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DRLRMA.WS4 (= "Dr. Logo Reference Manual", Appendix A) ---------- (Retyped by Emmanuel ROCHE. Posted to comp.os.cpm.amethyst by Roche on 08 Apr 2005.) ROCHE> The DRLRM6.WS4 file, when printed on A4 (12") paper is 175 pages long... So, since some persons complain about long messages, I sent it, instead, to the comp.os.cpm.amethyst Newsgroup, that nobody read anymore. With this publication, the full "Dr. Logo Reference Manual" is now available. I hope that this will encourage CP/M fans to publish interesting Dr. Logo programs for CP/M-86 (Plus)... (Amstrad 8-bit and Atari 520ST fans will also be interested in this documentation.) Appendix A: Dr. Logo error messages ----------------------------------- Table A-1. Dr. Logo error messages Number Message ------ ------- 2 Number too big 6 (symbol) is a primitive 7 Can't find lable (symbol) 8 Can't (symbol) from the editor 9 (symbol) is undefined 11 I'm having trouble with the disk 12 Disk full 13 Can't divide by zero 15 File already exists 17 File not found 21 Can't find catch for (symbol) 23 Out of space 25 (symbol) is not true or false 29 Not enough inputs to (procedure) 30 Too many inputs to (procedure) 32 Too few items in (list) 34 Turtle out of bonds 35 I don't know how to (symbol) 36 (symbol) has no value 37 ) without ( 38 I don't know what to do with (symbol) 40 Disk is write protected 41 (procedure) doesn't like (symbol) as input 42 (procedure) didn't output 43 I don't know how to do that yet 44 !! Dr. Logo system bug !! (Should not occur. Please write to Digital Research if it does.) 45 The word is too long 46 I don't have enough buffer space 47 If wants [ ]'s around instruction list 48 (varies according to disk error) 49 (symbol) isn't a parameter 50 I can't (symbol) while loading 51 The file is write protected 52 I can't find the disk drive EOF DRLRMB.WS4 (= "Dr. Logo Reference Manual", Appendix B) ---------- (Retyped by Emmanuel ROCHE.) Appendix B: Dr. Logo control and escape character commands ---------------------------------------------------------- Table B-1. Dr. Logo control and escape character commands Format: Character Effect (* indicates the character is valid within screen editor only.) Ctrl-A Moves the cursor to the beginning of the line. Ctrl-B Moves the cursor [B]ack one character; that is to say, it moves the cursor one position to the left. Ctrl-C * Exits the screen editor; updates Dr. Logo's workspace with definitions of all procedures and variables from the screen editor's buffer. Ctrl-D [D]eletes the character indicated by the cursor. Ctrl-E Moves the cursor to the [E]nd of the line. Ctrl-F Moves the cursor [F]orward one character; that is to say, it moves the cursor one position to the right. Ctrl-G Outside the screen editor, it immediately terminates the currently executing procedure. Inside the screen editor, it exits the screen editor without updating Dr. Logo's workspace, discarding any changes made during the screen editing session. Ctrl-H Deletes the character to the left of the cursor. Ctrl-I [I]nserts a tab (three spaces). Ctrl-J (No effect.) Ctrl-K [K]ills the remaining line; that is to say, it deletes all characters right of the cursor to the end of the line. Deleted characters are stored in buffer. Ctrl-L Outside screen editor, displays a full graphic screen, devoting the monitor to graphics. Inside screen editor, it readjusts the display so that the line currently indicated by the cursor is positioned at the center of the screen. If the cursor is less than 12 lines from the beginning of the buffer, the screen editor simply beeps when Ctrl-L is pressed. Ctrl-M Generates a Carriage Return. Ctrl-N Moves the cursor to the [N]ext line; in the screen editor, the cursor moves down one line towards the end of the buffer. Ctrl-O [O]pens a new line. In the screen editor, it is equivalent to pressing Enter followed by Ctrl-B. Ctrl-P Moves the cursor to the [P]revious line; the cursor moves up one line towards the beginning of the buffer. Ctrl-Q Generates the [Q]uoting character ("\") that makes Dr. Logo treat a delimiter character as a literal character. Delimiter characters are [ ] ( ) " : ; = < > + / ^ Ctrl-R (No effect.) Ctrl-S Displays a [S]plitscreen; opens a text window on the graphic screen. Ctrl-T Displays a full [T]ext screen, devoting the monitor to text. Ctrl-U (No effect.) Ctrl-V * Displays the next screen full of text in the screen editor's buffer, the next 24 lines towards the bottom of the buffer. Ctrl-W Interrupts the scrolling of a text display; [W]aits until the next keystroke to continue scrolling the display. Ctrl-X (No effect.) Ctrl-Y [Y]anks text from the buffer; that is to say, it redisplays the line most recently stored in the buffer by an Enter or a Ctrl-K keystroke. Ctrl-Z Interrupts the currently executing procedure; displays a pause prompt to allow interactive debugging. Enter "co" to continue the execution of the interrupted procedure. ESC-V * Displays the previous screen full of text in the screen editor's buffer, the previous 24 lines towards the beginning of the buffer. ESC-< * Positions the cursor at the beginning of the screen editor's buffer. ESC-> * Positions the cursor at the end of the screen editor's buffer. EOF DRLRMC.WS4 (= "Dr. Logo Reference Manual", Appendix C) ---------- (Retyped by Emmanuel ROCHE.) Appendix C: Functional command list ----------------------------------- Word and list processing ------------------------ ascii word butfirst, bf object butlast, bl object char n count object emptyp object equalp object object first object fput object object item n object last object list object object (...) listp object lowercase, lc word lput object object memberp object object numberp object piece n object proclist quote object sentence, se object object (...) shuffle list uppercase, uc word where word word word (...) wordp object Arithmetic operations --------------------- abs n arctan n cos degrees_n degrees radians_n exp n int n log n log10 n pi product n n (...) quotient n n radians degrees_n random n remainder n n rerandom round n sin degrees_n sqrt n sum n n (...) tan degrees_n + a b - a b * a b / a b ^ a b Logical operations ------------------ and pred_exp pred_exp (...) not pred_exp or pred_exp pred_exp (...) = a b < a b > a b Variables --------- local varname (...) make varname object name object varname namep word thing varname Defining procedures ------------------- copydef new_procname old_procname defined procname defin_list definedp object end primitivep object text procname to procname <inputs> Editing ------- edall <pkgname | pkgname_list> edit, ed <name | name_list> edns <pkgname | pkgname_list> edps <pkgname | pkgname_list> Text screen ----------- cleartext, ct cursor print, pr object (...) setcursor coord_list show object textbg n textfg n textscreen twoscreen type object (...) Graphic screen -------------- background, bg clean clearscreen, cs dot coord_list fence fullscreen pen pencolor, pc pendown, pd penerase, pe penreverse, px penup, pu setbg n setpc n setpen list setsplit n splitscreen turtletext, tt object (...) window wrap Graphic movement ---------------- back, bk distance_n forward, fd distance_n heading hideturtle, ht home left, lt degrees_n pos right, rt degrees_n setheading, seth degrees_n setpos coord_list setx n sety n shownp showturtle, st towards coord_list xcor ycor Workspace management -------------------- bury pkgname | pkgname_list erall <pkgname | pkgname_list> erase procname | procname_list ern varname | varname_list erns <pkgname | pkgname_list> erps <pkgname | pkgname_list> follow procname procname nodes noformat noprim package pkgname name | name_list pkgall pkgname po procname | procname_list poall <pkgname | pkgname_list> pons <pkgname | pkgname_list> popkg poprim pops <pkgname | pkgname_list> potl pots <pkgname | pkgname_list> recycle unbury pkgname Property lists -------------- glist prop <pkgname | pkgname_list> gprop name prop plist name pprop name prop object pps <pkgname | pkgname_list> remprop name prop Disks ----- copyd dest_d: source_d: defaultd initd d: n resetd <d:> setd d: spaced <d:> Files ----- changef new_fname old_fname copyf dest_fname source_fname erf fname getfs <d:> load fname save fname <pkgname | pkgname_list> Keyboard -------- fkey n instr_word keyp readchar, rc readlist, rl readquote, rq Printer ------- copyoff copyon printscreen Sound, lightpen and joystick ---------------------------- tones note_list lpen lpenp buttonp paddle_n paddle n Conditionals and flow of control -------------------------------- bye co <object> go word if pred_exp instr_list <instr_list> iffalse, iff instr_list iftrue, ift instr_list label word output, op object repeat n instr_list run instr_list stop test pred_exp wait n Error handling and debugging ---------------------------- catch name instr_list debug error nodebug notrace <procname | procname_list> nowatch <procname | procname_list> pause throw name trace <procname | procname_list> watch <procname | procname_list> EOF DRLRMD.WS4 (= "Dr. Logo Reference Manual", Appendix D) ---------- (Retyped by Emmanuel ROCHE.) Appendix D: Glossary -------------------- address Location in memory. ambiguous file name File name containing a wildcard character. In Dr. Logo, the wildcard character is a question mark ("?"). An ambiguous file name is used to access one or more files. For example, getfs "z? displays all file names that begin with the letter z. You can put the ? after any number of characters or as the only character, but the ? must be the last character in a file name. A file name cannot contain more than eight characters. See wildcard character. artificial intelligence Imitation of human-like information processing performed by a computer. ASCII Acronym for American Standard Code for Information Interchange. ASCII is a standard code for the computer representation of the numbers, letters, and symbols that appear on most keyboards. assembly language Human readable form of machine language. See machine language. backup or back-up Duplicate copy of data to be used in case the original is lost, destroyed, or accidentally altered. The process of duplicating a disk or file. BASIC Programming language that is widely used in microcomputers because of its English-like structure and ease of use. BASIC is an acronym for Beginner's All-purpose Symbolic Instruction Code. bit Fundamental unit of information that a computer understands. Abbreviated from Binary digIT. A bit can have one of two values, 0 or 1, meaning off or on, respectively. See byte. boot Act of starting up a computer system. buffer Area of memory that temporarily stores information during the transfer of information. bug Error in a procedure that prevents the procedure from executing as expected. byte Unit of memory or disk storage that usually contains eight bits. In ASCII code, each character is represented by one byte. cathode ray tube, CRT Picture tube that shows information being entered or output from the computer; functionally similar to those used in standard televisions. Commonly abbreviated CRT; also referred to as the monitor. cell See character cell. central processing unit, CPU Brain of the computer, commonly abbreviated CPU. Your IBM Personal Computer contains an Intel 8088 CPU, an integrated circuit that contains an arithmetic/logic unit that controls and manipulates the flow of information and its storage in memory. character Single letter, number, symbol, space, or punctuation mark. A character is usually stored in one byte of the computer's memory, or on disk. character cell Unit of space on the monitor that can hold one character. A cell is located at the intersection of each horizontal row and each vertical column. There are 1,000 character cells on a graphic display, and 2,000 character cells on a text display. Dr. Logo lets you control the background color and foreground color of each character cell on the graphic and text display. code Sequence of expressions written in a programming language that instructs the computer to perform a task. color monitor Output device that allows you to see the visual field of both the graphic screen and the text screen. command Instruction that makes Dr. Logo initiate an action. comments Remarks or explanatory notes set off from the rest of a procedure's definition by a semicolon (";"). compiler Language translator that interprets the text of a high-level language, like BASIC, into machine language code (1s and 0s) understandable to the computer. concatenation Joining of two or more objects together, end to end. For example, the primitive word outputs a single word made up of multiple inputs, as in word "sun "shine outputs "sunshine". constant Object, word, number, or list with a value that does not change when a procedure runs. control character Non-printing character combination that sends a simple command to Dr. Logo. To enter a control character, hold down the control (Ctrl) key, and press the specified character key. CP/M Operating system controlling the operation of Dr. Logo. CP/M stands for Control Program for Microcomputers. CPU See Central Processing Unit. crash Severe hardware or software malfunction. A head crash, for example, generally causes an irretrievable loss of the data on a disk. CRT See Cathode Ray Tube. cursor Blinking underline symbol on the text display. The cursor designates the position where the next keystroke at the keybaord has an effect. As you type, the cursor automatically advances. You can also move the position of the cursor with the cursor control keys located on the numeric key pad, the tab key ("-- >|"), and the backspace key ("<--"). On the graphic display, the turtle designates the point of action. data Information that is created, changed, or stored by the computer. debug Process of locating and correcting errors in a procedure. default Value supplied in the absence of user input. For example, when you start your computer system, drive A: is the default drive. Dr. Logo looks for files on the disk in the default drive, unless you specify another drive. delimiter Blank space or any of these special characters used to set another character, word, or number off from the next: [ ] ( ) ; < > + - * / ^. directory List of the contents of the disk. Use the getfs primitive to display a list of all the Dr. Logo file names on a data disk. disk Magnetic media used to store information. Sometimes called diskette. Programs and information are stored and retrieved like music on a record. The term diskette usually refers to floppy disks 5 1/4 or 8 inches in diameter. The term disk can refer to a diskette, a removable cartridge disk, or a fixed hard disk. disk drive Peripheral device that stores and retrieves information on disks. display Visual field of a screen, or to show the contents of the screen on the monitor. double sided Disk format that stores information on both sides; a disk drive that can read and write on both sides of a double-sided disk. Dr. Logo Digital Research's version of Logo, a programming language with extensions that make it suitable for commercial and academic applications. edit Process of adding, modifying, or deleting text in the definition of a user-defined procedure. editor Utility program that allows you to add, modify, or delete information from a text screen. See also line editor, procedure editor, and screen editor. element Single piece of an object. For example, a numeral is an element of a number, a character is an element of a word, and a word is an element of a list. end Special word that indicates the conclusion of a procedure's definition. The word "end" must stand alone on the last line of a procedure. enter Act of transmitting information to the computer. The computer does not recognize or process any information typed at the keyboard since the last prompt, until you press the Enter key ("<--+"). The Enter key on an IBM Personal Computer is the equivalent to a Carriage Return ("RETURN") on a standard typewriter keyboard. evaluate Process Dr. Logo goes through to execute an expression. executing a procedure See running a procedure. expression In Dr. Logo, an expresion is a procedure name followed by its inputs. file Collection of information on a disk. file name Name you assign to a file. The file name can consist of up to eight alphabetic or numeric characters. The first character in a file name must be alphabetic. floating point Method Dr. Logo uses internally to express numbers that have a decimal point that can shift to the left or right. floppy disk Flexible magnetic disk used to store information. A floppy disk is a thin piece of mylar, coated with magnetic particles. The disk drive causes the floppy disk to rotate inside its paper jacket. Floppy disks come in two sizes: 5 1/4 and 8 inches in diameter. flowchart Graphic diagram that uses special symbols to indicate the input, processing, output, and flow of a procedure. function Operation or specific task that is called into action by referencing the procedure by name. The result of a function is always a single value. See operation. function keys Ten multiple-purpose keys located along the left side of the keyboard, labeled F1 through F10, that you can program to recall command lines of up to 16 characters. Press the Enter key to execute the recalled command line. graphic displays Visual representations that illustrate, map, or plot mathematical curves, diagrams, graphs, or charts. Dr. Logo allows you to draw graphic designs with the turtle. graphic screen Construct in memory where graphic data is stored that can extend beyond the range of your monitor. You can display the visual field of the graphic screen on a color monitor. Dr. Logo allows you to draw graphic designs on the graphic screen with the turtle. graphic window Visual display of the graphic screen on a color monitor; that portion of the monitor dedicated to the graphic screen. Dr. Logo's splitscreen primitive allows you to have both text and graphic windows on the same color monitor. hardware Physical components of a computer, such as the central processing unit, random access memory, disk storage devices, monitor, keyboard, printer, lightpen, paddle, or joystick. high-level language Computer language written in procedural form that is easily comprehensible by humans. Many machine language instructions are generated for each high-level expression. Dr. Logo is a high- level language. infix operation Operations where the primitive name or identifier is positioned between its inputs, as in a + b. initialize Act of preparing or formatting a disk, in order to read and write information on it. input Object that a procedure requires to complete its task; information entered into the computer by an operator typing at the terminal or by a procedure reading from the disk, or to enter such information. input device Mechanism that accepts information from the outside world and converts that information into a form that the computer can use. A keyboard is an input device. input/output devices Combination of input and output devices. Commonly abbreviated I/O devices. integer Positive or negative whole number with no decimal point. interface Object that allows two independent systems to communicate with each other, as an interface between hardware and software in a microcomputer. interpreter Computer program that evaluates each line as it is typed at the keyboard, and each line of a procedure every time it is run. Dr. Logo is an interpreted computer programming language. interpreter prompt Question mark ("?") signaing that Dr. Logo is expecting you to type something at your keyboard; the interpreter is waiting for input. I/O Abbreviation for input/output. This term commonly refers to combinations of input and output devices. jacket Stiff paper container that holds a floppy disk. joystick See paddle. kilobyte 1024 bytes, commonly denoted as 1K. language System of words and symbols used to write programs that communicate with a computer. level number Number enclosed in square brackets ("[" and "]") that precedes each line displayed by the trace and watch primitives. The number indicates the position of the procedure on the stack. See stack. lightpen Input device that allows you to interact with the computer without the keyboard. The lightpen sends a screen location to the computer when you touch the screen's surface with the tip of the lightpen. line editor Dr. Logo interpreter's utility that allows you to modify the current line of text without erasing and retyping the entire line. Dr. Logo allows you to use certain control characters or function keys to move the cursor left and right over the current line of text to make modifications before you press the Enter key. LISP Programming language derived from the words LISt Processing. LISP dominates artificial intelligence programming because of its powerful symbolic and list processing capabilities. Logo evolved from LISP. list Type of object used as input to a Dr. Logo procedure. A series of objects (words, numbers, or lists) separated by spaces and enclosed in square brackets ("[" and "]"). load To move procedures or information from permanent storage on the disk into the computer's memory buffer or workspace. logical operator Mathematical symbols representing equals ("="), less-than ("<"), or greater-then (">") as well as the primitives "and", "not", and "or" that are used in predicate expressions; expressions that evaluate to either TRUE of FALSE. Logo Name of a programming language derived drom the Greek word logos, which means word. Logo is a computer language that evolved from LISP and is designed to teach the fundamentals of computer programming. machine language Sequence of instructions to the machine, written in terms of 1s and 0s, and generally not understandable by humans. See bit. megabyte One million bytes, or 1024K bytes. See kilobyte. memory That part of a computer system that temporarily stores information. Also called random access memory (RAM) or working storage. Dr. Logo automatically loads into memory when you start up your system. Once Dr. Logo is loaded, it allocates part of memory for your workspace. microprocessor Miniaturized integrated circuit usually on a silicon chip that is the brain of the microcomputer. monitor Output device that displays the visual field of your graphic or text screen. A color monitor displays both graphic and text screens; a monochrome monitor displays only text. monochrome monitor Output device that displays the text screen. name Type of object used as input to a Dr. Logo procedure. A special word that identifies a procedure, a variable, a package, a file, or a disk. number Type of object used as input to a Dr. Logo procedure. In Dr. Logo, a number is a kind of word and can be used as a variable name if it is preceded by a quotation mark, as in "8. A number cannot be used as the first or only character in a procedure name. In arithmetic operations, you can input negative or positive decimals numbers with up to 15 significant digits. numeric constant Real or integer quantity that does not change as the procedure is run. numeric pad Separate set of keys, arranged like a 10-key adding machine, located on the right of the IBM Personal COmputer keyboard. Provided because they are useful for entering large amounts of numeric information. Press the NUM LOCK key, located above the numeric pad, to make the keys function as cursor control keys. object Type of input to a Dr. Logo procedure. A Logo object can be a word, a number, a list, or anything that is not a procedure name. Variables can represent objects. operation Procedure that outputs an object, or a mathematical process such as addition, multiplication, subtraction, or division. In Dr. Logo, an operation is equivalent to a function. operating system Master program that supervises the execution of other programs, and manages the computer system's resources. An operating system provides an orderly input/output environment between the computer and its peripheral devices. Dr. Logo runs under the CP/M operating system, which is compatible with many different computer systems. optional input Inputs that are not required. In the primitive expression syntax descriptions, optional inputs are enclosed in angle brackets ("<" and ">"). output Object returned to the caller by a procedure; data that the processor sends to the console, printer, or disk after processing is complete. To send information to the console, printer, or disk. The computer outputs the requested object or data. output device Mechanism by which a computer transfers its information to the outside world. The printer is an output device. package Group of related procedures or variables. Packaging helps you manage your workspace. When you organize your procedures and variables into packages, you can display, edit, save, or erase a whole group without affecting other procedures or variables in the workspace. paddle Input device that allows you to interact with the computer without the keyboard. Common on electronic computer games and also called a joystick. The coordinate scale that the paddle or joystick sends to the computer depends on the kind of device you purchase. Dr. Logo supports up to two paddles or joysticks, each with two buttons. peripheral device Mechanisms that are external to the CPU. Terminals printers, disk drives, paddle (joystick), and lightpen are peripheral devices. permanent storage Location outside of the computer's memory where data can be stored, usually on disk. When you save a file, you copy the information from the workspace onto the disk. pixel Smallest element of a monitor's display; a point within a character cell. Also referred to as a dot. A turtle step, as in the command forward 1, is equivalent to one pixel. precedence Order in which Dr. Logo processes arithmetic operations. predicate expression Expression that contains a logical operator and outputs either TRUE or FALSE. A predicate expression can be a type of input to a Dr. Logo procedure. prefix operation Operations where the primitive name or identifier precedes the inputs, as in - a b, or print [Hi there!]. primitives Procedures, operations, or commands that make up Dr. Logo; the built-in procedures. printer Peripheral device used to put computer information on paper. printout Printed material or listing produced by the printer. procedure A series of expressions that tell Dr. Logo how to perform a task. procedure editor Dr. Logo interpreter's utility that allows you to teach Dr. Logo a new task, that is to say, to define a new procedure. The procedure editor is identified by the greater-than sign (">"), a prompt that appears when you enter the word "to" at the interpreter's question mark prompt ("?"). All the line editor's control character commands function within the procedure editor. procedure editor prompt Greater-than sign (">") that tells you Dr. Logo is expecting you to enter a procedure definition line. Dr. Logo does not immediately evaluate the expressions typed at the > prompt. program Complete set of instructions designed to tell the computer to perform a specific task. To define a Dr. Logo procedure. prompt Cue displayed on the monitor telling the user that Dr. Logo is expecting input. A prompt can be a symbol, such as ?, >, or !. Or a prompt can be a message, such as "Is this what you want (y/n)?". All prompts expect a response from the user. For example, when you see the ! prompt, you are extremely low on free nodes in your workspace. Your response should be to enter the primitive "recycle" to call the garbage collector. See interpreter prompt and procedure editor prompt. property Quality or attribute of an object, procedure, or package. property list List of property pairs that represent the qualities or attributes connected with an object, procedure, or package. Use the pprop primitive to assign both the Dr. Logo system properties and your own non-system properties. Use the plist primitive to display a property list. property name First member of a property pair; the label representing the quality or attribute of an object, procedure, or package. For example, the .BUR property name in a package name's property list signifies that the package is buried. property pair Two parts of a property. The first element of a property pair is the property name; the second element is its value. For example, in a procedure's property list is a property pair consisting of the property name .DEF and the value of .DEF, the actual definition of the procedure. property value Second member of a property pair; the qualities of or attributes connected with an object, procedure, or package. For example, the information following a .PAK property name in a property list is the property value, the name of the package to which this object belongs. RAM See random access memory. random access Process of reading or writing informaion in memory or on a disk in any order. random access memory Temporary memory location inside a computer. Also called working storage. Commonly abbreviated as RAM. Size of RAM is measured in kilobytes. random number Number selected by chance from a set of numbers. The random primitive returns a random number in Dr. Logo. read Process of transferring prestored information from a storage device, such as a floppy disk, into the computer's memory. Read-Only Attribute of a disk or a disk drive that allows you to read but not write to the disk or disk drive. Read-Only disk Attribute assigned to a disk that allows you to read from that disk, but not change it. To assign the Read-Only attribute to a 5 1/4 inch floppy disk, disable the Read-Write notch on the upper left side of the disk by placing a sticker over it. Read-Only disk drive Attribute assigned to a disk drive that allows you to read any file on the disk but prevents you from adding a new file, erasing a file, changing a file, or renaming a file. A drive has the Read-Only attribute when a new disk is inserted. Use the primitive resetd to give the drive a Read-Write capability. Read-Write Attribute of a disk or a disk drive that allows you to read from and write to the disk or the disk drive. A 5 1/4 inch floppy disk can be set to Read-Write by cutting out the Read-Write notch on the upper left corner of the disk. A drive can be set to Read-Write by entering the resetd command after inserting a new disk. real number Numeric value specified with a decimal point, internally represented in floating point notation. reserved word Keyword that has specific meaning to a given language or operating system. In Logo, the keywords are called "primitives". A reserved word cannot be used as a procedure or variable name, unless you have set the system variable REDEFP to TRUE. running a procedure Process of Dr. Logo evaluating and performing the expressions in a procedure. save To transfer information from random access memory into permanent storage on the disk. screen Construct in memory where text or graphic data is stored. Dr. Logo supports two kinds of screens: a text screen and a graphic screen. A color monitor can display both kinds of screens, and a monochrome monitor can display only the text screen. screen editor Dr. Logo utility that allows you to define a procedure or modify a procedure without retyping the complete definition. In the screen editor, you can use special screen editing control characters that enable you to move from line to line in a procedure, as well as all of the line editor's control character commands. You can start the screen editor by typing the commands ed, edall, edps, or edns at Dr. Logo's ? prompt. single-sided Disk format that stores information on only one side; a disk drive that can read or write on only one side of a single-sided disk. sixteen-bit computer Computer system that is capable of processing information sixteen bits at a time, potentially twice as fast as an eight- bit system. Sixteen-bit systems can usually accomodate more RAM than eight-bit systems, making some applications more efficient. software Set of instructions that tells the hardware how to complete a particular task. Unlike hardware, software is not an electronic product, and does not perform any physical work. Software is a communication tool that allows you to interact with the hardware. splitscreen Display where a text window is opened on the graphic screen of a color monitor. stack Area in memory used by the interpreter to keep track of which procedure is currently running. store To save information. See save. superprocedure Procedure that is never called by any other procedure. You call a superprocedure into action by entering the procedure name at Dr. Logo's ? prompt. Use the potl primitive to display the names of superprocedures. syntax Format for entering an expression. syntax error Error that results from entering an expression that does not conform to the syntax rules. temporary storage See random access memory. terminal Input/output device consisting of a monitor and a keyboard. text screen Area in memory where text data is stored. You can display the visual field of the text screen on either a monochrome or color monitor. text window Visual display of the text screen on either a color monitor or a monochrome monitor; that portion of the display dedicated to the text screen. Dr. Logo's splitscreen primitive allows you to have both text and graphic windows on the same color monitor. toplevel Interpreter's prompt. When Dr. Logo displays a question mark ("?"), there are no procedures on the stack, and the level number is 0. trace Option used for debugging a procedure while it is running. The trace option displays the name of each procedure as it is called, and the name and value of each variable as it is defined. Trace allows you to observe the details of the procedure's execution without interruption. turtle Graphic symbol that functions as a cursor appearing on the Dr. Logo graphic screen. turtle graphics Dr. Logo's graphics environment. The Logo language allows you to draw on the graphic screen by directing the turtle's movement. As the turtle moves, it leaves a trace of its path on the screen. turtle step One pixel or dot on the IBM Personal Computer. user Person who operates a computer. user-friendly Quality of a piece of software that makes it simple for the inexperienced person to use. utility program Software tool that enables the user to perform certain operations. For example, the editor is a utility program that enables you to add, change, and delete text in a Dr. Logo procedure. value Quantity expressed by an integer or real number; the object assigned to a variable or property name. variable Name to which Dr. Logo can assign an object as a value. A variable can be thought of as a container that can hold a value. visual field Portion of the screen displayed on the monitor. watch Option used for debugging a procedure while it is running. The watch option displays the procedure's name and the expression that the interpreter will evaluate next, one line at a time. It waits for you to press the Enter key before it executes that line. This feature allows you to interact with the interpreter or edito during the execution of a procedure. wildcard character Question mark ("?") character that gives Dr. Logo a pattern to match when searching in a disk directory for a file name. A ? placed in a file name creates an ambiguous file name. See ambiguous file name. window Visual portion of the screen. See graphic window and text window. word Type of object used as input to a Dr. Logo procedure. A group of one or more consecutive characters separated from other characters on the line by a delimiter. working storage See random access memory. workspace Dr. Logo's temporary storage area for information, such as your procedures, variables, and property lists. EOF DRLRME.WS4 (= "Dr. Logo Reference Manual", Appendix E) ---------- (Retyped by Emmanuel ROCHE.) Appendix E: Getting Started --------------------------- This section quickly leads you through a complete session with Dr. Logo. It shows how to start up and shut off Dr. Logo, how to initialize a disk, define a Dr. Logo procedure, save and load files, specify the default drive, and back up your data disk and files. The beginning of this book explain why you must enter quotation marks and other punctuation; to keep this introduction brief, the explanations are not repeated here. To complete this session, simply type each of the examples exactly as it is shown, and then press the Enter key ("<--+"). If you make a typing error, use the backspace key ("<--") to correct it, or retype the line. Do not worry about mistakes; you can't hurt Dr. Logo or your computer with typing errors. If, while reading this section, you find a computer-related term you do not understand, you can find its definition in Appendix D, the glossary. E.1 Starting up Dr. Logo ------------------------ Your computer automatically loads Dr. Logo into memory when you turn on your computer. You can start up Dr. Logo in one of two ways, depending on whether your computer is powered OFF or ON. If the power is OFF ------------------- 1. Open the door of drive A: by lifting the load latch outwards. 2. Insert the Dr. Logo system disk with the label face up and the disk jacket seams underneath. Hold the label in your hand as you slide the disk into the slot. See Figure E-1. Figure E-1. Inserting a disk (not shown) 3. Close the disk drive door by pulling the load latch down. 4. Turn ON the printer, if you have one, the color monitor and monochrome monitor if you have one, and finally the computer system unit. (If you have just powered off, but want to use your computer again, you must count slowly to five before you power ON.) If the power is ON ------------------ 1. Insert the Dr. Logo system disk into drive A: and close the door. 2. Hold down the Ctrl and Alt keys, and press the Del key. Then, release all three keys. This sequence is called system reset. See Figure E-2. Figure E-2. System keyboard (not shown) In either start sequence, wait a moment while the system does some self-testing. Watch for the red light on drive A: to flash, and listen for the drive to read Dr. Logo from the system disk into your computer's memory. While Dr. Logo is being loaded, it displays the following message on your monitor: +---------------------------------------+ | Welcome to Dr. Logo, Version V.V | | Copyright (C) 1983, Digital Research | | Pacific Grove, California | | | | Please Wait | | | | | | | | | +---------------------------------------+ Figure E-3. Dr. Logo banner The version number, represented above by V.V, tells you the major and minor revision level of the Dr. Logo version that you own. After this greeting disappears, a question mark ("?") prompt and the flashing underline ("_") display on your text screen. The question mark tells you that Dr. Logo is waiting for you to type something at your keyboard. The underline tells you where the next character you type will appear. Once in memory, Dr. Logo allocates a part of memory for your workspace. When you start Dr. Logo, the workspace is empty, ready for you to type in new procedures or load previously saved procedures from a disk. E.2 Defining Dr. Logo procedures -------------------------------- A procedure is a list of instructions that tells Dr. Logo how to do a task. Dr. Logo performs the task when you enter the procedure's name. The list of instructions is the definition of the procedure. You use primitives and previously-defined procedures to define a new procedure. For example, here is how to enter a procedure that makes Dr. Logo draw a square on the graphic screen with the turtle. Type the following: ?to square >repeat 4 [forward 60 right 90] >end square defined ? When you type the statement "to square", Dr. Logo responded with a > prompt on the next line. The special word "to" signals to Dr. Logo that you are starting to define a new procedure. The greater-than sign (">") indicates that Dr. Logo is remembering your instructions as a procedure definition. After you define the procedure, you can make Dr. Logo perform the new task by typing the procedure name at Dr. Logo's ? prompt and pressing the Enter key. For example, type ?square ? cs stands for clearscreen, and erases the square from the screen. You can teach Dr. Logo to draw a triangle as follows: ?cs ?to triangle >right 45 forward 35 >right 90 forward 35 >left 225 forward 50 >end triangle defined ?triangle ? Now, you can use the triangle and the square procedures in the definition of another procedure. For example, ?cs ?to draw.house >square >forward 50 >triangle >end draw.house defined ?draw.house ? You can look at the names of the procedures you have defined by asking Dr. Logo to print out titles, pots in short: ?pots to square to triangle to draw.house ? When you turn off your computer, everything in your workspace disappears. If you were to turn off your computer now, these procedures would be lost. To be able to use them later, you must save them on a disk. But, before you try to save your procedures, remember that your Dr. Logo system disk is write-protected. That means you can only read Dr. Logo from it, and cannot save procedures on it. You can take your Dr. Logo system disk out of the A: drive as soon as Dr. Logo is loaded. Store your system disk in a safe place, away from heat and magnetic devices such as telephones and vacuum cleaners. Before you can save procedures, you must create a data disk, a disk that can store procedures in files, and insert it in a drive. A disk fresh from the box is not ready to store files; you must initialize (format) a new disk before you can read or write any data on it. E.3 Initializing a disk ----------------------- You must always initialize a disk that is fresh from the box. If you have an old disk that you want to reuse, you can initialize the disk to remove all the old data on the disk and reformat it, as if it were new. Before you begin ---------------- 1. Make sure that the read/write notch is cut out of the upper left edge of the disk jacket. 2. Check to see if you have single- or double-sided disk drives. If you have single-sided disk drives, you must initialize your disks to single-sided format. A double-sided drive can handle either single- or double-sided disks. You will need to initialize two new disks, one to be your data disk and the other to be your back-up disk. If you have a one-drive system ------------------------------ 1. If you have not already done so, remove your Dr. Logo system disk, and store it in a safe place, away from heat and magnetic devices, such as telephones and vacuum cleaners. Insert the disk to be formatted in drive A: and close the door. 2. If you have a single-sided drive, you must initialize the disk to single-sided. Type ?initd "a: 1 Dr. Logo displays the following prompt: I will erase the diskette in drive A and will make it single-sided. Is this what you want (y/n)? If you have a double-sided drive, you can initialize the disk to double-sided. Type ?initd "a: 2 Dr. Logo displays the following prompt: I will erase the diskette in drive A and will make it double-sided. Is this what you want (y/n)? 3. Type y (yes) to format the disk. Type n (no) if you have not removed the Dr. Logo system disk or, for some other reason, wish to return to Dr. Logo's ? prompt. After you type y, watch for the drive's red light to flash, and listen as Dr. Logo formats the disk. When the formatting is complete, Dr. Logo's ? reappears. 4. Format a second disk, repeating steps 1 through 3, for a back-up disk. If you have a two-drive system ------------------------------ 1. You can leave your Dr. Logo system disk in drive A:. Insert the disk to be formatted in drive B: and close the door. 2. If you have single-sided drives, you must initialize the disk to single-sided. Type ?initd "b: 1 Dr. Logo displays the following prompt: I will erase the diskette in drive B and will make it single-sided. Is this what you want (y/n)? If you have double-sided drives, you can initialize the disk to double-sided. Type ?initd "b: 2 Dr. Logo displays the following prompt: I will erase the diskette in drive B and will make it double-sided. Is this what you want (y/n)? 3. Type y (yes) to format the disk. Type n (no) if you wish to return to Dr. Logo's ? prompt. After you type y, watch for the B: drive's red light to flash, and listen as Dr. Logo formats the disk. When the formatting is complete, Dr. Logo's ? reappears. 4. Format a second disk, repeating steps 1 through 3, for a back-up disk. E.4 Saving Dr. Logo files ------------------------- Saving a file means copying the contents of your workspace to permanent storage on the disk. 1. If you have a single drive system with a data disk in drive A:, type the following command to save the contents of the workspace in a disk file. ?save "home If you have a two-drive system with a data disk in drive B:, type ?save "b:home You have now made a copy of your three procedures square, triangle, and draw.house in a file named "home" on the disk in either drive A: or drive B:. Your procedures are still in Dr. Logo's workspace, as you can see with a pots command. ?pots to square to triangle to draw.house ? 2. To verify that Dr. Logo has saved your procedures, ask it to show you the names of Dr. Logo files on the disk. ?getfs [HOME] Or, if you saved the file on drive B:, type ?getfs "b: [HOME] 3. Now that you have saved your procedures, you can erase them from your workspace with confidence they can be restored. Type ?erall Now, to verify that the workspace has been erased, ask Dr. Logo to print out the titles of procedures in the workspace by typing ?pots ? Dr. Logo displays only the ? prompt, because nothing is in the workspace. E.5 Loading Dr. Logo files -------------------------- To load a file means to move the procedures or other information from permanent storage on the disk into the Dr. Logo workspace. To load a file, you must have saved it on the disk, and be able to see its name with a getfs command. 1. To load the file you just saved, type ?load "home Or, if you saved the file on drive B:, type ?load "b:home Listen ad Dr. Logo moves the procedures in the file from the disk into the workspace, and displays the following list on your screen: square defined triangle defined draw.house defined 2. Verify that the procedures are in your workspace by executing them, or by using pots to print out their titles. ?draw.house ?pots to square to triangle to draw.house ? E.6 Specifying the default drive -------------------------------- When you do not specify a drive in a disk command like save, load, or getfs, Dr. Logo automatically looks for files, or writes files, on the disk in the default drive. When you start Dr. Logo, A: is the default drive. If you have a one-drive system, you only have drive A:, and do not need to specify a drive name in any of your commands. If you have two drives and leave your system disk in drive A:, enter the following commands to change yor default drive to B:. 1. Determine which drive is the default drive by typing ?defaultd A: 2. Change the default drive to drive B: by typing ?setd "b: ?defaultd B: 3. To verify that Dr. Logo now looks on drive B: for files, type ?getfs [HOME] E.7 Backing up a disk --------------------- To back up a disk means to make a duplicate copy of its contents. Professional programmers avoid losing programs by making copies of valuable disks and files. If your working copy is accidentally damaged or erased, you can restore it from the back-up copy. The frequency of making copies varies with each programmer, but as a general rule make a copy when it would take 10 to 20 times longer to re-enter the information than to make the copy. To make a back-up disk, you need an initialized or formatted disk on which to write. Make sure your data disk and your back- up disk are the same format: double-sided or single-sided. If you have a one-drive system ------------------------------ 1. Start with the data disk that you plan to copy in the drive. This is your source disk. 2. To start the copying process, type ?copyd "a: "a: Figure E-4. System unit with one drive (not shown) If you have a two-drive system ------------------------------ 1. Insert the back-up disk into drive B: and the data disk into drive A:. 2. To make an exact, track-to-track copy of the disk in drive A: onto the disk in drive B:, type ?copyd "b: "a: Dr. Logo displays the following message before it begins to copy: I will copy from the diskette in drive A to the diskette in drive B, erasing any existing data on the diskette in drive B. Is this what you want (y/n)? 3. Type y (yes) to copy the data disk onto the back-up disk. Type n (no) to return to Dr. Logo's ? prompt without making the copy. If you type y, watch for the red lights to flash back and forth from drive A: to drive B:, and listen as the data is transferred from one disk to the other. Figure E-5. System with two drives (not shown) E.8 Copying a file ------------------ Another way to back up a file is to make a copy of just that file, without making a copy of the entire disk. If you have a one-drive system ------------------------------ 1. Start with the data disk containing the original file in the drive. This is called your source disk. 2. To copy the file, type ?copyf "home "home 3. After Dr. Logo displays a message, remove the source data disk, and insert your back-up data disk into the drive. If you have a two-drive system ------------------------------ 1. To copy a file from the data disk in drive A: to the back-up disk in drive B:, type ?copyf "b:home "a:home 2. Verify that the file has been copied with a getfs command. ?getfs "b: [HOME] E.9 Shutting off Dr. Logo ------------------------- Before you turn off the power to your computer, be sure to check that you have performed the following steps: 1. Save the contents of your workspace on disk, so that you can load it later. 2. Make back-up copies of your files on a back-up disk. 3. Take your disks out of the drives. NEVER turn off your system with the disk engaged in the drive; this can permanently damage your disk. 4. Turn the power switches on your monitor, printer, and system unit to OFF. EOF