[editor : Carl T. Helmers Jr., Christopher P Morgan] [publisher : Virginia Londoner, Gordon R Williamson] [art : Holly Carmen LaBossiere, Deborah Porter] #Magazine
#Abstract
BYTE is five years old this month, and we're taking the opportunity to discuss one of our favorite subjects: homebrewing. Much of the personal computer hardware sold today is already assembled; even so, many of our readers like to build or modify their own equipment, and even "homebrew" it from scratch. The cover photograph by Raoul Hackel, Stock Boston, shows some colorful wiring harnesses inside a computer chassis, a familiar sight to the intrepid do-it-yourselfer.
Theme articles in this issue include a build-it-yourself, low-cost, remote data-entry terminal (from Steve Ciarcia); exploring the TI Speak & Spell; a pennypincher's joystick interface; and the beginning of a multipart article on building an 8088 processor for the S-100 bus. Along with these are features on threaded code; FCC regulations and your personal computer; machine problem-solving; some tax hints for personal computer owners; and much more.
You've probably noticed that this issue of BYTE is on the large side. In fact, it's the biggest issue we've ever printed. The extra space allows us to bring you even more articles and features in this issue and in the coming months. . . . CM
[author : Carl Helmers] #Edito
Extract : « Recently, I encountered an old problem again. A problem in this sense is a body of questions and my tentative answers. An old problem is like an old jacket. You get familiar with the intricacies of its individual creases, wrinkles, and holes. It may not be currently stylish, or even in the best of conditions. Yet it is hardly worth throwing out because of a shared body of experience. So, I had long ago packed this problem away in my mental baggage.
The problem I refer to is ethical in nature; it has epistemological attributes as well. It is the problem of interfacing the world of ideas with the world of commerce. In its simplest form it is a two-part question: "who originated an idea?" and "what is the value of that idea?" The problem, which has great practical implications in our technological civilization, is that of encouraging innovation by means of rewards in the worlds of ideas and commerce. The ethical position implicit in my viewpoint is simple honesty. Its intellectual expression is that credit should be given where credit is due in a freely operating world of ideas. In a laissez-faire world of commerce, its expression is that value in the marketplace should be given where value is due, in a framework of freely chosen relationships. [...] »
TABLE OF CONTENTS
This terminal increases the flexibility of computer home-control systems.
[author : Steve Ciarcia] #Electronic #Build #ComputerTerminal
Extract : « Remote data-entry terminals are not something new. They are devices which provide a means of direct, specialized communication with a computer. In July's Circuit Cellar I said that a pushbutton switch on the end of a long cable is probably the least expensive and most secure form of remote data entry. This is still true, but now it is time to look at more sophisticated forms of remote data entry.
There is no formal definition of what constitutes a remote data-entry terminal. The application defines the classification. While a regular videodisplay terminal can be used for data entry, remote data-entry terminals are usually specially fabricated to fit the application and environment. Remote data-entry terminals almost always communicate in duplex mode, and are capable of displaying computer directives to the operator as well as sending operator input to the computer. [...] »
Part 1 covers the basic design considerations of an S-100 processor board based on Intel's 8088 microprocessor.
[author : Tom Cantrell] #Electronic #Microprocessor #Interface #Book
Extract : « [...] Intel's 8088 microprocessor is a remarkable machine. By combining a 16-bit execution unit with an 8-bit bus interface, the 8088 can represent the best of both worlds for many users. (See figure 1.) In particular, the 8088 allows you to reap the benefits of a powerful new architecture while preserving your investment in 8-bit hardware. In addition, many datahandling- oriented applications (such as intelligent terminals, data concentrators, and small business computers) are more naturally implemented with a machine that communicates using 8-bit characters. [...] »
For about $6 and one night's work, you can add this interface to your system.
[author : Steven Wexler] #Electronic #Algorithm #listing #Assembly
Extract : « One of the more entertaining input devices that can be operated by a human hand is the joystick. Physically, the device consists of a lever that moves in two dimensions. The lever operates two potentiometers, which translate the position of the lever into two analog resistance values. A joystick hardware interface, in conjunction with the appropriate software, can convert the resistance values into corresponding binary integer values. These integers can be used to move a cursor, alter music, or control a robot, along with a myriad of other applications. [...] »
This is a simple modification for any video display employing the MCM6571 character generator.
[author : John W Langer] #Electronic #Display
Extract : « With the addition of only a few integrated circuits, and with only a single change in your present video interface, you can have the essential APL characters, including overstrikes. The circuit presented here should work with any video display using the popular MCM6571 character generator and can easily be adapted for others. [...] »
Part 2 helps you to complete the construction of the terminal and learn to use the built-in debugging features.
[author : Theron Wierenga] #Electronic #Build #ComputerTerminal #Listing #Assembly
Extract : « [...] The next step is to install the four 2114 memory circuits, IC19 (the 74LS138 that decodes the 2114s), IC13 (the 7401 that is used with the 74LS138 decoder), and IC4 and ICS (the two 8212s that are connected back-to-back to buffer the 2114s). The 2716 must be programmed again, this time with the entire software package that is given in listing 2. [...] »
A practical BASIC program can be used to explore the power and limitations of this new algorithm.
[author : G C Berresford, A M Rockett, and J C Stevenson] #Algorithm #Mathematics #Listing #BASIC #Book
Extract : « A paper published by the Soviet mathematician Leonid Khachiyan received widespread publicity in late 1979 as a revolutionary new solution to linear programming problems. In Part 1 last month, we discussed the details of Khachiyan's algorithm and its corresponding geometric interpretation. This month in Part 2, we will look at the practical problems in using the algorithm and will examine a BASIC program that uses the algorithm. [...] »
This BASIC program helps the target shooter to calculate the complex path of bullets.
[author : Robert W Jenks] #Listing #BASIC #Physics #Book
Extract : « Many sports are intricately involved with the properties of objects lofted into the air and thereby committed to the inevitable effects of gravity. Both players and fans relish golf's hole-in-one, the long bomb to the wide receiver in football, and the horne run in baseball. In the case of target shooting, the path of the projectile is of particular interest. How the bullet gets to the target is the province of physics, but where it lands resides solely in the skill of the shooter. BALISTIC is a program to calculate just where a bullet will go. [...] »
Three selectable interrupt rates make the Texas Instruments 16-bit processor count time.
[author : Thomas G Morris Jr] #Electronic #Algorithm #Listing #Assembly #Time
Extract : « One of the first things many computer enthusiasts feel the need for is a real-time clock for their personal computers. With many different methods available for the computer to maintain the time of day, I decided that any real-time clock should have a reasonably low software overhead and simple hardware approach. [...] »
Here's a complete six-program package keep your budget records in order.
[author : Joseph J Roehrig] #Listing #BASIC #Storage #DataManagement #Finance
Extract : « The purpose of this article is to present a complete accounting system for a microprocessor equipped with a floppy disk or another storage device. This article gives complete listings for all programs and focuses on the operation rather than on the design of the system. The programs are written in North Star BASIC on an IMSAI 8080 system with 24 K of programmable memory. As a model we use a fictitious company (JJR) that used the Micro Accounting System in 1976. During this period the journal entry, balance sheet, budget input and general list programs are introduced. Income statement and budget programs are examined later in the article. The magnitude of the figures used and the number of inputs shown are kept to a minimum for the sake of clarity. [...] »
With these notes you can move toward the eventual goal of getting this toy to talk under personal computer control.
[author : Michael A Rigsby] #ComputerPortable #Audio #HowItWorks
Extract : « [...] Speak & Spell is an educational aid designed for children aged seven or older. It contains a vocabulary of greater than 230 words in addition to the letters of the alphabet. Asking questions and playing games with electronic speech, it expects answers to be entered on its 40-switch keyboard. Each entry evokes an audible response, and the machine even keeps score. Plug-in modules are available to expand the vocabulary. Suggested retail price for the toy is $65, though I bought mine for less than $40 at a major Atlanta department store. [...] »
Simple games help to express this method of solving problems with computers.
[author : Peter W Frey] #Listing #BASIC #ArtificialIntelligence #Book
Extract : « Modern computers are famous for their numbercrunching ability. Their facility at inverting a 60 by 60 matrix or at solving a set of linear differential equations is truly impressive. In fact, machines are so good at solving numerical problems that most of us take these skills for granted.
Computers are also useful as general-purpose control devices. Many personal-computing enthusiasts enjoy impressing their neighbors with their machine's ability to control lights, water sprinklers, and burglar alarms, and to take telephone calls and regulate the furnace. Homes of the future will be completely computerized.
The computer also makes an excellent bookkeeper: faithfully recording financial transactions, maintaining mailing lists, and generating timely reminders for important meetings. Personal computers also provide many hours of entertainment for their owners with games of manual dexterity, games of chance, and simulated battles among the stars or in dark dungeons. These many uses provide a clear rationale for the rapidly developing popularity of the personal computer.
The most exciting application of the computer lies in still another direction. It is as a thinking machine that the modern computer truly sparks our imagination. When faced with a problem that has no easy numerical solution, men have typically discarded their mechanical calculators and put on their proverbial thinking caps. For this type of problem, the human brain has always been superior to mechanical devices. An immense amount of respect for the human brain can be gained by trying to program a computer to select the best move in a game like chess. Even a multimillion-dollar mainframe computer turns out to be a woodpusher when asked to compete against a skilled human player. [...] »
New rulings by the FCC will affect the use and manufacture of personal computers.
[author : Terry C Mahn] #TradeAndLaws #Standard
Extract : « If you have been reading BYTE within the last half year, you are probably aware that the FCC (Federal Communications Commission) has handed down a set of regulations prohibiting the sale of personal computers that emit unacceptable levels of RFI (radio-frequency interference). But the FCC has changed its regulations several times, and in any case, information on and interpretation of these rulings have been scarce. I hope to clarify these most recent FCC regulations and to describe how (and when) they will affect you as a personal-computer user or vendor and the industry in general. [...] »
Some kinds of threaded code are position and system independent.
[author : Terry Ritter and Gregory Walker] #Method #Language #Programming #Listing #Pascal #Assembly #Book
Extract : « Between a high-level language (HLL) and its underlying machine architecture lurk many language implementation techniques. These include the older techniques of interpretation and compilation, as well as newer ones like intermediate languages and threaded code. In this article, we will present four types of threaded code techniques for implementing intermediate languages. We will examine how these four logically equivalent techniques offer various trade-offs of execution speed, program storage, and use of processor resources. [...] »
Children should learn to compute in the same way they learn to talk.
[author : Seymour Papert] #Education #Logo #Mathematics #Graphics #Book
Extract : « I start with an image, more general than the computer, that has helped me to think about how the world takes up any new technology. The first movies were made by setting the newly invented motion-picture camera in front of a stage where a play was performed just as plays always had been. Only after some time did cinema become more than theatre plus camera. When it did, what emerged was something original and unique, a whole new culture with new modes of thinking and new breeds of people-stars, directors, scriptwriters, cameramen, critics, and audiences whose sensitivities, expectations, and ways of seeing were quite different from those of the theatre-goers of the past.
So too with the computer. The first instinct of educators is to couple the new technology to their old methods of instruction. My vision is of something much grander. So I dream of using this powerful new technology not to "improve" the schools we have always known (and, to be honest, hated) but to replace them with something better. I do not believe that this something will look anything like what is now known as "computer-aided instruction" (CAI). I think it will be more like the growth of a new culture, a "computer culture" in which the presence of computers will have been so integrated into new ways to think about ourselves and about the subject matters we learn that the nature of learning itself will be transformed.
In thinking about the nature of such potential transformation, the LOGO group of the Massachusetts Institute of Technology (MIT) Artificial Intelligence Laboratory has been guided by the idea of creating computer-based environments in which mathematics and other areas of "formal" learning can be learned in a natural fashion, much as a child learns to speak; and applying concepts from artificial intelligence to children's learning, to help children become articulate about, and thus gain control over, the learning process. Before developing these ideas, I would like readers to clear their minds of a misleading but common image. People generally think about computers in schools as a scarce resource to which students have occasional access. It is time we learned to think in terms of a computer for every child, and we should think about children having access to computers from infancy. If we think in these terms, we begin to recognize that there is a clear discontinuity between the current ideas about using computers in schools and the situation of the future. I really believe that almost everything being done today is only relevant to the future in that it sets a bad example so that people become accustomed to primitive models. [...] »
#Book
Extract : « Microcomputers and Physiological Simulation, James E Randall, Addison-Wesley, Reading MA, 1980, 234 pages, hardcover, $14.50 [...]
Microcomputer-Analog Converter Software and Hardware Interfacing, Titus, Titus, Rony, and Larsen, Blacksburg Continuing Education Series, Howard W Sams, 1978, 286 pages, softcover, $9.50 [...]
Engineer's Notebook: A Handbook of Integrated Circuit Applications, Forrest M Mims III, Radio Shack Technical Publications, 128 pages, softcover, $1.99 [...]
Microcomputer Interfacing with the 8255 PPI Chip, Paul F Goldsbrough and Peter R Rony, Blacksburg Continuing Education Series, Howard W Sams, 1979, 224 pages, softcover, $8.95 [...]
Thrice Upon a Time, James P Hogan, Ballantine Books, New York NY, 1980, 311 pages, softcover, $2.25 [...]
Noise Reduction Techniques in Electronic Systems, Henry W Ott, John Wiley & Sons, New York NY, 1976, 294 pages, hardcover, $24.50 [...] »