"last. " To delete a type definition hit 
 "delete" and the type to be deleted. To add a new type 
 definition to the list hit "add" and then enter the 
 type definition. Each type definition consists of two 
 lines of text. Line 1 is the type name and must be 
 nine or fewer characters. Line 2 is the definition and 
 can be up to 80 characters in length. See Runge [2] 
 for a discussion of the terminal type definition. 
 After the second line is entered, the new definition 
 will be inserted in its proper alphabetic location in 
 the list. For convenience, deletions and additions can 
 also be made by directly joysticking the type 
 definition or by directly entering text without 
 previously hitting the corresponding modtypes function. 
 The check function can be used to double check all 
 deletions. It acts as an on/off switch. If check is 
 on, any deletions will cause the question "are you 
 sure?" to be displayed on the right side of the screen. 
 If the answer "yes" is entered, the type is deleted; 
 
26 
 
 otherwise, the deletion is ignored. To get back to 
 network construction mode, hit "return." 
 
 renumber -- After adding and deleting many terminals, the 
 numbers assigned to the terminals may not be 
 consecutive. This function renumbers the terminals 
 consecutively in the order in which they were created. 
 The externals block, the connect block, and block d for 
 each macro are updated to correspond to the new 
 numbering. However, renumber does NOT alter the 
 terminal numbers where they appear in equations and 
 other text groups. It is the user's responsibility to 
 edit the equations, etc. to correspond to the new 
 terminal numbers. 
 
 asnparms -- This function allows the user to assign parameter 
 
 values to each of the macros that have been included in 
 the working network. Joysticking "asnparms" causes the 
 asnparms functions to be displayed across the bottom of 
 the screen. The macros are then automatically 
 presented one by one to the user. For each macro, the 
 current parameter assignments are displayed and a "-" 
 appears before each parameter in the list. To change 
 the parameter value, type in the entire new line (both 
 variable name and value). To leave the parameter 
 unchanged, simply hit return and continue on with the 
 next line. When all lines have been dealt with, the 
 process will continue automatically with the next 
 
27 
 
 macro. At any time the user can hit "next" or "last" 
 to cease processing of the current macro and switch to 
 the next or previous macro. Hitting "same" allows the 
 user to re-enter parameters for the current macro. If 
 the screen should become too cluttered, joystick 
 "redraw." When all parameter assignments have been 
 made, joystick "return" to get back to network 
 construction mode. 
 
 chparms -- This function is used if just one or a few macro 
 
 parameter assignments must be altered. (The asnparms 
 function should be used if many or all macro parameters 
 are to be assigned.) Joystick "chparms" and then the 
 macro center star of the desired macro. The parameters 
 will be displayed near the macro. DRAGON will display 
 an arrow beside each line of parameter text. The user 
 can either type in the entire new line or press the 
 return key to retain the old line. 
 
 pseudo -- The pseudo function enables the user to assign a 
 
 unique terminal id number (a negative number) to the 
 terminals of any or all macros contained within the 
 working network. See Runge [2] for a discussion of the 
 conditions requiring use of pseudo id numbers. To 
 assign pseudo id numbers to a macro at the time it is 
 added to the working network, joystick "pseudo" and 
 then proceed as usual to select a mnemonic from the 
 menu and connect it into the network. To assign pseudo 
 
28 
 
 id numbers after a macro has been included in a 
 network, joystick "pseudo" and then the macro center 
 star. In both cases, the new pseudo id numbers will 
 appear on the screen near the associated terminals (the 
 terminals of macros within a network appear only as the 
 endpoints of connecting lines) . The pseudo numbers of 
 a macro can be seen at any time by joysticking 
 "visible" and the center star of the macro. 
 
 4.3 The Menu and Mnemonic Selection 
 
 The menu is a circular list in alphabetic order of the 
 macros available for inclusion in the current network. Sixteen 
 macro names are visible at an given moment. At the bottom of 
 the menu area are the words "last" and "next." To advance from 
 the current sixteen macros to the next group, joystick "next." 
 To get from the current sixteen macros to the previous group, 
 joystick "last." Joysticking "next" when one is at the end of 
 the list causes the first sixteen macros to appear on the 
 screen; joysticking "last" when the first sixteen macros are 
 visible will display the end of the list. 
 
 To select a mnemonic from the list, simply joystick the 
 one desired. The name should flash back. If the wrong name 
 flashes, just try again. The joystick buttons remember 
 mnemonics in the same way that they remember functions. Once a 
 button has been used to select a mnemonic, that button can be 
 used to put up the same mnemonic repeatedly without reselecting it, 
 
29 
 
 To put up a mnemonic up after it has been selected from 
 the menu area, it is necessary to joystick all the terminals to 
 which it is to be connected (one terminal for each of the 
 macro's external terminals). The terminals may or may not 
 already exist in the draw area. If an existing terminal is 
 joysticked, the macro is connected to that terminal. If a 
 position is joysticked where there is no terminal, one is 
 created and displayed there. When the requisite number of 
 terminals have been joysticked, the mnemonic is drawn on the 
 screen. The mnemonic is automatically rotated or reflected 
 into a position that minimizes the sum of the distances between 
 the external terminals of the macro and the terminals to which 
 it is being connected. Thus a resistor connected to two 
 horizontal terminals is displayed horizontally, and a resistor 
 connected to two vertical terminals is displayed vertically. 
 The mnemonic center star "*" is displayed near the mnemonic. 
 This star is used to specify which mnemonic is to be used in 
 various functions such as move, delete, and chparms. The 
 external terminals of the macro are not displayed but appear 
 only as the endpoints of the connecting lines. 
 
 In order to joystick all the terminals to which a mnemonic 
 is to be connected, it is necessary to know how many external 
 terminals that mnemonic has. If the user does not know this 
 number, the show function can be used to find out. 
 
 All the external terminals of a mnemonic must always be 
 
30 
 
 connected to network terminals. This means that if the user 
 deletes a terminal which is connected to a mnemonic, a new 
 terminal will be automatically created and connected to the 
 mnemonic. The new terminal is placed where the external 
 terminal of the mnemonic would appear. 
 
 If the continue switch is on and several macros are put up 
 in succession, the last terminal used for a given macro will be 
 used as the first terminal for the next macro. This feature 
 allows the user to put up a series of connected macros with a 
 minimal number of joystick hits. 
 
31 
 
 5. MNEMONIC CONSTRUCTION PHASE 
 
 When the user decides to create a mnemonic for a network, 
 the mnemonic construction phase of DRAGON is entered by 
 joysticking "mnemonic" in the lower lefthand corner of the 
 screen. In this phase, the screen consists of the draw area, 
 the function selection area, and "redraw" and "return" in the 
 lower lefthand corner. When "return" is joysticked, the system 
 switches back to network construction mode. Switching back and 
 forth between modes has no effect on the network or the 
 mnemonic and thus can be done as often as desired. 
 
 When mnemonic construction mode is entered, the draw area 
 contains the external terminals and the parameters of the 
 working network. These cannot be deleted in mnemonic mode nor 
 can additional terminals and parameters be added. The user 
 must return to network construction mode to make these changes. 
 In addition, there is a center star in the middle of the draw 
 area about which the mnemonic can be rotated. The center star 
 will be displayed when the mnemonic is selected for inclusion 
 in other networks. 
 
 5.1 Typed-in Commands 
 
 Mnemonic mode accepts the same typed-in commands as 
 network construction mode. These commands have the same 
 effects with the exception of the save command. When the save 
 command is typed in mnemonic mode, the network is saved as 
 
32 
 
 usual and the mnemonic is added to the list of available 
 mnemonics and subsequently appears in the menu area in network 
 construction mode. 
 
 5.2 Joystick Functions 
 
 Function selection operates in the same manner as in 
 network construction mode. There are twelve functions 
 available in mnemonic construction mode. All the functions are 
 visible on the screen so there is no fnsl command in mnemonic 
 mode. The buttons will remember the functions they select as 
 in network mode. Furthermore, nothing that is done in mnemonic 
 mode affects the buttons' memory in network mode. The 
 functions "move" and "delete" will accept restricting 
 parameters but "term" and "parm" cannot be used as parameters 
 for delete. 
 
 Function list 
 
 term -- Since terminals cannot be added or deleted, this 
 
 function is only useful as a restricting parameter for 
 the move command. 
 
 line -- This function works exactly like the line function in 
 network construction mode. 
 
 h or v -- This function works exactly like the h or v function 
 in network construction mode. 
 
33 
 
 continue -- This function works exactly like the continue 
 function in network construction mode. 
 
 text -- This function works exactly like the text function in 
 network construction mode. 
 
 parm -- Like term, this function can only be used as a 
 restricting parameter for the move function. 
 
 move -- This function work exactly like the move function in 
 network construction mode. 
 
 delete -- This function works like the delete function in 
 
 network construction mode with the exception that it 
 does not work on terminals or parameters. 
 
 double -- This function doubles the size of the mnemonic being 
 constructed in the draw area. 
 
 halve -- This function halves the size of the mnemonic being 
 
 constructed in the draw area. When drawing a mnemonic 
 it is more convenient to be able to draw a large 
 version of the picture. The halve function can then be 
 used to shrink it down to the size which will appear on 
 the screen when the macro is selected for inclusion in 
 other networks. In addition, the picture will lose 
 some of its raggedness when reduced. 
 
 rotate -- This function rotates the entire picture 90 degrees 
 counterclockwise. 
 
34 
 
 reflect -- This function reflects the entire picture about the 
 center vertical line. 
 
35 
 
 BIBLIOGRAPHY 
 
 [1] Hennegan, Neal M. , "GIMLI and GIML, A Machine and Programming 
 Language for Low Cost Interactive Graphical Systems," 
 Department of Computer Science Report UIUCDCS-R-77-856, 
 University of Illinois at Urbana-Champaign, 1977. 
 
 [2] Runge, Thomas F., "A Universal Language for 
 Continuous Network Simulation," 
 
 Department of Computer Science Report UIUCDCS-R-77-866, 
 University of Illinois at Urbana-Champaign, 1977. 
 
Form AEC-427 
 
 (6/68) 
 
 AECM 3201 
 
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 UNIVERSITY-TYPE CONTRACTOR'S RECOMMENDATION FOR 
 
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 1. AEC REPORT NO. 
 
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 2. TITLE 
 
 THE DRAGON USERS' MANUAL 
 
 3. TYPE OF DOCUMENT (Check one): 
 
 [XI a. Scientific and technical report 
 
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 4. RECOMMENDED ANNOUNCEMENT AND DISTRIBUTION (Check one): 
 
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 5. REASON FOR RECOMMENDED RESTRICTIONS: 
 
 6. SUBMITTED BY: NAME AND POSITION (Please print or type) 
 
 C. William Gear 
 
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 Organization 
 
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 University of Illinois 
 Urbana, Illinois 61801 
 
 Signature 
 
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 Date 
 
 August 1978 
 
 *-FOR AEC USE ONLY 
 
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3IBLI0GRAPHIC DATA 
 
 Beet 
 
 1. Report No. 
 
 UIUCDCS-R-78-934 
 
 2. 
 
 3. Recipient's Accession No. 
 
 . Title and Subtitle 
 
 THE DRAGON USERS' MANUAL 
 
 5. Report Date 
 August 1978 
 
 6. 
 
 . Author(s) 
 
 Peter Watterberg and Ginnie Lo 
 
 8> Performing Organization Rept. 
 
 No - UIUCDCS-R-78-934 
 
 . Performing Organization Name and Address 
 
 Department of Computer Science 
 
 10. Project/Task/Work Unit No. 
 
 University of Illinois 
 Urbana, Illinois 61801 
 
 11. Contract /Grant No. 
 
 ENERGY/EY-76-S-02-2383 
 
 2. Sponsoring Organization Name and Address 
 
 Department of Energy 
 9800 South Cass Avenue 
 
 13. Type of Report & Period 
 Covered 
 
 Users' Manual 
 
 Argonne, Illinois 60439 
 
 14. 
 
 5. Supplementary Notes 
 
 6. Abstracts 
 
 DRAGON is an interactive graphics program which is used to define networks 
 for the purpose of modeling and simulation by the MODEL analysis and numerical 
 simulation programs (also developed at the University of Illinois). DRAGON 
 enables the user to define a network graphically in much the same manner 
 as one might sketch the network using pencil and paper. Some features of 
 the DRAGON program include representation of arbitrarily complex networks 
 with simple graphic mnemonics, maintenance of network libraries, and a useful 
 set of network drawing and network definition functions. 
 
 7. Key Words and Document Analysis. 17a. Descriptors 
 
 network analysis 
 interactive 
 graphics 
 modeling 
 
 7b. Identifiers/Open-Ended Terms 
 
 7c. COSATI Field/Group 
 
 8. Availability Statement 
 
 unlimited 
 
 19. Security Class (This 
 Report) 
 
 UNCLASSIFIED 
 
 20. Security Class (This 
 
 Page 
 UNCLASSIFIED 
 
 21. No. of Pages 
 
 35 
 
 22. Price 
 
 ORM NTIS-35 ( 10-70) 
 
 USCOMM-DC 40329-P7I