[editor : Carl T. Helmers Jr.] [publisher : Virginia Peschke Londner] [art : Stephen Kruse, Wai Chiu Li, Dorothy Shamonsky, Ellen Shamonsky] [cover : Joel N Wilson] [nota bene : Some missing pages in archive.org. Full version in vintageapple.org] #Magazine
#Abstract
About the Cover: The computer experimenter of the future shown on this month's cover is using a computer graphics terminal created by artist Joel N Wilson to make a point: computer graphics has come of age. Future scenes such as Joel's painting are not far off, and this month's issue is largely devoted to the fascinating world of computer graphics.
Taking photographs of your video display is an inexpensive alternative to buying a printer or other hard copy device for your computer. However, it's not always as easy as it sounds. Dr Dwight D Egbert gives some valuable tips on the subject in The Photograph Is Also a Hard Copy. page 70
Real 3-D graphics? It sounds like an impossible concept, even given the magic of minicomputers, but that is just what authors Timothy Walters and William Harris have created. Read Graphics in Depth : 3-D Adds a New Dimension to Your Display and find out how to create images that change perspective as you vary your viewing angle. page 76
What's the difference between an RF monitor and a direct video entry monitor? Find out in Convert Your TV Set to a Video Monitor. Dan Fylstra explains the relative merits of the two approaches to video displays, and gives you some idea of the techniques necessary to implement both methods. page 22
Would you like to try some pseudocolor? How about an 8 level grey scale? High density video graphics is an exciting application of personal computing. There are many video display boards on the market to help you get started. Read about one of them in The Matrox ALT-256 Video Board, by Gary Ruple. page 24
Color graphics is an exciting branch of personal computing. Ordinary video display programs take on a new luster when converted to color. Authors Thomas A Dwyer and Margot Critchfield discuss the use of Color Graphics on the Compucolor 8051. page 32
Is there a practical microcomputer PASCAL language system? Ken Bowles, of the Institute for Information Systems at the University of California San Diego, outlines what is perhaps one of the most significant software developments of the past year or so: the UCSD PASCAL system now available for LSI-11, 8080 and Z-80 machines and soon to be available for other major general purpose microcomputer systems. Read Ken's account of UCSD PASCAL : A (Nearly) Machine Independent Software System . page 46
A hidden line subroutine for your plotter can make the difference between an average plot and a professional looking one. The algorithms aren't as difficult as you might think . Read Hidden Line Subroutines for Three-Dimensional Plotting by Mark Gottlieb and find out more. page 49
One way to learn more about display systems for television is to read a detailed description of a practical video driver program. John Webster and John Young have done just that in GRAPH: A System for Television Graphics. In part 1, this month, the authors provide background information and begin a detail discussion of this character editing system used for titling and graphics associated with educational videotape production. page 62
Did you ever wish your video display could handle Greek letters, subscripts, different size fonts, or even APL characters? How about special graphics characters? Find out how to add these and many other characters to your video display system in A Programmable Character Generator by Larry Weinstein. page 79
When designing a light wand and signal processor it is desirable to have as few external variables as possible affecting the output. In A Low Cost Light Wand Amplifier, Robin C Moseley examines some of the variables that must be considered and describes a particular signal processor which is tolerant of many external variables. page 92
Last month Steve Ciarcia described the transmitter section of his AC wireless remote control system . This month read the concluding description of the receiver in Tune In and Turn On, Part 2, and start experimenting with your· own computer controlled wireless appliance and light control system. page 97
This month, Jack Bryant and Manot Swasdee complete their description of How to Multiply in a Wet Climate with the details of multiplier hardware and a program to test the multiplier in comparison with an equivalent software multiplication. page 104
[author : Carl Helmers] #Edito
Extract : « By the time you read this, the events of this past week will be history as the seasons progress. Monday evening (Feb 6) it began to snow a bit in Peterborough. It had apparently been snowing through most of the day at places further south along the eastern seaboard, but I had no expectation of anything out of the ordinary. After all, the morning news and weather reports I listened to had said we might get a foot of snow, but that is hardly unusual. One of the reasons for locating one's home and place of business in the hills of New Hampshire is to take advantage of those opportunities for transient beauty which are presented each year by a full cycle of seasons. All six seasons — Summer, Foliage, Winter, Mud, Spring and Black Fly — come and go in a regular cycle each year. Since the first week of February is solidly within the Winter phase of the cycle, another snowstorm is not a major event. [...] »
TABLE OF CONTENTS
[theme : Graphics] [author : Walters-Harris] #Display #Interface #Graphics #Electronic #Listing #Assembly #BASIC #Book
Extract : « Regular readers of BYTE have already seen many articles and advertisements concerning graphic displays. A graphic display adds direct visual impact to the computer output, communicating directly in a nonverbal manner. The advantages of this kind of display in specific applications are obvious. But what about adding a third dimension to the display?
Many drawings are representations of three-dimensional data in two dimensions; with the ability to display in three dimensions it would not be necessary to use perspective or other cues to suggest an impression of depth. Instead, an architectural drawing, Space War, 3-D Life or abstract graphic designs could be displayed directly. An image displayed in this manner would appear to exist in space; viewers could "look behind" the image to a degree and see it from different perspectives by simply changing their viewing angle.
How can a three-dimensional display be built? [...]
[...] REFERENCES
1. Simon, W, "A Three Dimensional Computer Display," Computer Graphics and Image Processing, volume 4, pages 396 thru 402, 1975.
2. Simon, W, "A Method of Producing a Three- dimensional Cathode Ray Tube Display," Behavioral Research Methods and Instrumentation, volume 1, page 179, 1969.
3. Traul, A C, "A New 3-dimensional Display Technique," MITRE Report M68-4, 1968 (AD684252).
4. Rawson, E G, "3-D Computer Generated Movies Using a Vari focal Mirror," Applied Optics, volume 7, pages 1505 thru 1511, 1968.
5. Rawson, E G, "Vibrating Varifocal Mirror for 3-D Imaging," Spectrum, volume 6, pages 37 thru 43, 1969. »
[theme : Hardware] [author : Fylstra]
(missing pages)
[theme : Graphics] [author : Gottlieb] #Display #Interface #Graphics #Listing #BASIC #Mathematics
Extract : « A hidden line subroutine is used to eliminate lines which are behind surfaces and which in real life one would not be able to see in a computer generated plot of a solid object in two dimensions. A hidden line subroutine makes the final picture more realistic. [...] »
[theme : Software, Video Graphics] [author : Webster-Young] #Display #Electronic #Algorithm
Extract : « Our department of Audio Visual Services at the University of New Brunswick makes extensive use of small format videotape recording for instructional and research purposes. Tapes are recorded either in a studio situation or with portable recorders. Most programs are then edited, and require the addition of graphics ranging from simple titles or names superimposed over the picture to more complex charts and graphs that will be incorporated in the final production.
Anyone who watches television will have noticed that electronic character generators are becoming increasingly popular for providing titles, credits and other forms of alphanumeric character displays. Their advantages over the old system of creating the graphics on cards and pointing a camera at them are obvious. Electronic generators are quicker, require no special graphics training or materials, and are, incidentally, cheaper. Electronic titles can also be easily and quickly changed or updated. They also require no dedicated graphics camera and operator.
In examining commercial electronic titling equipment, we found two main disadvantages: Commercial units were quite expensive, and at the same time somewhat limited in their behavior.
We therefore decided to explore the "hobby" computer market and to design our own television graphics generator. [...] »
[theme : Hardware] [author : Weinstein] #Display #Interface #Electronic #Listing #Assembly
Extract : « The truly critical interface in any computer system is the one that joins man and machine. One example of this is the interface between the video display and the human eye, an area where the computer outputs information at a very high rate. One way to improve this interface is to provide for maximum flexibility in the choice of characters displayed. This article presents circuitry for adding software controlled character graphic definitions to existing video display devices.
For many applications, the ability to create the characters that appear on the terminal screen is a tremendous convenience, if not an absolute necessity. The use of computers for advanced mathematical applications often requires special symbols such as Greek letters, subscripts, superscripts and variable sized fonts. APL is a good example of an advanced programming language that uses many special symbols. Computing programs that transform the general purpose computer into the equivalent of a hand held calculator suffer from the lack of a specialized keyset and the corresponding display format. Financial and scientific applications call for their own special symbols. In fact, there are very few computer applications that wouldn't benefit from easy access to a specialized character set. [...] »
[theme : Hardware] [author : Ciarcia] #Robotics
Extract : « Last month (page 114) I outlined the transmitter section of a wireless AC remote control system that can be easily attached to any computer with an 8 bit parallel output port. As previously stated, it will allow remote on and off control of up to ten AC powered devices. This month I cover the design of a typical receiver section. [...] »
[theme : Computation] [author : Bryant-Swasdee] #Listing #Assembly #Algorithm #Electronic #Mathematics
Extract : « This month we give detailed construction information on how to build a wire wrap version of the hardware multiplier for the SwTPC 6800 system. Photo 1 shows the multiplier installed in port 7 of the 6800, which is the object of this effort. We used port 7 because the wire wrap pins would be easily accessible there and would not interfere with other IO interfaces. We begin with some details about the SwTPC mother board address decoding. [...] »
[theme : Video Displays] [author : Egbert] #Graphics #Experience
Extract : « Even with the arrival of low cost alphanumeric printers for hobby computers, there are still several situations in which photographs from video displays are the most satisfactory form of hard copy. This is particularly true when you are displaying graphs or image data in black and white, or with almost any color display. In fact, most professionals working with color displays are still forced to photograph their video displays to obtain color hard copy. At present, satisfactory color hard copy devices range in price from $50,000 to well over $500,000.
Likewise, the current small system printers are not suitable for image data, whether black and white or color. Image data differs from the usual alphanumeric and graphics data because the display is no longer binary (black or white, color or no color). Instead, image data is displayed in a two-dimensional array or raster, and each element of the array or each picture element (pixel) can possess one of several grey levels or colors. In the field of personal computing, the Cromemco Dazzler is capable of displaying image data in up to a 64 by 64 pixel array with each pixel one of 16 possible grey levels or 15 possible colors. The Apple II has a similar mode of operation with 16 colors and black available in a 44 high by 40 wide array. For these types of displays it will probably be many years before a viable alternative to photography exists for low cost hard copy. [...] »
[theme : Graphics] [author : Ruple] #Review #GraphicCard
Extract : « The ALT-256 is an Altair (S-100) bus compatible graphics card that gives a resolution of 256 by 256 dots. This display is useful for professional graphics applications such as computer aided design, simulation, business and educational displays, and plotting curves.
The display memory on the ALT-256 consists of 16 4K dynamic memory integrated circuits in the 16 pin package. The dynamic memory refresh is handled by the video scan circuitry so that no processor time is required for this function. [...] »
[theme : Graphics] [author : Dwyer-Critchfield] #Listing #BASIC #Graphics
Extract : « The ancient wisdom that says "a picture is worth a thousand words" has a special significance for the computer age. With machines that can generate output faster than anyone can read it, there's no doubt that we need new ways to represent this avalanche of data. The best answer (so far) seems to be in computer graphics: sophisticated pictures that show the results of all this computation in a form that is easy to interpret and even easier to remember.
One of the most dramatic ways to improve graphical output is to add color. Color graphics conveys information to human viewers that is hard to appreciate until it's experienced. The change from black and white to color is at least as impressive as the change from monaural to full stereo sound. [...] »
[theme : Hardware] [author : Moseley] #DataEntry #Electronic #Digitization
Extract : « The purpose of this article is to discuss some of the variables involved in the reading of printed bar data, and to describe a signal processor whose operation is independent of most of these variables, and tolerant of the remainder.
For the most reliable recovery of data, the effective aperture of the light wand photodetector should be no wider than the narrowest data bar. In this case, full black to white signal swing is obtained in response to narrow bars, and variables such as lamp output, photodetector sensitivity, pen angle, and target contrast control only two output functions: white level photocurrent and black level photocurrent.
In any light wand having a linear photodetector, the ratio of these currents is determined by the ratio of the reflectivities of the black and white bars, ie: target contrast. The absolute value of the photocurrent may, of course, vary widely between different light wands, even those of the same design. [...] »
Comments on PASCAL, Programming and Small Systems
Comments on APL's Characteristics
Warnier-Orr Diagrams: Some Further Thoughts
#Book
Extract : « The Dragons of Eden by Carl Sagan Random House, New York 263 pages, 6 1/2 by 9 1/2 inches $8.95
Digital Computer Electronics by Albert Paul Malvino McGraw-Hill, New York 1977 393 pages $14.95
The Elements of Programming Style by B W Kernighan and P J Plauger McGraw-Hill, New York 1974 147 pages paperback $2.65
Mortal Engines by Stanislaw Lem translation and introduction by Michael Kandel Seabury Press New York, 1977 $9.95 »
Standardization of High Level Languages
Grappling with GRAPL Some Choice Comments
#Association
