[editor : Carl T. Helmers Jr.] [publisher : Virginia Londoner (Virginia Londner), Gordon R Williamson] [art : Ellen Bingham, Wai Chiu Li, Christine Dixon, Nancy Estle] [cover : Robert Tinney] [nota bene : Some missing pages in archive.org. Full version in vintageapple.org] #Magazine
#Abstract
Robert Tinney's cover painting, "Automating Eclipses", symbolizes this month's theme of computers and weather. See this month's theme articles by Stephen P Smith and Neil Dvorak, and the editorial by Carl Helmers."
When entering large amounts of graph associated data into a computer , a graphic tablet that allows you to digitize the data is a great help. Stephen P Smith uses such a device, the Summagraphics Bit Pad digitizer, to perform the Graphic Input of Weather Data. page 18
This month "Ciarcia's Circuit Cellar" explores the use and interfacing of Texas Instruments and General Instrument sound generators. Find out how you can let your computer Sound Off. page 34
In part 1 of A Model of the Brain for Robot Control, James Albus defined the notation we used for his brain model . This month he describes a neurological model that can store and recall a broad class of mathematical functions. page 54
Much computer art employs the calculating ability of the machine to make drawings expressing mathematical relationships. Kurt Schmucker defines two classes of such drawings and describes methods for producing them in The Mathematics of Computer Art. page 105
To forecast weather, you need to know wind speed and direction. By using modern technology, we can do without whirling mechanical assemblies. Neil Dvorak shows us how to use electronic components and computer programs to measure the wind in Sonic Anemometry for the Hobbyist. page 120
In part 2 of The Nature of Robots, William T Powers presents a BASIC simulation of a control system . By experimenting with this simulator, the reader is able to work with the concepts of a closed loop control system . page 134
Creativity in Computer Music by Hubert S Howe Jr is a survey of some recent work in music theory, analysis, sound generation, and composition done with computers. Microcomputers can now be used for much of the work formerly done by large scale computers a decade ago. page 158
After you have successfully hunted the Wumpus, and destroyed all the Klingons, what is your next step? Roger Chaffee suggests you try your hand in some caves, searching for hidden treasure. Enter the world of suspense and danger on your Quest for riches. page 176
Building a computer from scratch as an amateur is the historical root of the personal computer field. In this issue, Carl Helmers begins an informal series of articles on a new homebrew project: a general purpose 6809 system. The computer itself has an intended application to music, but the design and construction of this homebrew project are quite general. See Photo Essay: Physical Hardware of a New Computer Backplane. page 194
Mouse is a programming language that contains many features usually associated with high level programming languages and can be implemented with minimal resources. It is of interest to people who enjoy obtaining dramatic results with little effort and to those who have a system which is too small to support a conventional high level language. Peter Grogono describes the implementation of Mouse by means of a Pascal program which can be used to write an assembly language version. Indications of how this might be done are provided in Mouse: A Language for Microcomputers. page 198
When working with subroutines, the concept of passing parameters can be confusing. W D Maurer describes three methods of passing parameters (call by value and result, call by reference, and call by name) in his article Subroutine Parameters. page 226"
[author : Carl Helmers] #Edito
Extract : « The idea occurred last fall. An innocuous advertisement appeared in Smithsonian Magazine, trumpeting an exciting adventure called "Eclipse Over Big Sky" which would take place in February 1979 at the Big Sky ski resort in the southwestern part of Montana, near Yellowstone Park in Wyoming. Naturally, I sent away for the information advertised.
After receiving the literature, I made up my mind that a total solar eclipse was worth seeing, especially if it was to be the last one on continental North America for some forty years. So, I sent in my deposit and made plans to attend. It turned out (as I found when I arrived) that this expedition was one of a series of such expeditions organized by sociologist and eclipse buff Dr Phil Sigler of New York City, These expeditions had attended every total solar eclipse for the past eight or ten years. Using the latest in modern techniques, including reference to weather satellite data, they had found a necessary hole in the clouds at the right time in eight out of nine cases prior to this eclipse. [...] »
TABLE OF CONTENTS
Graphical data acquisition techniques
[author : Stephen P Smith] #Algorithm #Listing #BASIC #DataAcquisition #Meteorology #Book
Extract : « The fact that everyone complains about the weather, but nobody does anything about it, is well-known. Weather forecasting is still more art than science.
Manual techniques still yield the best quantitative weather predictions when compared with the largest computer systems processing a wealth of satellite, radar, and ground station data. However even modest data processing equipment can be an important tool for the meteorologist. I'll show how the combination of a small personal computer and a Summagraphics Bit Pad graphics tablet simplifies the processing of rainfall estimates for a regional data base. The application is an interesting one, and the BASIC language software developed will be useful in any system employing a Bit Pad for data entry.
Locally, rainfall can be measured with simple gauges. The heavy showers common during the prime growing and flood seasons have irregular distributions, so local measurements may be inadequate for regional use. Agricultural planners need to know how much rain has fallen over a specific growing area. Hydrologists working on flood warning and control need to know how much has fallen within a given watershed. Both groups need this information broken down into relatively small elements of time and area, perhaps for each 24 hour period and for each 10 kilometer square. To achieve this detail, tools in addition to rain gauges must be used. [...] »
Interfacing a computer to external Sound generation devices
[author : Steve Ciarcia] #Electronic #Interface #Listing #Assembly #Audio
Extract : « [...] I have briefly presented two methods of sound synthesis. While both are simple to implement, it is easy to recognize that the Texas Instruments part is more applicable in dedicated designs while the General Instrument device is for general synthesizer applications. It is not inconceivable that the AY-3- 8910 could produce almost any sound, and it is a natural for use with a music interpreter running on a microcomputer. Perhaps the next famous composer will not direct a 150 piece orchestra but, rather, a trio of microcomputers controlling a bank of AY-3-8910s. »
A hierarchical network that can execute tasks and seek goals
[author : James Albus] #Mathematics #ArtificialIntelligence #Book
Extract : « In part 1 I described how sensory interactive, goal directed behavior can be generated and controlled by a multilevel hierarchy of computing modules. At each level of the hierarchy, input commands are decomposed into strings of output subcommands which form the input commands to the next lower level. Feedback from the external environment, or from internal sources, drives the decomposition process and steers the selection of subcommands so as to achieve successful performance of the task of reaching the goal. In this article I will address questions of what kind of neurological structures are believed to exist in the brain and what kind of computations, memory storage methods, and associative recall effects these structures seem to be performing.
Unfortunately, definitive experimental evidence about the structure and function of neurological circuitry in the brain is extremely difficult to obtain. Neurons, the brain's computing elements, are very tiny and delicate. It is hard to measure what is happening in them without damaging them or otherwise interfering with the flow of information related to their operation. Techniques do exist for measuring the activity of individual neurons and sometimes even observing the behavior of several neurons at the same time. There are also techniques which make it possible to monitor synchronized changes in the activity of large numbers of neurons. [...] »
Measuring wind speed and direction by electronic means
[author : Neil Dvorak] #Electronic #Listing #Assembly #Meteorology
Extract : « Meteorological measurement generally concerns itself with five variables: air pressure, humidity, temperature, wind speed, and wind direction. A single sonic anemometer can sense each of the last three variables. Accuracy and linearity are excellent. Additionally, the actual air temperature is detected in a manner which is insensitive to solar radiation, which can easily heat up conventional thermometers.
In a sonic anemometer, wind vane and rotating cups are replaced with transducers which measure the speed of sound as a function of wind velocity and temperature. Commercially available research grade instruments cost upwards of $10,000, and until recently employed analog computational circuitry.
The arrival of the microcomputer and its associated display techniques makes such a scientific instrument economically feasible as an experimenter's project. As a bonus, data can be logged into memory overtime, averaged, and displayed as desired. A tantalizing option involves the attachment of a fast but inexpensive 4 bit analog to digital converter which enables the instrument to double as an ultrasonic echo radar device. At this time, however, such investigations have progressed only to echoing observations on the time base of a triggered oscilloscope. [...] »
Understanding closed loop control systems
[author : William T Powers] #HowItWorks #Listing #BASIC #Robotics
Extract : « In part 1, we went through a chain of reasoning that ended with the conclusion that the behavior of an organism is not what it seems. Behavior appears to be at the end of a cause and effect chain that starts with the inputs to a nervous system, but that chain is subject to disturbances that can occur after the output of the nervous system. Nevertheless, the behavior at the end of this chain is stable and repeatable, while events closer to the organism become less predictable as we get nearer to the neural signals at the output of the nervous system. By analyzing an example in which a car is maintained in the center of its lane, we saw that this measure of behavior belongs at both the cause and effect ends of the chain, and that if this variable is shown only once in the diagram, a closed loop results.
We are going to look in more detail at the behaving system in this closed loop, to see how it might be organized to produce the results seen. We will start using a simulator written in BASIC which allows the user to vary many parameters of the control system to see the effects on its actions. Human behavior will not be mentioned much in this installment; there are many fundamentals to cover before we can get back to the main purpose of this series. The object here is to retrain the intuition so that the closed loop way of seeing behavior becomes as natural as the old straight through cause and effect way. [...] »
Will you find the treasure or will the giant find you first?
[author : Roger Chaffee] #Listing #BASIC #GameAdventure
Extract : « The preceding paragraphs are taken from a session I played on a computer running a program called Adventure, which has used many, many cycles of machine time on many, many computers in the past year or two. The original version, I believe, was written in FORTRAN, by Willie Crowther (now at Xerox Palo Alto Research Center), and was subsequently modified and rewritten by Don Woods at Stanford's Artificial Intelligence Laboratory.
The version I ran has been bootlegged through several generations, and I'm not sure of its exact ancestry. It requires close to 200,000 bytes of memory on an IBM 370/ 168. Adventure has been translated into PL/I, APL, and BASIC. It is the successor to Hunt the Wumpus and the many Star Trek games.
I hope it is the precursor of more elaborate games which combine computers with fantasy to produce an "electric novel," which the user and the computer write or experience together. Already, a few computers around the country are offering a child of Adventure called Zork or Dungeon, which has a more sophisticated understanding of English, and a whole new set of problems to solve and monsters to defeat. Space War, which used to belong to the "freaks" and the "hackers" (in the hours after the managers went home), is now available in your neighborhood tavern for 25¢ per enemy starship. How much longer will it be until we can each rule our own kingdom and rescue our own fair maidens? [...]
My thanks go to Larry Tesler and Phyllis Cole, of the Peninsula School Computer Project, for their encouragement and technical help, and to Mary Artibee for her help with this article. A tape of the PET version of Quest is available for $9.95 from the Peninsula School Computing Project, Menlo Park CA 94025. »
Simple language to demonstrate implementation processes
[author : Peter Grogono] #Listing #Pascal #Programming #Languages #Book
Extract : « This article describes Mouse, a computer programming language which can be implemented on most microcomputers. The word Mouse is not an acronym, merely an appropriate description for something small and active.
There are many available languages for microcomputers already, so the introduction of a new language warrants some explanation. The justification for Mouse is that it incorporates many features of high level languages, yet it can be implemented without the resources needed by most high level languages. More specifically, Mouse programs demonstrate the use and implementation of arrays, functions, procedures, nested control structures, local variables, recursion, and several methods of passing parameters from one procedure to another. Mouse also embodies some of the principles of structured programming, in that it uses nested, single entry control structures, and does not allow unrestricted jumps. None- theless, Mouse can be implemented on a minimal system consisting of a microprocessor, 4 K bytes of memory, and a terminal.
All of these features cannot be incorporated into a simple language without making some sacrifices. Identifiers in Mouse consist of a single letter, so that a symbol table is not required. Expressions are written in postfix notation, which is more easily interpreted by a computer than the conventional infix notation. Parameters are passed to subroutines as strings, eliminating the need for complex parameter transmission mechanisms. Mouse programs are easier to write than to read, and it is possible to write Mouse programs that are very obscure. Although readability is a highly desirable feature of a programming language, a language cannot be condemned solely on the grounds that obscure programs can result: witness the popularity of APL. The extraordinary thing about Mouse is that so much can be achieved with such a small amount of implementation effort. [...] »
More ways than you ever dreamed possible to give your subroutines the data they need
[author : W D Maurer] #Initiation #Programming
Extract : « If you've written computer programs in any language, you must be aware by now what a subroutine is, although you might not have written any. The basic concept of a subroutine is present in all computer languages, although every language implements it a bit differently from the others. In systems based on the 8080, the 8085, or the Z-80, you write CALL SUB to call the subroutine called SUB. On the 6800 and the 6502, it's JSR SUB, while in BASIC it's GOSUB a where the first statement of the subroutine SUB is on line number a. But regardless of the language, the concept is the same: you have something in your program that you want to do more than once. It may be looking up an element in a table; it may be printing out a list; it may be making an access to a data structure; but whatever it is, you need it at various times in your program. You don't want to have to write out the same instructions over again every time you need that particular job to be done, because this is wasteful of memory space. So, therefore, you group together the instructions that do this job into & subroutine, and then, at any point that you want the job to be done, you put in an instruction to call the subroutine. When the subroutine is finished, it returns to the point immediately following the place where it was called; and this is also done differently in different programming languages- one writes RETURN in BASIC, RET for the 8080 and Z-80, and RTS (return from subroutine) for the 6800 and 6502.
All this is fine if the job you want to do repeatedly is exactly the same every time you want to do it. But, in practice, this is usually not the case. For example, if you are looking up an element in a table, you are probably looking up a different element each time. If you are multiplying two 16 bit quantities - a very common subject for a small system subroutine - the quantities you are multiplying are probably not the same from one multiplication to the next, and the result is also probably not the same variable. This is true even though the logic of multiplication does stay the same. It is this that has led to the idea of subroutine parameters, the subject of this article. [...] »
Plotting figures that express mathematical relationships
[author : Kurt Schmucker] #Mathematics #Graphics #Book
Extract : « Computer scientists and personal computer enthusiasts have a great appreciation of the beauty and form of art. They often use the tools of their trade, the computer and its associated peripheral devices, to create works of art. These works express particular, somewhat algorithmic and mathematical tastes in art forms. Since the late 1960s the use of computers and computer controlled devices for the generation of this artwork (often in three dimensions) has been firmly established. (See references 3, 4, 8, 9, and 14.) A great portion of this artwork has relied heavily on the computer's ability to precisely manipulate numerical quantities to produce drawings or sculptures that express complex mathematical relationships. Drawings in this category include figures which show the relationships between the phase, amplitude, and periods of different trigonometric functions; graphs of functions of two or more variables; and moire patterns that can express complex relationships by interaction between families of similar simple curves (see reference 13).
This is not to say that all or even the majority of computer art is inherently mathematical. Two of the latest crazes in computer art, the recreation of natural scenes and the randomly drawn picture (called "controlled serendipity" by one artist in reference 11), are in essence nonmathematical. This article, however, will be concerned only with those figures which have mathematics as their basis. [...] »
Effect of computer use on music composition and theory
[author : Hubert S Howe Jr] #Listing #BASIC #Audio #Glossary #Book
Extract : « The most important result of computer applications in music is that they have encouraged a variety of new ideas to be formulated, tested, and reformulated in a short period of time. Concepts that previously would have taken much longer to develop and verify have already been brought forth. Musical thought is consequently on a higher level today. This applies to all aspects of work with computers — as much to research as to creative work, but perhaps less to music than to some other fields. The increasing availability of microcomputers can only further this trend.
The distinction between research and creative work is artificial, for much research is creative — certainly when it pursues new ideas. Computer work in music has for many years been carried out in the creative areas of musical composition and sound synthesis, and the research areas of musical analysis and music theory. In this discussion I will not consider such areas as music bibliography, music printing, CAI (computer assisted instruction), and related disciplines. While much important work has been done in these areas, they are not generally concerned with creative or conceptual problems. Music bibliography essentially involves an information storage and retrieval system. Music printing is a problem of automation. CAI certainly encompasses creative work, but thus far only the most rudimentary instructional tasks have been delegated to computers, and then only with limited success. [...] »
The beginnings of a homebrew 6809 personal computer
[author : Carl T Helmers Jr] #Electronic #Experience
Extract : « As noted in a recent editorial, I am in the process of designing and building a new computer system based on the 6809 processor. It is my intention, as this design evolves, to provide a fairly complete set of plans in the form of an irregular series of articles in BYTE. The building and developing of the software systems of homebrew computers is, after all, the basis from which personal computing has developed. This series of articles will document the development of an up-to-date design that utilizes contemporary components which were unavailable to me when I first started building crude and imperfect homebrew computers in 1974. [...] »
#Assocation
#Book
Extract : « Top-down Structured Programming Techniques by Clement L McGowan and John R Kelly Mason/Charter Publishers Brown University, New York 7975 288 pages hardback $15.95 [...] »