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ODYSSEY2 COMPUTER INTRO BY MAGNAVOX Contents 2. In The Beginning 11. The World of the Computer 20. Creepy Crawler 28. Creepy Crawler Version II 29. The Roll Mode - Your Program Trouble Shooter 30. Addition*Program A 35. Addition*Program B 40. Addition*Program C 46. One Digit Multiplication 52. One Digit Division 62. Area Problems Using "Go to Subroutine" and "Return" 71. One Digit Addition Flash Card 74. Three Ways to Enter and Output a Letter 76. Six Letter Guess 80. Message 87. Operating Mode Review 92. Glossary of Frequently Used Computer Terms 100. Instruction Sets 104. Program Sheets this gatefold will provide you with an electronic road map - please keep it open as you work with your Odyssey2 computer Key Codes Key Hex Decimal Code Code Equivalents ------------------------- 0 00 00 1 01 01 2 02 02 3 03 03 4 04 04 5 05 05 6 06 06 7 07 07 8 08 08 9 09 09 A 20 32 B 25 37 C 23 35 D 1A 26 E 12 18 F 1B 27 G 1C 28 H 1D 29 I 16 22 J 1E 30 K 1F 31 L 0E 14 M 26 38 N 2D 45 O 17 23 P 0F 15 Q 18 24 R 13 19 S 19 25 T 14 20 U 15 21 V 24 36 W 11 17 X 22 34 Y 2C 44 Z 21 32 [incorrect] Blank 0C 12 : 0A 10 $ 0B 11 Clear 2E 46 ? 0D 13 . 27 39 + 10 16 - 28 40 * 29 41 ./. 2A 42 = 2B 43 Enter 2F 47 Internal Flow [Illustration shows a box labeled Control Unit, boxes hanging off it labeled Accumulator, Program Counter, Subroutine Return Address Register, ALU, and Registers 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F. Also, arrows pointing to and from the Control Unit and three boxes Labeled Memory (ROM) Instructions and Constants, Keyboard, and Symbol/Sound Generator. Also, an arrow going from Symbol/Sound Generator to a box labeled TV Screen.] Keyboard [Illustration of the keyboard] Computer Intro is not for everyone - but if you're up for a rewarding mental challenge, here is a fascinating entry point into a complex and highly technical subject. The cartridge turns your Odyssey2 into a very special kind of computer. It won't balance your checkbook or do your income tax or plot the course of a spaceship to Mars. But it will giveyou some idea of how those computers do their work. You will begin to understand how a computer "thinks" and even begin to think like a computer "thinks." The initial orientation and explanation are deliberately couched in the most simplistic of terms. They don't assume anything more on your part than a working knowledge of basic arithmetic. After a brief explanation of how computers work and what they are made of - you will start getting "hands on" experience and will learn by doing. You will learn how to enter a program - the first stop in learning how to actually write your own. The gatefolds in the front and back of the manual provide you with electronic road maps. Keep these references in front of you and you will clearly understand what's going on and how computers really compute. In The Beginning In the beginning, there were ten fingers - then a prehistoric Einstein discovered his toes and man could count up to twenty. The oldest computing device we know of is the abacus. It was first used in China in the sixth century B.C. The very first digital computer was designed by Charles Babbage in the 1830's. It was more than a calculator. Babbage designed it to be programmable, and it would have been able to perform any arithmetic or logic calculation. It was designed to use punched cards for entering data and instructing the machine with mathematical commands. [Illustration shows an abacus. Caption: Chinese Abacus] [Illustration of a person using an abacus] [Illustration of a Babbage computer. Caption: Babbage computer] There were two problems. Problem one. Babbage's elaborate drawings called for a building the size of a Dickensian shoe factory to house his "analytical engine." Problem two. Babbagge died before the machine could be built. The first practical programmable computer was built in a basement at Harvard University during World War II by IBM. It weighed 35 tons! This machine used an exotic combination of electronic, electrical and mechanical gear to do its arithmetic. The instruction program was stored on a punched paper tape that unreeled automatically. Number were entered into the machine on a panel covered with 1,440 dials! The first all-electronic computer was built at the University of Pennsylvania shortly after the war ended. ENIAC (Electronic Numerical Integrator and Computer) was 1,000 times faster than its predecessor. But it filled a room 30 feet wide and 50 feet long. Its 18,000 vacuum tubes were connected by about a half-million soldering points. Today, everything that ENIAC could do and far more is performed by a device slightly smaller in size. It is less than one quarter of an inch square - and can make more than one million electronic decisions every second. It is called a semiconductor. It is possible for one semiconductor in one of its newest forms - the microprocessor - to account for more than 310 trillion separate functions. [Illustration of a bunch of gears. Caption: Detail section of the Babbage computer] And this is only the beginning! If computer technology continues to develop at its present rate, one of these chips will be able to store about a quarter-million bits (the smallest unit of computer information) in its memory within a few years. Ten years from this point, there will be hips capable of remembering a million bits of information. By 1990, the number of logic or decision-making computer circuits on these one quarter inch chips are expected to number a quarter of a million. Today's large computers, selling in the one million dollar range and as big as several filing cabinets, contain only about 10,000 logic circuits and a main memory capacity of a few million bits. [Picture of a circuit board] [Picture of a few buttons, with one lit button labeled READY. Superimposed is a green sine wave] [Picture of a chip, with some forceps reaching to grab something.] As microprocessor technology progresses, computers may be developed that understand human speech. It is even possible that they can be taught to read handwriting! The microprocessor in your Odyssey2 is infinitely more sophisticated than the mathematical marvels that were the state of the art in the forties and fifties. The technology of the microprocessor is unquestionably going to revolutionize the way the world works - and the way you'll live. A computer will control your car's automatic transmission and fuel injection system. A computer will monitor fire and burglar alarm systems in your home. The lights in your home will be computerized. So will the locks on the doors and windows. [Picture of another circuit board] [Picture of a display tube with a hand operating a control on it] A computer will even water the lawn. A computer will do your shopping from the house - and pay your bills without you writing checks. Computers will simulate three dimensional space for architects to help them mentally walk around their houses before they're built. Computers will alert doctors to patient problems that would be imperceptible under today's circumstances. Computers will help composers hear their music as they're writing it - even if it's too complicated for them to play. Businessmen can have electronic simulations of their companies in their attache cases. We are really still just at the very beginning of the computer age. You have picked a very good time to get involved. [Picture of some sort of control panel, with an image of cars on a freeway double exposed on top of it] [Picture of a circuit board] The World of the Computer Is Strange and Wondrous Computers have already carried man to the moon - to Mars - and far beyond. They lie at the heart of fearsome weapons systems. They fly planes - monitor automobile engines - run factories - and even translate languages. All of these with the brain power of a good screwdriver. Congratulations! You have just completed your first lesson. You are much smarter than any computer at the present state of the art! For all of its awesome capabilities, the computer is nothing more than a rather simple-minded tool. But once you learn how to use it, you'll have more power at your command than Julius Caesar ever dreamed of. A computer has few basic talents. It can add - and it can move numbers around. A computer never forgets - and computers don't make mistakes. (If a computer churns out misinformation, there's a mistake in the program. Computers are utterly faithful in following instructions.) Big deal. Computers can't multiply, divide, or even subtract the way you do. But what a computer does do, it accomplishes with absolutely astonishing speed. Your Odyssey2 can make over 100,000 electronic decisions every second - and there are computers around that are more than ten times faster than that! To multiply, Odyssey2 simply adds number together at an incredible speed. To subtract, it moves numbers around in a special way so that adding them together will give the correct answer. This sounds like doing it the long way - but when you're that fast at addition, the juggling act becomes worthwhile. It's not all that hard to talk with a computer. It only understands two words. Yes - and no. Yes - means that an electrical pulse is tickling the computer's sensitivities. No - means that no electrical pulse is going through. The symbol for "yes" in computer language is 1. The symbol for "no" is 0. Once you have memorized 0 and 1, you have memorized the entire alphabet of the only language computers speak in any country of the world. This is called a binary system because there are only two symbols involved. It's sort of a code. Here's the key. Binary Numbers and Their Decimal Equivalents. 1=0001 5=0101 9=1001 13=1101 2=0010 6=0110 10=1010 14=1110 3=0011 7=0111 11=1011 15=1111 4=0100 8=1000 12=1100 16=0001 0000 Letters of the Alphabet and Their Binary Code Equivalents. Keyboard Letter Binary Decimal Hexidecimal A 0010 0000 32 20 B 0010 0101 37 25 C 0010 0011 35 23 D 0001 1010 26 1A E 0001 0010 18 12 F 0001 1011 27 1B G 0001 1100 28 1C H 0001 1101 29 1D I 0001 0110 22 16 J 0001 1110 30 1E K 0001 1111 31 1F L 0000 1110 14 0E M 0010 0110 38 26 N 0010 1101 45 2D O 0001 0111 23 17 P 0000 1111 15 0F Q 0001 1000 24 18 R 0001 0011 19 13 S 0001 1001 25 19 T 0001 0100 20 14 U 0001 0101 21 15 V 0010 0100 36 24 W 0001 0001 17 11 X 0010 0010 34 22 Y 0010 1100 44 2C Z 0010 0001 32[BAD] 21 Working with endless daisy chains of 0's and 1's would be more than tedious for the human brain - but the computer is really good at it. The inside of a computer is mainly a series of little electronic gates. 0 - the absence of an electrical pulse - leaves the gate open. 1 - the presence of an electrical pulse - closes the gate. And remember - the electronic gates in your Odyssey2 computer are opening and closing at the rate of 100,000 times every second. You will enter programs in your Odyssey2 through either the hexidecimal or assembler language (these will be explained later). The Odyssey2 will then change the data and instruction sets entered into binary language (1's and 0's) and store that information in the Memory and in the registers. The actual computing is done by the computer's Central Processing Unit (CPU). The CPU in your Odyssey2 is composed of the Accumulator (a working register which stores data temporarily); the Program Counter (a working register which locates and identifies the instruction sets and keeps them in order); the Registers (in which data, implemented by the programmer, is stored); the Sub-Routine Return Register (which is used with a certain instruction set); the Arithmetic Logic Unit (ALU); and the Control Unit. The Control Unit directs the flood of electronic traffic traveling through the computer and controls the data flow between the different components of the computer. For example, it regulates the flow of information between the Memory and Arithmetic Logic sections and also orders processed data to move from the Memory to the Output terminal. The Output terminal of your Odyssey2 computer is the screen of your television set. The Arithmetic Logic Unit is where the computer teaches numbers to tap dance. Its nickname is "number cruncher." It acts on the binary data fed into the computer's memory and registers - and then changes them according to the programmed instructions. Now, you're ready to learn by doing. You're going to enter a program into your computer. Open the fold-out at the front of the book and you'll see what happens to everything along the way. Important point. The neat thing about computers is that they will always follow your instructions with unflagging good faith. The dumb thing about computers is that they will only do what you have instructed them to do. It's very important to make sure that you enter every step and do it right. If you make an error, the computer is going to make an error. Be sure that the power to your Odyssey2 console is turned off. Insert the COMPUTER INTRO cartridge into the console. Be sure the label side is facing the alpha-numeric keyboard. Now, turn on the power. You're going to be talking with your Odyssey2 computer through the keyboard. It will talk back to you over your television screen. [Illustration of the Odyssey2 keyboard] Let's take a brief trip around the keyboard. It has forty-eight keys. Each key has been encoded in the computer languages we're going to be using. You'll find this code on the gatefold at the front of the book. The keyboard also contains some surprises - four games that have been pre-programmed in the cartridge. Press 2 on the alpha-numeric keyboard. A FLASH CARD addition game will appear on your television set. An unsolved addition problem flashes on your screen. You enter the solution through the keyboard. If the answer is less tha 10, preface the number with a 0. (Important! Always use the numeral 0 at the top of the keyboard when entering a 0.) If you give a wrong answer, an angry NO will appear on the screen. If you give a correct answer, it will appear in its proper position. To bring another problem to the screen, summon it from the computer by pressing any key. Adding numbers is no big deal until you see how many addition problems you can solve in one minute. If you keep trying to beat your own record or another player, you can't help but sharpen your skills. Press RESET, then press 3 on the alpha-numeric keyboard and you're into COMPUTER TELEPATHY! It's a high-low game. The computer secretly chooses a number between 00 and 99. The secret number won't appear on the screen - but a question mark will. You make a guess at the correct number and enter it into the computer. Your guess will appear on the screen. It will be followed by an H if it is higher than the computer's secret number - or an L if it is lower. If you guess correctly, the number will be followed by an X. Play against an opponent and see who can guess the computer's secret number in the fewest number of guesses. Now, press RESET, then press 4 on the alpha-numeric keyboard. BETWEEN THE SHEETS appears on the screen. You'll see three sets of numbers. Example: 03 07 00. The first two numbers are the sheets. The computer has thought of another number which it is keeping to itself. The last number is your score. If you think the computers secret number is between 03 and 07 press YES on the alpha-numeric keyboard. If you don't think it falls between 3 and 7, press NO. If you are correct, you score a point and the number will apear between the 3 and 7. If you are wrong, the computer rewards you with a couple of BEEPS right in the ear and your score remains the same. Press RESET, then press 1 and a series of blocks appears on the screen. The blocks flashes in random order and are accompanied by a buzzing sound. We call this spooky effect "THE CREEPY CRAWLER." You can call it anything you want. We can re-program The Creepy Crawler to display other symbols on the screen. There is a large selection of graphics in the memory of your Odyssey2. You'll find the complete collection in the fold-out at the back of the book. The Creepy Crawler program is quite short and represents a good starting point. We're going to follow this and succeeding programs with a sort of road map so you can see where your input goes and what the various parts of the computer do with it. There are two ways you can program your computer. You can speak HEXIDECIMAL code (machine language). An instruction would look like this: 60. Your computer takes 60 and converts it into its binary equivalent: 0110 0000. Notice that this binary translation has eight digits. These are called BITS. Bits are handled by the computer in groups of eight. One group is called a BYTE. A byte is the smallest piece of information a computer can work with. In Odyssey2 Hexidecimal language, 60 means "Load a value into Register 0." (A register is a place where a computer stores information. There are sixteen registers in your Odyssey2. Each register has room for one byte of information.) The second computer language your Odyssey2 understands in called ASSEMBLER. Assembler uses alpha-numeric symbols to input binary code instructions. An instruction in Assembler is more phonetic than Hex - but it is also longer. Example: LDV.0.38 means - Load a value into register 0 - and that value is 38. (Important: Be sure to enter the periods in the assembler instructions or the computer will not know what you're talking about.) In the back of the book, you'll find a complete chart of Instruction Sets for your Odyssey2. INSTRUCTION SETS are the codes that tell your computer what you want it to do with the data you're going to give it. Also Important: "0" is the equivalent of zero in the numeric section of your keyboard. "O" is the letter of the alphabet. Now, open the gatefold at the back of the book. You'll find a flow chart that tells you how to get into the various operating modes of your Odyssey2. These modes are for displaying data in the registers, entering and executing a program, rolling through a program to check data and much more. Leave the front and back gatefolds open. You'll have your reference material right in front of you. We are now ready to re-program the fearsome Creepy Crawler. First, we'll enter in Hex - and then we'll do a variation in Assembler. Creepy Crawler Press the POWER BUTTON OFF and ON to clear the computer. Press RESET "Command" appears on your screen. Your computer is in the COMMAND mode and ready to accept instructions. It knows you want it to do something but doesn't yet know what. Press P "Program" appears on the screen. "Aha," thinks the computer. "Somebody wants to enter a program! I wonder what language this person will speak!" Press M "Hex Input" appears on the screen. The computer now knows you will be communicating in HEX. You're going to be using the Hexidecimal Operational Code (OP CODE). Press I Step 00 appears on the screen and the computer is ready and waiting to accept data. 00 Press 60 This is Op code for Load Register 0. Register 0 is one of sixteen registers in your Odyssey2 that make up part of its Random Access Memory (RAM). Each register is a small memory divide that provides temporary storage for data and instructions which will eventually be needed by the ARITHMETIC LOGIC UNIT (ALU) - the place where all simple reasoning and arithmetic operations are performed. Look at the registers in the computer as sixteen in and out boxes on a desk that is shared by both you and the Arithmetic Logic Unit. Press ENTER Program Step 01 appears on the screen. Register 0 has now been activated to accept your entry upon execution of the program. (The program steps you enter into the computer do not actually become functional until you press E [EXECUTE] at the completion of the program.) 01 Press 3A You have just selected an electronic figure from your computer's gallery of electronic art and symbols, which are stored in the symbol/sound generator. You'll find the entire gallery in the fold-out at the back of the book. We've selected the little man as an example, but you can actually use any of the figures or symbols for this program. They have been permanently stored in your computer. There are two parts to the memory unit in your computer. The ROM (Read Only Memory) contains the instruction sets and constants to be used in programming. (The constants may be repetitive numbers needed for mathematical computation by the ALU - Arithmetic Logic Unit, or they may be letters, numbers, or symbols which you have entered into the Odyssey21 in a program which will remain the same throughout the program. See the program "Message.") The other part of the computer's memory is called RAM (RANDOM ACCESS MEMORY). This memory component is like a blackboard. Programs, instruction sets and constants can be entered and later erased so that new data can be entered. You're writing this program on the RAM component of the microprocessor in your Odyssey2. Press ENTER Program step 02 appears on the screen. The little man will be loaded into Register 0. 02 Press 61 This is Op Code for LOAD REGISTER 1. It tells your computer you want to give input to that data storage unit. Press ENTER Program step 03 appears on the screen - and the door to Register 1 will open to receive data 03 Press 0C This is Op Code for a blank like the space between words in a sentence. Press ENTER Program step 04 appears on your screen. The blank will be loaded in to Register 1. 04 Press 6B This is Op Code for positioning. You are opening the door to Register B and telling it you want it to display the little man at a certain place on the screen upon execution of the program. You'll let it know where. Press ENTER Program step 05 appears. The door to Register B will open. 05 Press 00 This entry tells the computer you will want it to display the little man at the furthest left position on the screen. Press ENTER Program step 06 appears on your screen. The positioning information will be loaded into Register B. Register B is the register that positions symbols or characters on the screen. It has been given eleven positions. 00 is the furthest left. 0A is the furthest right. When Register B outputs on the screen, it automatically increments or advances by one. If we output a symbol in 00 (position one), the symbol will appear in the first position and Register B will then advance automatically to position 2 (01). If Register B outputs in the last position (0A), it automatically resets itself back to the first position (00) on the next step. Whatever data was in that first position will be replaced by the new input. 06 Press C0 This is the Op Code that tells the computer you are going to want to bring that little man to the screen. You have given him a way to get out of Register B. Press ENTER Program Step 07 appears on the screen. 07 Press C1 This is Op Code for telling the computer you want to bring that blank in Register 1 to the screen. Press ENTER Program step 08 appears on your screen to tell you everything is going along smoothly. 08 Press 05 It's sound effects time. This is an Op Code that tells the computer you will want to hear a one second buzz. Press ENTER Program step 09 appears. 09 Press 08 This Op Code tells the computer you want it to come with an unlimited sequence of random numbers. The computers that encipher and decipher secret messages for governments do this everyday. In the old days, crypt keys remained constant and could be broken easily. Today, they change constantly and at random. Today, it takes one computer to break another's cipher. Press ENTER The random number instructions are entered into your computer. Program step 10 appears on the screen. 10 Press BB This is Op Code for UNPACK Register B. This is the Register we use to position our little man on the screen. This unpacking instruction takes the random two digit number selected by the Accumulator and places one digit in Register B (we are unpacking Register B, thus the Op Code BB) and the other digit in the Register immediately following B, which is Register C. The digit in Register C is ignored. Another example of unpacking - If we had unpacked Register 0, the Op Code would have been B0, and one digit on the random number would have been placed in Register 0 and the second digit in Register 1. To look at it another way, think of the Accumulator as a suitcase and the registers as a tall dresser with 16 drawers. You unpack two items from your suitcase and put the first away in a drawer. The second item will automatically go to the drawer just below it. At the end of the Creepy Crawler program, a variation is written explaining how to use the second digit of the random number which was loaded into Register C, along with numerous figures to execute a random display of figures on the screen. Through this unpacking instruction, the positioning Register (Register B) is loaded from the Accumulator with a random number. It is this instruction which will cause our little man to travel to unpredictable places on the screen. (The Accumulator is a small memory device in the CPU that provides temporary storage for the Arithmetic Logic Unit. It can store the result of an ALU operation or serve as an operation source [OPERAND] for the ALU.) Press ENTER The unpacking instruction is entered and programm step 11 appears on your screen. 11 Press 12 This OP Code tells your computer you're going to want it to return to a previously programmed step. Press ENTER Program step 12 appears on the screen and the computer wonders which program steps you wish repeated. 12 Press 06 You have just told the computer you want it ot go through the motions and always return to program step 06. This was the place you wanted the little man positioned on the screen which was subsequently combined with a random number to change the positioning on the screen. In effect, you have now "looped" part of your program. It will do its thing endlessly with endless variations. Press ENTER The computer salutes and will do as you ordered. Program step 13 appears. Press RESET The program is stored and you are back in the COMMAND mode. "Command" appears on your screen. Press E You have instructed the computer to execute your instructions. The fearsome Creepy Crawler appears on your screen. The little man or whatever symbol you have chosen will flash and buzz in different positions on the screen. Forever. Or, until you turn it off. Or, change the program. Whichever comes first. Important! The power switch on your console is your program eraser. Turn it off and the program is cleared from the unit automatically. Turn it on - and you're ready to enter a new program. Now that you've entered Creepy Crawler in HEX, Try entering this variation in ASSEMBLER language. We will call this program Creepy Crawler with an All-Star Cast of Thousands. First, turn the power off and on to erase any previous programming. Now, check the fold-out Operational Flow Chart to see how to get into the Assembler Input Mode. Press RESET Press P Press A Press I You are now in the Assembler Mode at program step 00 and ready to go. One thing. Be sure to enter the periods as well as the letters and numbers. Press L Press D Press V Press . Press 2 Press . Press 1 Press 3 Press enter We are now at Program step 02. Continue entering in Assembler until you get to Program step 13. At this step you will begin entering a variety of symbols in HEX. There is no Assembler equivalent for them - so after Program step 12, switch over to the HEX Input Mode. Check the Operational Flow Chart and then - Press CLEAR Press ROLL Press CLEAR Press M Press I After you finish entering the program, press RESET to store the program - then press E (EXECUTE) and watch what happens! Creepy Crawler Version II Hex Assembler Step Code Code Byte Remarks ------------------------------------------------------------------------ 00 62 13 LDV.2.13 2 Load Reg. 2 with 13 02 08 RND 1 Accum. selects a random number 03 BB UNP.B 1 Unpack the random number into Reg. B and C 04 9C LDA.C 1 Load the Accum. from Reg. C 05 E2 ADD.2 1 Add the contents of Reg. 2 to the Accum. 06 AC STO.C 1 Store the contents of the Accum. in Reg. C 07 09 MOV 1 Load Accum. from a Program step 08 0B OTA 1 Output from Accum. to screen 09 05 SIG 1 One second buzz 10 00 NOP 1 No operation (used as pause) 11 12 02 GTO.02 2 Instructs Odyssey2 to go to Program step 02 and repeat program 13 32 1 Must enter Hex Mode (see page 27) 14 33 1 15 3A 1 16 34 1 17 35 1 Hex codes for various symbols. These 18 37 1 symbols with their Hex Code equivalents 19 3D 1 are shown at the front of the book. 20 3E 1 21 36 1 22 3C 1 The Roll Mode - Your Program Trouble Shooter The Roll Mode is for checking a program step to be sure it contains the correct data. It is also for making a change in a program step without having to erase and re-enter an entire program. To enter the Roll Mode, press R if you are in either the Assember or HEX input modes. If you are in the EXECUTION mode, press RESET, the P, the M (HEX) or A (ASSEMBLER) - and then press R. Then, press U to display the program steps upward (00-99) - or press D to display the program steps downward (99-00). The Roll Mode will always display its information in HEX - even if you have been entering in Assembler. If everything checks out, roll to the last program step entered and press CLEAR to re-enter the Assembler or HEX input mode. If you wish to make a change, press CLEAR at the program step you wish to change. The data will be cleared. Enter M for HEX or A for Assembler, depending on the code you have been using. Press I - the program step number you wish to change will appear on the screen. Enter the new data. Press RESET You will be back in the COMMAND Mode and are ready to go on with the program. The following series of programs will be presented with a running commentary that will tell you exactly where the data is going and what is happening to it. These programs are written in HEX code. At the end of each program, you'll find a summary written in HEX as well as Assembler, so you can enter each program in either language. Addition - Program A This program will add two one digit numbers and display the total. Press the POWER BUTTON off and on to clear the computer. Press RESET "Command" appears on your screen. Your computer is ready to accept instruction. Press P "Program" appears on the screen. Press M "Hex Input" appears on the screen. You have told the computer you will be using the Hexidecimal Operational Code (Op Code). Press I Step 00 appears on the screen. The computer is ready to accept data. 00 Press 70 Press ENTER You have told the computer you are going to input the first number into Register 0. 01 Press 04 Press ENTER You instruct the computer to feed the second number of the addition problems in to the Accumulator. Remember, the Accumulator provides temporary storage for the ALU where the numbers are going to be crunched. 02 Press E0 Press ENTER This instructs the computer to add the contents of Register 0 to the contents of the Accumulator and to store the sum in the Accumulator. 03 Press B1 Press ENTER This Op Code is an unpacking instruction. It tells the computer to unpack the sum which has been stored in the Accumulator into Register 1 and Register 2. 04 Press 6B Press ENTER This starts a positioning instruction. 05 Press 00 Press ENTER This Op Code tells the computer to display subsequent information at the 00 position on your TV screen. 06 Press C1 Press ENTER You tell the computer you will want to output the information in Register 1 (first digit sum). 07 Press C2 Press ENTER You also want to output the data in Register 2 (Second digit sum). 08 Press 12 Press ENTER This tells the computer you want it always to return to a certain step and repeat the program from that point. 09 Press 00 Press ENTER 00 is the step you want the computer to return to and repeat. Now, the computer will perform a continuous series of addition problems. The program is now completed. Press RESET The program is now stored in the computer's memory and you are back in the COMMAND Mode. Press E The computer executes your program. A question mark appears on the screen. The computer is asking for two 1 digit numbers to add. Enter the First Number. Press any digit from 0 through 9. You will hear a beep confirming entry. The number will not appear on the screen. That instruction was not included in this program. Enter the Second Number. Press any digit 0 through 9 and the sum total of the two entered numbers will immediately appear on the screen. To enter a new problem, press any single digit number. Then, press the other single digit number. The previous sum will be replaced by the answer of the new addition problem as soon as you have entered the second number of the new problem. Now, here is the addition problem you have just entered expressed in both HEX and ASSEMBLER codes. Note the following points. Important: Remember to get into the proper input mode for the language you are using. Press PMI for HEX. Press PAI for Assembler. Very Important: Look at Program step 04. It is a two Byte instruction. Remember, in Binary each byte is composed of eight bits. 6B (HEX = 0110 1011 (BINARY). 00 (HEX) = 0000 0000 (BINARY). Therefore, 6B 00 is a two byte instruction. If you are in the HEX mode, each Byte must be entered separately. Press 6B Press ENTER Press 00 Press ENTER If you are in the Assembler mode, both Bytes are fed into the computer with one entry. Press L Press D Press V Press . Press B Press . Press 0 Press 0 Press ENTER In either language, you will see Program step 06 on the screen after the data is entered. Now, push the Power Button to erase any previous data...choose one of the input codes...and enter the program. Be sure to press ENTER after each step. Addition - Program A Hex Assembler Step Code Code Byte Remarks ------------------------------------------------------------------ 00 70 INP.0 1 Input Reg. 0 with 1st number 01 04 INA 1 Input Accum. with 2nd number 02 E0 ADD.0 1 Add Reg. 0 to Accum. 03 B1 UNP.1 1 Unpack Accum. into REg. 1 and Reg. 2 04 6B 00 LDV.B.00 2 Set output position to 00 06 C1 OUT.1 1 Output Reg. 1, 1st digit sum 07 C2 OUT.2 1 Output Reg. 2, 2nd digit sum 08 12 00 GTO.00 2 Go to step 00 and repeat Addition - Program B This program will also add two one digit number. However, this time when you enter the second number, the entire problem will appear on the screen. (Example: 2+4=6). You will be entering + and = signes in this program. First, press the POWER BUTTON off and on to clear the computer. Then - Press RESET "Command" will appear on your screen, and your computer is all ears. Press P "Program" appears on your screen. Press M "Hex Input" appears on your screen. The computer knows you will be using Op COde (Hexidecimal Operation Code). Press I Step 00 appears on the screen. You are ready to input data. 00 Press 70 Press ENTER You tell the computer the first number will be entered into Register 0. 01 appears on your screen. 01 Press 04 Press ENTER You tell the computer to accept the second number into the Accumulator. 02 appears on the screen. 02 Press 6B Press ENTER This starts an output position entry. 03 Press 00 Press ENTER The output position is set at 00 at the far left of the screen. 04 Press C0 Press ENTER The output channel from Register 0 will open for the first number of the addition problem. 05 Press 63 Press ENTER The input channel to Register 3 will open. 06 Press 10 Press ENTER 10 will be loaded into Register 3. 10 is Op Code for the (+) sign. 07 Press C3 Press ENTER The output channel from Register 3 will open so the (+) sign can be displayed on the screen. 08 Press 0B Press ENTER The output channel of the Accumulator will open so that the second number can be displayed on the screen. 09 Press 63 Press ENTER The input channel to Register 3 will open. 10 Press 2B Press ENTER 2B will be loaded into Register 3. 2B is Op Code for the (=) sign. 11 Press C3 Press ENTER The output channel from Register 3 is opened so the (=) sign may be displayed on the screen. 12 Press E0 Press ENTER This instruction adds the contents of Register 0 to the contents of the Accumulator and stores the result in the Accumulator. Remember, Register 0 contained the first number of the addition problem. The Accumulator held the second number. 13 Press B1 Press ENTER This program step unpacks the contents of the Accumulator storing the first digit of the sum in Register 1 and the second digit of the sum in Register 2. 14 Press C1 Press ENTER The output channel from Register 1 will open to let the first digit sum be displayed on the screen. 15 Press C2 Press ENTER The output channel from Register 2 will open to let the second digit sum be displayed on the screen. 16 Press 12 Press ENTER This begins an instruction to return to a previous step. 17 Press 00 Press ENTER The computer is instructed to return to step 00 and be ready to solve a new addition problem. The old problemm will not erase from the screen until both digits of the new problem are entered. Press RESET The program is now stored in the computer. Press E The computer is ready to execute the program. A question mark appears on the screen asking for input. Press any single digit number. Nothing appears on the screen. Press a second single digit number. The entire problem and the solution appear on the screen. Both will remain there until two new digits are entered. Addition - Program B Hex Assembler Step Code Code Byte Remarks ------------------------------------------------------------------ 00 70 INP.0 1 Input Reg. 0 with 1st number 01 04 INA 1 Input Accum. with 2nd number 02 6B 00 LDV.B.00 2 Set output position 04 C0 OUT.0 1 Output 1st number from Reg. 0 05 63 10 LDV.3.10 2 Load Reg. 3 with (+) sign 07 C3 OUT.3 1 Out Reg. 3, (/) + on screen 08 0B OTA 1 Output 2nd number 09 63 2B LDV.3.2B 2 Load Reg. 3 with (=) sign 11 C3 OUT.3 1 Output Reg. 3, (/) = on screen 12 E0 ADD.0 1 Add Reg. 0 to Accum. 13 B1 UNP.1 1 Unpack Accum. into Reg. 1 and Reg. 2 14 C1 OUT.1 1 Output Reg. 1, 1st digit sum 15 C2 OUT.2 1 Output Reg. 2, 2nd digit sum 16 12 00 GTO.00 2 Go to step 00 and repeat Addition - Program C After you enter this program a question mark on the screen asks you to press in two one digit numbers for the computer to add. The first number appears on the screen followed by (+) sign. When you press the second number, it appears on the screen followed by a (=) sign and the answer. When the first digit of the next addition problem is entered, the first problem will disappear from the screen. To begin, turn off the power to erase the previous program. Press RESET You[sic] computer is in the "Command" Mode and ready to accept instructions. Press P The computer enters the "Program" Mode. Press M "Hex Input" appears on the screen. The computer is ready to accept instructions in Op Code. Press I Step 00 appears on the screen and the computer is ready for the program. 00 Press 6B Press ENTER You are setting the output position of Register B. 01 Press 00 Press ENTER That output position is 00 at the far left of the screen. 02 Press 70 Press ENTER You tell the computer that the first number of the addition problem will be stored in Register 0. 03 Press C0 Press ENTER This tells the computer you will want it to output the contents of Register 0. 04 Press 63 Press ENTER You are preparing Register 3 to accept data. 05 Press 10 Press ENTER Register 3 will be loaded with a 10 - the code for a (+) sign. You will find the complete code for all of the graphics stored in your computer on the fold-out at the back of the book. 06 Press C3 Press ENTER This will open the way to output the (+) sign from Register 3. 07 Press 04 Press ENTER This will open the Accumulator for future input. 08 Press 0B Press ENTER The output channel of the Accumulator is set to open. 09 Press 63 Press ENTER You want to laod a value into Register 3. 10 Press 2B Press ENTER That value is 2B - the code for the (=) sign. 11 Press C3 Press ENTER This will open the way to output the (=) sign from Register 3. 12 Press E0 Press ENTER The computer will then add the contents of Register 0 to the Accumulator. Register 0 has already been instructed to accept the first number in the addition problem (Step 02) - and the Accumulator has been instructetd to accept the second number. 13 Press B1 Press ENTER This Op Code will unpack the contents of the Accumulator (which contains the sum) into Register 1 and Register 2. 14 Press C1 Press ENTER This will open the output channel of Register 1. 15 Press C2 Press ENTER This will open the output channel of Register 2. 16 Press 70 Press ENTER This input is a pause operation. It tells the computer to leave the first problem on the screen until another problem is entered. 17 Press 6C Press ENTER Register C will be opened for loading. 18 Press 0B Press ENTER Register C will be loaded with 0B - the Op Code for the decimal number 11, which is exactly the number of positions available on the screen. 19 Press 67 Press ENTER Register 7 will be ready for loading. 20 Press 0C Press ENTER 0C is Op Code for blank spaces as indicated in the computer graphics section in the fold-out at the back of the book. Register 7 will be loaded with blank spaces. The computer will use these blank spaces to erase the old problem on the screen when the first digit of the new problem is entered. 21 Press 9C Press ENTER The Accumulator will be loaded with the contents of Register C - the decimal number 11. 22 Press 64 Press ENTER This will open Register 4 to accept data. 23 Press 00 Press ENTER Register 4 will be loaded with 00. 24 Press 02 Press ENTER The amount in the Accumulator (11 - the number of positions on the screen) will be decremented (subtracted) by one each time this step is reached. 25 Press C7 Press ENTER Register 1 will output its blank spaces. 26 Press 24 Press ENTER This is a branch instruction - sort of a fork in the electronic road. The computer is instructed to continue on to the next program step if the number in the Accumulator equals the number in Register 4 (00). 27 Press 24 Press ENTER The computer is instructted to return to step 24 if the number in Register 4 is not equal to the Accumulator. Step 24 will decrement the contents of the Accumulator (which originally was 11) by 1 each time until the Accumulator is reset at 00 to match Register 4. Program steps 16 through 27 demonstrate how a computer erases by outputting blank spaces to the screen. 28 Press 6B Press ENTER We are resetting Register B to return to its original output position once the Accumulator is equal to Register 4. 29 Press 00 Press ENTER The output position of Register B is set at the extreme left position of the screen. 30 Press 12 Press ENTER This Op Code instructs the computer to branch to another program step when the amount in the Accumulator equals 00. 31 Press 03 Press ENTER The step the cocmputer returns to is 03. Now, you are able to enter and solve repeated addition problems. Press RESET The program is stored. Press E The program is executed. See the beginning of the program for use instructions. Addition - Program C Hex Assembler Step Code Code Byte Remarks ---------------------------------------------------------------- 00 6B 00 LDV.B.00 2 Set output position to 00 02 70 INP.0 1 Input 1st number to Reg. 0 03 C0 OUT.0 1 Output Reg. 0 04 63 10 LDV.3.10 2 Load Reg. with (+) sign 06 C3 OUT.3 1 Output (+) sign from Reg. 3 07 04 INA 1 Input to Accum. (second number) 08 0B OTA 1 Output from Accum. 09 63 2B LDV.3.2B 2 Load Reg. 3 with (=) sign 11 C3 OUT.3 1 Output (=) sign from Reg. 3 12 E0 ADD.0 1 Add Reg. 0 to Accum. 13 B1 UNP.1 1 Unpack Accum. to Reg. 1 and Reg. 2 14 C1 OUT.1 1 Output Reg. 1 15 C2 OUT.2 1 Output Reg. 2 16 70 INP.0 1 This is used as a pause operation 17 6C 0B LDV.C.0B 2 Load Reg. C with Hex 0B (#11) 19 6C 0C LDV.7.0C 2 Load Reg. 7 with blank spaces 21 9C LDA.C 1 Load Accum. from Reg. C 22 64 00 LDV.4.00 2 Load Reg. 4 with 00 24 02 DEC 1 Subtract 1 from Accum. 25 C7 OUT.7 1 Output Reg. 7 (blank spaces) 26 24 24 BNE.4.24 2 Branch if Accum. does not = Reg. 4 28 6B 00 LDV.B.00 2 Set output position to 00 30 12 03 GTO.03 2 Go to step 03 and repeat One Digit Multiplication After you enter this program, a question mark will appear on the screen asking for input. The first digit entered is the number you wish to multiply (the nultiplicand). It appears on the screen with an (X) sign. The second digit entered is the multiplier. The complete problem will now appear on the screen along with the answer. Odyssey2 solves multiplication through an addition process. If the problem is 3 X 7, the computer will arrive at the answer by adding 7+7+7. Program steps 00 through 11 are instructions which allow the problem to be displayed on the screen. The mathematical operational sequence begins with step 12. First, press the POWER BUTTON off and on to erase the previous program. Press RESET You are in the "Command" Mode. Press P You enter the "Program" Mode. Press M "Hex Input" appears on the screen. The computer is ready for Op Code instructions. Press I Step 00 appears on the screen and the computer is ready for the program. 00 Press 6B Press ENTER The output position of Register B is ready for setting. 01 Press 00 Press ENTER You set the output of Register B for the far left of the screen. 02 Press 70 Press ENTER The multiplicand is directed to be stored in Register 0. 03 Press C0 Press ENTER Register 0 is given an output channel. 04 Press 66 Press ENTER The door will be opened to Register 6. 05 Press 29 Press ENTER An (X) sign will be entered into Register 6. 06 Press C6 Press ENTER Register 6 is given an output channel. 07 Press 71 Press ENTER The multiplier will be stored into Register 1. 08 Press C1 Press ENTER The multiplier is given a way out of Register 1. 09 Press 67 Press ENTER The door to Register 7 is instructed to open. 10 Press 2B Press ENTER 2B is Op Code for (=). The (=) sign will be loaded into Register 7. 11 Press C7 Press ENTER This will provide an output channel for Register 7. 12 Press 90 Press ENTER The Accumulator is instructed to be ready to accept data from Register 0. This is the Register that holds the number you want to multiply. The Accumulator will be loaded with the same value as the contents of Register 0 - however, Register 0 will continue to retain its data. 13 Press E0 Press ENTER The computer is instructed to add the contents of the Accumulator to Register 0. Remember, that Odyssey2 multiplies by a series of addition steps. This is the first addition step. 14 Press A2 Press ENTER The sum of the digits from the Accumulator and Register 0 will be stored in Register 2. 15 Press 91 Press ENTER The Accumulator will be loaded from Register 1 which holds the multiplier. The Accumulator will now know the number of addition steps it must perform to arrive at an answer. 16 Press 02 Press ENTER This step will decrement the Accumulator which contains the multiplier by 1 so that the computer can keep track of how many addition steps have been made. 17 Press A1 Press ENTER The difference will be stored in Register 1. 18 Press 63 Press ENTER The door to Register 3 will open. 19 Press 01 Press ENTER 01 will be stored in Register 3. This will give the computer a reference point which will halt the addition process. When the Accumulator contains the contents of Register 1 (the multiplier), it is compared to the contents of Register 3 (which is 01). If the contents in Register 1, which is now in the Accumulator, and Register 3 coincide, the computer will stop adding. If they are not equal, the computer will loop back and continue the addition process. 20 Press 33 Press ENTER This starts a branch operation. 21 Press 25 Press ENTER The computer is instructed to branch to step 25 if the contents of the Accumulator and Register 3 are equal. In which case, the answer will be unpacked and displayed on the screen. 22 Press 92 Press ENTER The Accumulator will be loaded with the information in Register 2, which contains the data fed in Program Step 14. 23 Press 12 Press ENTER The computer is instructed to return to a previous step in the program if the conditions in program step 19 have not been met. 24 Press 13 Press ENTER The computer is instructed to return to step 13 and once aggain add the contents of Register 0 to the Accumulator. (Register 0 holds the multiplicand.) 25 Press 92 Press ENTER The Accumulator will be loaded with the contents of Register 2 which contains the sum of the addition operations. We are almost at the end of the tunnel. This operation is performed when the contents of the Accumulator and Register 3 are equal. 26 Press B4 Press ENTER This is a two digit unpacking operation, which has been explained in Addition Program A. 27 Press C4 Press ENTER An output channel for Register 4. 28 Press C5 Press ENTER An output channel for Register 5. 29 Press 12 Press ENTER You instruct the computer to return to a previous program step. 30 Press 00 Press ENTER That step is 00. The computer will now be ready to accept a new multiplication problem. Press RESET The program is stored. Press E The program is executed. One Digit Multiplication Hex Assembler Step Code Code Byte Remarks -------------------------------------------------------------- 00 6B 00 LDV.B.00 2 Set output position 02 70 INP.0 1 Multiplicand stored in Reg. 0 03 C0 OUT.0 1 Output multiplicand 04 66 29 LDV.6.29 2 Symbol (X) stored in Reg. 6 06 C6 OUT.6 1 Output Reg. 6; Reg.6=(X) 07 71 INP.1 1 Multiplier stored in Reg. 1 08 C1 OUT.1 1 Output Multiplier 09 67 2B LDV.7.2B 2 Symbol (=) stored in Reg. 7 11 C7 OUT.7 1 Output Reg. 7 12 90 LDA.0 1 Load Accum. from Reg. 0 13 E0 ADD.0 1 Add Accum. to Reg. 0 14 A2 STO.2 1 Store sum in Reg. 2 15 91 LDA.1 1 Load Accum. from Reg. 1 16 02 DEC 1 Decrement Accum. by 1 17 A1 STO.1 1 Store difference in Reg. 1 18 63 01 LDV.3.01 2 Load Reg. 3 with 01 20 33 25 BEQ.3.25 2 Go to step 25 if Accum. = Reg. 3 22 92 LDA.2 1 Load Accum. from Reg. 2 23 12 13 GTO.13 2 Go to step 13 25 92 LDA.2 1 Load Accum. from Reg. 2 26 B4 UNP.4 1 Unpack two digits 27 C4 OUT.4 1 Output Reg. 4 28 C5 OUT.5 1 Output Reg. 5 29 12 00 GTO.00 2 Go to step 00 and repeat One Digit Division A question mark will appear on the screen. The first number entered will be the dividend and it will be followed by a (./.) sign. The second number entered will be the divisor. It will appear on the screen along with an (=) sign and the answer. Your Odyssey2 computer accomplishes division by a series of subtractions. It's the Odyssey2 multiplication process in reverse. Note: There are two conditions in division that must be provided. The first condition is when the divisor can be divided into the dividend equally. Example: 6/2 = 3. The second condition is when the divisor cannot be divided into the dividend equally and there is a remainder. Example: 9/2=4+R. Your Odyssey2 has been instructed to display (+R) if there is a remainder. This program provides branching instructions to satisfy both conditions. To begin, turn the POWER BUTTON off and on to erase any previous program. Press RESET You are in the "Command" mode. Press P You have entered the "Program" mode. Press M "Hex Input" appears on the screen. The computer is ready to accept instructions in Op Code. Press I Step 00 appears on the screen, and you are ready to enter the program. 00 Press 63 Press ENTER The door to Register 3 will be opened. 01 Press 00 Press ENTER We call this "initialization" - a step to insure that Register 3 is set at absolute zero value after each problem is solved. Register 3 will contain the sum of the subtraction operations Odyssey2 will perform to find the quotient. 02 Press 6B Press ENTER The door to Register B will be opened. 03 Press 00 Press ENTER Register B will be positioned to output at the far left of the screen. 04 Press 70 Press ENTER The number to be divided (the dividend) will go into Register 0 the dividend must always be larger than the divisor. 05 Press C0 Press ENTER The output channel to Register 0 is set to open. 06 Press 69 Press ENTER Register 9 will be opened for input. 07 Press 2A Press ENTER 2A is Op Code for (./.). The division sign will go into Register 9. 08 Press C9 Press ENTER The output channel of Register 9 is set to open. 09 Press 71 Press ENTER The divisor will be loaded into Register 1. 10 Press C1 Press ENTER The output channel of Register 1 is instructed to open. 11 Press 6A Press ENTER The door to Register A will be opened. 12 Press 2B Press ENTER 2B is Op Code for (=). The equal sign will go into Register A. 13 Press CA Press ENTER The Register A output channel is instructed to open. 14 Press 91 Press ENTER The Accumulator will be loaded with the contents of Register 1 which contains the divisor. We are going to use a sample problem so the explanation will be easier (6/2=3). The Accumulator will be loaded with the divisor (2). 15 Press D0 Press ENTER The contents of the Accumulator will be subtracted from the contents of Register 0 which contains the dividend (6). 16 Press A0 Press ENTER The difference (4) between the dividend and the divisor (6-2=4) will be stored in Register 0. 17 Press 93 Press ENTER The Accumulator will be loaded with the contents of Register 3. This is the Register that was "initialized" at 00 so that we could keep track of the number of times we subtracted. 18 Press 03 Press ENTER A 1 will then be added to the Accumulator. This is called an increment. 19 Press A3 Press ENTER The sum of the Accumulator is then stored in Register 3. This Register now contains 01. 20 Press 90 Press ENTER The Accumulator will be loaded with the contents of Register 0. Register 0 has been loaded with a value of 4, the difference between the dividend and the divisor. The value was loaded into Register 0 in Program step 16. 21 Press 13 Press ENTER This will be the start of a branch operation. 22 Press 40 Press ENTER The computer wil branch to step 40 if the Accumulator equals 0. Once the Accumulator equals 0, the problem is finished and Program step 40 will unpack the answer and it will be displayed on the screen. 23 Press 91 Press ENTER If the Accumulator does not equal 0, it will go to this program step. The Accumulator will be loaded with the contents of Register 1 which contains the divisor (2). 24 Press 50 Press ENTER Another branch operation will be started. 25 Press 28 Press ENTER The computer will be instructed to branch to program step 28 if Register 0 which contains the dividend (4) is less than the Accumulator which contains the divisor (2) from Register 1. 26 Press 12 Press ENTER This tells the computer to return to a previous step if Register 0 is not less than the Accumulator. 27 Press 15 Press ENTER This completes the return instructions. The computer is programmed to return to step 15. This step begins the subtraction operations which will continue until Register 0 is loaded into the Accumulator at step 21 and, the Accumulator equals 0 in this example. When this condition is met, Odyssey2 will loop to Program step 40. 28 Press 93 Press ENTER This is the step your computer will branch to if a remainder is included. The branching instructions were given in steps 24 and 25. They programmed the computer to branch to step 28 if Register 0 which contains the dividend is less than the Accumulator which at this point, contains the divisor. We will use 9/2=4+R as our sample problem. All programsteps have been the same up to this point. The computer has looped to step 15 several times. Register 0 now contains 01 and the Accumulator contains 02. This step will load the Accumulator from Register 3 which contains the number of times (2) has been subtracted from (9) which is (4). 29 Press B4 Press ENTER This instruction will unpack the answer. 30 Press C4 Press ENTER The first digit, stored in Register 4, will be displayed on the screen. 31 Press C5 Press ENTER The second digit, stored in Register 5, will be displayed on the screen. 32 Press 66 Press ENTER Register 6 will open. 33 Press 10 Press ENTER 10 will be loaded into Register 6. 10 is the Op Code for (./.). 34 Press 67 Press ENTER Register 7 will be opened. 35 Press 13 Press ENTER 13 will be loaded into Register 7. 13 is the Op Code for (R). 36 Press C6 Press ENTER The output channel for the (./.) sign will be opened. 37 Press C7 Press ENTER The output channel for (R) will open. 38 Press 12 Press ENTER The computer is instructed to return to a previous step. 39 Press 00 Press ENTER The computer will return to step 00 and be ready to solve a new problem. Our program ends at this point if we have solved a problem that contains a remainder. If not, as in our first example (6/2=3), we would have jumped from Program step 21 to Program step 40. 40 Press 93 Press ENTER The Accumulator will be loaded with the contents of Register 3. It will contain the number of times the divisor has been subtracted from the dividend. In step 21 the computer was programmed to branch to this step when the contents of the Accumulator equaled 0. We were using 6/2 as our example so at this point Register 3 contains (3) ---the number of times (2) has been subtracted from (6). 41 Press B4 Press ENTER This unpacking operation will convert the answer from binary into decimal. 42 Press C4 Press ENTER The output channel of Register 4 will be opened for the first digit. 43 Press C5 Press ENTER The output channel of Register 5 will be opened for the second digit. 44 Press 66 Press ENTER Register 6 will open. 45 Press 0C Press ENTER Register 6 will be loaded with 0C which is Op Code for a blank space. 46 Press 67 Press ENTER Register 7 will open. 47 Press 0C Press ENTER Register 7 will be loaded with a blank space. Registers 6 and 7 have been loaded with blanks so that (+R) will not be displayed on the screen when this branch of the program is employed by the computer. 48 Press C6 Press ENTER The output channel from Register 6 will open. 49 Press C7 Press ENTER The output channel from Register 7 will open. 50 Press 12 Press ENTER The computer is instructed to return to a previous step. 51 Press 00 Press ENTER The computer is instructed to return to step 00 and be ready to solve another problem. Press RESET The program is stored. Press E The program is executed. One Digit Division Hex Assembler Step Code Code Byte Remarks ----------------------------------------------------------------------------- 00 63 00 LDV.3.00 2 Reg. 3 = 00 (initialization) 02 6B 00 LDV.B.00 2 Reg. B = 00 (positioning) 04 70 INP.0 1 Dividend stored in Reg. 0 05 C0 OUT.0 1 Output Reg. 0 06 69 2A LDV.9.2A 2 Symbol (./.) stored in Reg. 9 08 C9 OUT.9 1 Output Reg. 9 09 71 INP.1 1 Divisor stored in Reg. 1 10 C1 OUT.1 1 Output Reg. 1 11 6A 2B LDV.A.2B 2 Symbol (=) stored in Reg. A 13 CA OUT.A 1 Output Reg. A 14 91 LDA.1 1 Load Accum. from Reg. 1 15 D0 SUB.0 1 Sub Accum. from Reg. 0 16 A0 STO.0 1 Store difference in Reg. 0 17 93 LDA.3 1 Load Accum. from Reg. 3 18 03 INC 1 Add 1 to the Accum. 19 A3 STO.3 1 Store sum in Reg. 3 20 90 LDA.0 1 Load Accum. from Reg. 0 21 13 40 BRZ.40 2 Branch to step 40 if Accum. equals 0 23 91 LDA.1 1 Load Accum. from Reg. 1 24 50 28 BLS.0.28 2 Branch to step 28 if Reg. 0 is less than Accum. 26 12 15 GTO.15 2 Go to step 15 28 93 LDA.3 1 Load Accum. from Reg. 3 29 B4 UNP.4 1 Unpack two digits 30 C4 OUT.4 1 Output 1st digit which is stored in Reg. 4 31 C5 OUT.5 1 Output 2nd digit which is stored in Reg. 5 32 66 10 LDV.6.10 2 Symbol (+) stored in Reg. 6 34 67 13 LDV.7.13 2 Symbol (R) stored in Reg. 7 36 C6 OUT.6 1 Output (+) sign 37 C7 OUT.7 1 Output (R) 38 12 00 GTO.00 2 Go to step 00 40 93 LDA.3 1 Load Accum. from Reg. 3 41 B4 UNP.4 1 Unpack two digits 42 C4 OUT.4 1 Output 1st digit from Reg. 4 43 C5 OUT.5 1 Output 2nd digit from Reg. 5 44 66 0C LDV.6.0C 2 A blank is stored in Reg. 6 46 67 0C LDV.7.0C 2 A blank is stored in Reg. 7 48 C6 OUT.6 1 Output blank 49 C7 OUT.7 1 Output blank 50 12 00 GTO.00 2 Branch to step 00 Area Problems Using "Go to Subroutine" and "Return" This program gives you an example of how and when to use the instructions "Go to Subroutine" and "Return". A "Go to Subroutine" instruction tells the computer to branch to a specific program step which contains an operation you may wish to use several times in one program. You can use the same operation several times without having to rewrite it. When writing a prgram using this instruction, the next program step after the "Go to Subroutine" instruction must be reserved for returning from the Subroutine. A program having a "Go to Subroutine" instruction must have a "Return from Subroutine" instruction as well. After you enter this program, you will be able to find the area of a rectangle or the area of a triange. First, enter the base measurement - then, enter the height measurement. Press 1 to find the area of a rectangle. (Base * Height = Area). Press 2 to find the area of a triangle. (Base * Height / 2 = Area). Before entering this program, refer to the program on pages 69 and 70 while we explain how it works. Program steps 00 through 08 will be the same for both problems. (00 through 08) Step 08 programs your selection of 1) rectangle area problem, or 2) triangle area problem to be loaded into the Accumulator. First, we'll see what happens when 1 is loaded into the Accumulator. (09 and 10) Steps 09 and 10 instruct the computer to branch to Program step 13 if the Accumulator (which contains 01) equals the contents of Register 1 (which is 01). If we had entered a 2, the computer would have proceeded from Program step 08 to Program steps 11 and 12. (13 and 14) Program steps 13 and 14 instruct the computer to go to step 66 which starts the multiplication subroutine. (Base * Height = Area of Rectangle) (66) Program step 66 loads the Accumulator with the contents of Register 3 which contains the base (Step 06). We'll use 8 as our example of the base measurement. (67) Program step 67 adds the contents of Register 3 (which contains the base measurement of 8 in our example) to the contents of the Accumulator which now also contains 8. (68) The contents of the Accumulator (8+8=16) are stored in Register 5. (69) The Accumulator is loaded with the contents of Register 4 which contains the height. We'll use 3 as our example. This data was entered into Register 4 in Program step 07. (70) In Program step 70, the Accumulator is decremented by 1. (Remember, in multiplying, the multiplier is decremented by 1 with each addition operation until the multiplier equals 01). (71) The contents of the Accumulator (now 2) are loaded into Register 4. (72 through 73) These instructions tell the computer to branch to Program step 77 if the contents of the Accumulator are equal to the contents of Register 1. (Register 1 = 01). This was accomplished in Program step 02. (74) If the Accumulator does not equal 01 at Program step 72, the Accumulator will move to Program step 75 and be loaded from Register 6 which contains 16. (75 and 76) Go to step 67. The addition process is repeated until the amount in the Accumulator is equal to the value of Register 1. When this condition is achieved, the computer will branch to Program step 77 as instructed by Program steps 72 and 73. (77) The Accumulator is loaded from Register 5. (Register 5 now equals 24 which is the answer.) (78) Program step 78 instructs the computer to return from subroutine. This returns the computer to program step 15 which unpacks the contents of Register 5. Program steps 16 and 17 output the answer to the screen. Program step 18 tells the computer to go to the blanking operation at program step 58. Program steps 58 through 63 output blank spaces that erase the old problem and make room for a new one. Program step 64 tells the computer to return to step 00 and to get ready to solve a new problem. Now we'll see how this program computes the area of a triangle (Base * Height / 2 = Area of Triangle) For our example, we'll use 6 as the base and 2 as the height. This time we will choose 2 (triangle routine) at Program step 08 to load into the Accumulator. Since Program steps 09 and 10 do not apply, the computer will jump to Program step 11. Program step 11 instructs the Odyssey2 to branch to program step 20 for the triangle routine. Program 20 instructs the Odyssey2 to branch to step 66 for the multiply routine. Program steps 66 through 75 perf |