The growth ofcomputer graphics is remarkable even by computerindustry standards. This first ofa two-part article views some of the
latest hardware available from leading graphics manufacturers.
InteractiveComputer Graphics:
FMng High-Part IWare Myers
Computer Staff
Computer graphics has taken off. That, at least, SIGGRAPH '79, which will be held next month,seemed to be the consensus view of readers ofthe arti- August 8-10, in Chicago at the Hyatt Regencycle "Computer Graphics-Poised for Takeoff" which O'Hare Hotel and the adjoining Exposition Center.appeared in the January 1978 Computer. Reinforcingthis opinion are the estimates of such market re-search firms as Frost and Sullivan of New York and Behind the graphic display is a modelCreative Strategies International of San Jose. Ac-cording to F&S, there are 163 graphics suppliers in In many applications of interactive computerbusiness today.' Creative Strategies estimates that graphics, "whatyou see iswhat you get." The displaycomputer graphics is a half-billion dollar industry itself, or a hard copy, is essentially the end product inwith a 25-percent growth rate.2 Speaking at a recent animation, art, cartography, and data plotting. OfFrost & Sullivan seminar in New York, consultant course, the display is represented in the computerCarl Machover estimated the installed base of and its memory by some kind of model. But if thegraphics terminals through 1978 at 50,000 units- display itself is the purpose, the model need not be70 percent of them in this country. According to geometrically precise. Who cares how big MickeyMachover, at least a dozen suppliers do $10 million or Mouse's ears are, where they attach to his scalp, ormore per year-whereas a decade ago no supplier ex- what the tolerance between ears and scalp should be,ceeded that volume.3 as long as Mickey looks all right to the artist?Supporting this point of view was the attendance In designing a three-dimensional part to fit tightly
at the Fifth Annual Conference on Computer into a larger assembly, however, the designer caresGraphics and Interactive Techniques (SIGGRAPH very much about these matters. Consequently, the'78)-substantially up over prior years, as shown in graphic display of the part has to be backed up in theTable 1. By the end of the conference vendors had computer by a "geometric model."committed for double the amount of floor space at
More than an image. A geometric model is theTable 1. mathematical representation in a computer, not of
Siggraph's rapidly growing attendance figures support the graphic display, but of the actual object of whichthe belief that the computer graphics field Is taking off. the image is a reflection. The mathematical represen-
tation establishes the exact shape of the object bySIGGRAPH NUMBER REGISTERED* NO. OF BOOTHS means of the equations of analytical geometry.Philadelphia 76 350 10 From the viewpoint of a user, a geometric model isSan Jose 77 750 44 developed by inputting to the graphics system threeAtlanta 78 1100 Conference 90 classes ofcommands whichmaybe either interpreted
450 Tutorials or compiled. The first class identifies, or causes to be*Does not include the thousands (in 1978) who visited the exhibits only and generated, primitive volume elements, such as cubesdid not register for theconference. or spheres. The second class scales, rotates, or posi-
tions the primitives in space, and the third class com-bines the primitives by union, intersection, or dif- Vendor forum attracts crowdference. These classes of inputs are in themselves a The formal side of a conference consists mainly ofprocedural description of the shape being developed oral presentations. Similarly, an exhibit consists of aby the user.4 lot of salesmen gradually getting hoarse trying to com-After these inputs are computed, they become the municate above the din. SIGGRAPH '78 tried a new
evaluated description of the shape. This version may departure-organized presentations by vendors. Itremove hidden surfaces or shade other surfaces, an devoted an entire evening to a vendors forum, chairedadvantage in viewing the design. Of greater advan- by Dick Mueller of Control Data Corp. Several hundredtage for engineering purposes, however, is the fully participants, after a long day in the conference roomsstructured description in which faces and edges are and on the exhibit floor, showed up to hear and ques-explicitly represented. tion the senior representatives of a dozen vendors.Then, if the same highly structured representation First at bat was Peter J. Shaw, director of marketing
is used for the primitives in the first place, they, for Megatek Corp., San Diego. He discussed the newtogether with the partly finished shapes or completed Megraphic 5014 Refresh Graphics Terminal, designeddesigns can all be stored, retrieved, drawn, or other- to replace and to be upwardly compatible withwise operated on by a single set of procedures. The Tektronix's 4014 storage tube terminal. Andersprogression from the initial procedural description to Vinberg, director of development and market planningthe evaluated description can be handled with a for Integrated Software Systems Corp., San Diego,single data structure.5 discussed the utilization of DISSPLA and TELL-A-
Singledata estructure.n geometricformulations GRAF software for business and scientific applica-Some of the common geometric formulations in- tions. Other speakers described what was new atclude lines, arcs of circles, ellipses, parabolas, conics, Mathematical Applications Group, Inc., of Elmsford,Bezier curves, polynomials, splines, parametric N.Y., Houston Instruments of Austin, Texas, and Im-curves, and related surfaces and volumes.6 With a lac Corp. of Needham, Mass., as well as other com-precise mathematical representation of an object, it panies.is possible to go on to further analysis. Busy conference delegates at SIGGRAPH '79 gotMechanical engineers realize that the pictorial the chance in a couple of hours to discover more about
aspect of an engineering drawing is just the first step commercial developments than they could in a wholein design. Beyond the picture comes dimensioning day on the exhibit floor. Later they could zero in on(including the determination of which lengths to those exhibits of special interest. Vendors had the op-defineandwhichonesaretofalloutfromthesedefini- portunity to expound upon the key points of theirtions), tolerancing, and attribute specifying (such as stories in a systematic way to several hundred in-surfacefinish).Also,givenaprecisemodelofapart,it terested parties at one time, probably reducing theis apparent that stress, weight, and aerodynamic hoarseness the next day. This year's conference inbehavior could be computed. Tooling to manufacture Chicago will have an expanded vendors' forum inthe part could be derived. From the part's bill of parallel with the technical sessions.materials, material and production planning couldproceed, all still within the computer. However, com-plete computer-aided design and manufacturing space of millions of records at disk speed; doing sorepresent an ideal whose realization is still some will involve a large data base system.decades away.There are many reasons for this rather pessimistic Five elements needed. What seems to be needed to
prospect. One fundamental problem-in the judg- make computer-aided r.'sign complete are fivement of Voelcker and Requicha of the Production elements.Automation Project at the University of Roches-ter-is the "almost total lack of abstract understand- (1) A graphic interface built on top of, rather thaning of design and manufacturing procedures."' As into, the basic modeling system. This element drivesthey put it, "the discrete goods industries run on cen- the graphic hardware.turies of experience, human skills, and knowhow; (2)A data structure that supports thegraphic inter-there is no underlying base of science." face and, in turn, derives its support from the third
Another reason is that geometric modeling of com- element. The data structure should be able to run onputer-displayed images is not very far advanced. Ex- an inexpensive computer system and still keep upisting systems are mostly at the picture stage. Ac- with an interactive designer. To meet this require-cording to Hillyard and Braid, "they model shapes ment, the data structure may be just the picturebut give no precedence to particular lengths or aspect of the full geometric model.angles, nor do they characterize precision (3) A geometric model carrying not only preciseexplicitly."8 spatial definitions but also dimensions, tolerances,Athay points to the "massive change of scale" in and attributes. This model, being complex, will re-
going from a picture representation to a geometric quire-model.9 In the first case the few thousand records can (4) The techniques of data base management, tech-be accessed in main memory through simple run-time niques made all the more necessary by the fact thatroutines. In the more complex case the model records the model has to link one way to the display and themay have to be identified and referenced in a memory other way to-
July 1979 9
(5) Design-analysis programs (stress, etc.) and tinuum. For example, two-dimensional models aredocumentation procedures. simpler to handle than three-dimensional ones. Com-
ponents that can' be described in terms of straightAnother way of looking at the research needed is to lines and flat planes are simpler to handle than those
view geometric modeling along a complexity con- with curved edges and sculptured surfaces. A fewcomponents inanassembly are easierthanmany, andso on.Up to the level of sculptured surfaces, considerable
theory has been worked out and embodied in prac-tical systems. At the level of complex combinationsof simple geometries, called volume modeling, For-rest selected as perhaps the most influential systemsPADL, .developed by Voelcker and his associates atthe University of Rochester; BUILD, by Braid andothers at Cambridge; and TIPS, by Okino and his col-leagues in Hokkaido.10 In his SIGGRAPH '78 paperForrest went further, dealing with the problems ofmodeling complex assemblies of complex com-ponents. One of these problems is how to handle com-plex assemblies of sculptured surfaces; another is ex-tending 'the number of geometric types used involume modeling.'
A. 0. Smith has installed what It calls awalk-in computergraphicsworkstation in fourof its offices. The station encompasses aTektronix4014 Better work in colorgraphics diplay with a digitizer tablet and hardcopy unit. The systemuses A. 0. Smith's Grafax, a pre-and post-processing graphics pro- Color television is found in almost everybody'sgram for NASTRAN. Grafax functions include digitizing the geometry hoof a model from scaled drawings on the graphics tablet; producing line home, and its use is growing in computer graphics.graphs, listings, one-page summary reports of displacements, con- Not only can more information (in a Shannon sense)straint forces, element forces, and element stresses generated by be displayed in color, but a color display seems to itsNASTRAN; calculating or recovering beam stresses; and drawing and users to be sharper. As one user put it, "We can doverifying the geometry of the NASTRAN model. better work in color."
Ramtek commits to color. Firmly convinced of theimportance of what it calls "colorgraphics," Ramtekexpects sales in this area to exceed $100 million by1980, with true raster-scan or bit-per-element unitscontributing $65 milion. In comparison, Ramtekprojects total graphics terminal sales at $350 millionin 1980.Ramtek says that it has been positioning itself for
this marketplace since the introduction of its first col-or terminal, the Micrographic, in 1977. In 1978 it add-ed several more and claimed to be "the only companythat offers the most advanced color displays to allthree price segments of the market."The Ramtek61k10, at $5500, is said by the company
to be the lowest priced bit-per-element color raster-tected byscan terminal on the market; it offers eight colors on a
320 x 240 x 3 matrix on a 13-inch color monitor. Thehegher-resolution 6200A extends the matrix to 512 x256 x 3 for $9950. The top-of-the-line 6310 displays amatrix of 800 x 600 x 3 on a 19-inch color monitor;costing $25,000, this unit provides zoom and panover a 1024 x 1024 x 3 memory.
The Ramtek 6200A Colorgraphecs display terminalis the heart of anelectronic warfare tactics analysis program developed by theWalterV. Tektronix adds color. Few challenge the notionSterling Co. of Orange, Californiao, for war games. The user can that Tek has more terminals-mostly direct-viewsimulate an airstrike force armed with bombs or missiles, and pro- storage tubes-in use than any other vendor. So intected by jamming or chaff, attacking various defense scenarios, such December 1978 when it began to ship a high-perform-as radar and antiaircraft guns or missiles. "Color was of the utmost Im-portance," said Dave Williams, one of the system's designers. "The ance raster-scan color display, observers felt that theuser can Infer much more from the data presented on a color terminal imnportance of color had been certified by the leader.than from the data presented on a standard graphics terminal." The 4027 color graphics terminal, priced at $8695
10 COMPUTER
($7995 to OEMs), is aimed at the middle price seg- entirely inside or outside apolygon appear in the soft-ment of the market. ware display list as spaces; they are not stored bit byWith a 640 x 480 matrix, the refresh memory re- bit. Only those cells that contain graphics informa-
quirement for an 8-color display (3 bits) would have tion-i.e., the cells through which the lines of thereached nearly 120,000 bytes. The basic 4027, polygon pass-are stored in the graphics memory.however, contains only 48,000 bytes of graphics The display list and points are used to allocate thesememory, helping to reduce the price to the middle cells to graphics memory.12range. To reduce the amount of memory, several in-genious ideas have been employed.One is the use of what Tektronix calls "virtual bit Real time animation. With the same high resolu-
mapping," first developed for the 4025 black-and- tion as the Tektronix 4027-640 x 480- the Threewhite alphanumerics/graphics terminal. This tech- Rivers Computer Corporation's CVD/2 color videonique uses software to reduce memory by restricting display features a picture data compression schemegraphics to a rectangular region comprising only part which makes it possible to generate an animated col-of the screen, relegating the rest to alphanumerics. or cartoon in real time from data stored on disk. Com-The second idea involves the division of the pressed data can be transferred from disk and then
graphics region into graphics cells the same size as decompressed at a rate sufficient to support anima-the alphanumeric cells-8 x 14 pixels. Cells that are tion at 10 to 20 frames per second.
s a, c_-
These two pictures, taken from one of Aydin Controls'family of display terminals, make a necessary point abouitrelatively low resolution raster-scan units: The upperphotograph, consisting entirely of vertical and horizontallines, is sharp and the lines are even. Below, thephotograph of a set of off-scan-line curves reveals thestairstep effect resulting from the regular grid of rasterdots. However, the company's Model 5216 display family, These two views demonstrate the color capability of thefeaturing hardware and software modularity, may be con- Tektronix 4027 color graphics terminal. The map of thefigured with resolutions as high as 1024 x 1024, greatly United States (above) contains 36 colors; the floatingreducing the jagged effect, or as low as 256 x 256, where sombrero on a pink cloud (below), actually generated by athe effect would be marked in certain types of work. sine x program, exhibits gradations of over 20 colors.
July 1979 1
The picture data is compressed by a technique called with the painting electron beams. But averages arerun length encoding. In this technique a single deceptive, and sometimes a series of run dodesmemory reference describes a number of pixels along averages fewer than six pixels. The way out is sup-a scan line that have the same color-i.e., a single run piled by a high-speed 1024-word first-in first-out buf-code specifies a color and the number of pixel times it fer.is to be repeated. A sequence of run codes describes This buffer is filled before picture display startsthe various colors along a scan line, and so on for all and is able to transfer data fast enough to keep pacethe scan lines of a frame. with the pixel rate. During horizontal retrace andExperience has demonstrated that the compres- untextured picture areas (little change in color), the
sion ratios for many types of pictures are in the 20:1 buffer has the opportunity to catch up. The decom-range, and 30:1 is not unusual. However, the data for pression logic that translates the run codes into videopictures with very high spatial frequency-i.e., with output is implemented with special-purpose high-frequently changing color-may compress little. In speed hardware.fact, if the color changes every pixel, the run codes Thus, ordinary disks have sufficient bandwidth totake more bits than a frame buffer takes. update the display memory in real time. AIn a conventional frame buffer color display, a 176-megabyte disk, for instance, can hold a 15-
group of bits, usually 3 to 8, is used to specify the col- minute, 11,000-frame cartoon (at 12 frames per sec-or (or gray scale) of each pixel. Thus, in a 640 x 480 x 6 ond). In addition to cartoons, the CVD/2 is useful inmatrix, such as that of the CVD/2, 1.84 megabits other applications demanding the transfer of greatwould be required to store the data for one frame. amounts of information from storage to the screen.Moving this much data for 12-times-per-second ani- The CVD/2 with 16K words of double-ported re-mation would require a 22 megabit-per-second band- fresh memory and PDP-11 interface is $14,000.width-much too high for conventional digital bustransfer rates. However, using run length encoding,cartoon data compresses to about 0.1 megabit per High resolution in Britain. The Coinuter Aidedframe and the transfer bandwidth drops to about 1.3 Dsgn resat CamBritain. ber dedmegabits per second. Design Centre at Cambridge, England, began devel-
In the CVD/2 the run codes are written into one opIng visualization software in 1973, but soonport of. adouble-portedisplaymmorybyheh learned that whereas line drawings could be suc-port of a doubled-ported display memory by the host cafiydslydo ag feupette
computer (a PDP-11) or a disk. The display generator cessfully displayed on a range of equrpment thenfetchesthecode thog th seon pot,fren. h available, the display of shaded pictures was morefetches the codes through the second port, freeig the difficult. They decided they needed a display system
host computerbus. T ,the c uter or te disk that would be faster, have greater picture capacity,can be supplying data for the next frame while ther
. .. ldisplay generator is decoding the run codes and permlt direct viewig, and produce full color.3 Therefreshing the screen with the current data, result was a system composed of six principal units,With 120-nanosecond instruction processing time in addition to a host computer:
and 360-ns main memory access time, the CVD/2takes 480ns toinpr moryacessatrude,.Snepe.d (1) Controller: a hardwired microprocessor havingtakes 480 ns to process a run code. Since pixel draw- an instruction time of 100 nanoseconds;ing time is 80 ns, a run code has to specify an average (2) Frame buffer: 1,572,864-bit MOS RAM havingof at least six pixels, if the main memory is to keep up a c
a cycle time of 400 nanoseconds and capable ofholding a 1024 x 512 x 3 matrix;
(3) Display processor. a unit that accesses theframe buffer via a bus and generates the picture;
(4) Color TV monitor: a display for direct viewing,-| _ operating at the British standard, 625-line interlaced
scan at 25 frames per second;(5) Color cine recording: equipment for animation,
used when image computing time exceeds the framedisplay period;
(6) Monochrome TV: monitor for observing the pic-ture during cine recording.
Four modes of operation trade off resolution andcolor (all modes display 512 lines):
Forecast of sources of US oil supply, depicted on a Three intensityRivers CVD/2 color video display at 640 x 480 resolution, combinationsshows smooth fleld edges at every angle. The 64 colors 24-bit mode 128 pixels/line 16 million hueusable at one time are selectable from a palette of 32,768 and intensityhues. combinations
12 COMPUTER
The transfer rate of uncompressed data exceedsGenerating simulated pictures 37.5 million bits per second between frame buffer and
display processor-a rate that suggests the need forIt is evident that scenes generated on CRT monitors to train ship data compression. For future development the centre
andaircraftpilotsandweaponsaimersandtrackerscannotbeiden- considered what it calls a hardware line-segmenttical to the reality in which these professions work. However, ac- generator that would allow runs of the same pixel tocording to Marconi Radar Systems Ltd. of New Parks, Leicester, if be specified by a single word. Another data compres-the right action cues are incorporated in the simulator, the transfer sion scheme which it calls a hardware quadrilateralof training from the simulator to the real operation does take place. generator would improve performance, it says, byGiven the firm's extensive experience in designing and building "one or two orders of magnitude."simulators, it is instructive to note how much detail the companythinks It must create to make its displays effective. Ultra high resolution. As suggested by the matrix
sizes of the products discussed above, broadcastr CONTENTS television standards place a limit on the number ofSIMULATION SCENARIO OF PICTURE PICTURE picture elements and thus the position resolution ofCOMPUTER COMPUTER GENERATOR the picture. To achieve better resolution, it is
necessary to depart from broadcast technology. Elec-VIDEO tronic Image Systems, a division of Systems
SIGNALS Research Laboratories, Inc., has done so. By oper-OWN SHIP
ating at 34,000 horizontal scans per second, moreOWNRSHID OTHER SHIPS than double the broadcast rate, the SRL model 374 is
CONTROLS CONTROLS DISP able to display 1024 x 1024 pixels. Of course, this(TRAINEE) (INSTRUCTOR) operating speed requires much higher quality in the
display electronics than broadcast type monitorsneed. Even so, at 1024 x 1024 resolution the 374 can
In the Marconi ship handling simulator, the performance character- refresh the screen at only a 30 Hz rate, resulting inistics of the ship the trainee is handling are modeled mathematical- . . .
a
ly in the simulation computer. As the trainee manipulates his own some flicker. However, this flicker is diminished bybridge controls, the computer continuously updates the positon 2:1 interlacing. Electronic Image Systems terms thisand heading of the ship. The scenario computer contains a configuration "ultra high resolution." By sacrificingmathematical model of many square kilometers of islands and sea; half the resolution (going to 1024 x 512), the 374 isit calculates the appearance of the scenery as seen from the various able to refresh at a 60-Hz frame rate, entirelypositions of the training ship. It also calculates the location ano ap- eliminating flicker.pearance of the other ships, which may be following pre-pro-grammed routes or may be controlled by the instructor. These two The video bandwidth capability of 45 MHz (22 nscomputers create the contents of the scene, which the picture per pixel)- more than four times greater than broad-generator turns into video signals. cast standards-assures that the display resolution
is limited by the capability of the CRT, not the elec-As shown in the block diagram, a typical simulator includes a tronics. The 20-inch color tube has a color-dot-trio
computer to keep track of the trainee's own vehicle, one to manage spacing of only 0.31 mm. However, the 374 is not athe surrounding scenery, and a picture gnerator to supply the color complete graphics terminal; it must be connected to adisplay. Although only two computer functions are diagrammed, signal source. Technological capabilities such asthe actual computations are executed by a large number of thoseofthe374exactaprice:$20,800foroneunitandmicroprocessors, designed and programmed in work in parallel. $11,200 in quantities of 51-100.Parallel operation is necessary to provide the amount of detail Mar- In March 1979 Ramtek Corp. introduced the micro-coni considers necessary. processor-based RM-9400 family of raster-scan colorThe computers are capable of modeling from 1000 to 5000 graphics display systems in six resolutions, ranging
"faces," the triangular unit of scenery, and of displaying from 400 to from 512 x 512 to 1024 x 1280 pixels. The higher per-2000 of them at one time. The computers also generate a larger pic- formance members of this series are in the ultra-highture than actually appears on the screen in order to avoid delay In resolution range-a 1024 x 1024 x 8-bit system, forcreating new scenery when the vehicle turns. They also vary the ap- example, with the usual options costing aboutparent light and contrast of the surfaces, depending on the time of $52,000, plus about $10,000 for Ramtek's 40-MHzdayornightandtheamountof fogorhaze. Theyevensimulaterain- 19-inchi000-line color monitor. At this resolution thedrops sliding down the lens of aiming or tracking equipment. sytmoeasat3Hzrfshrqunyie-The picture generator provides the red, green, and blue video system operates at 30 Hz refresh frequency inter-signals for the color display at a 625-line, 50-Hz rate. Color can be laced; at lesser resolutions the refresh rate is 60 Hz.changed upto350times perscan line. Upto64colorscan be in use The capability of applying as many as 128 bits toat any one time out of 262,144 shades potentially available. Using the Z axis provides an enormous range of color huesthree adjoining screens, a field of view of 110 x 30 degrees can be or shades of gray. The Z bits are derived simultan-provided. An edge smoothing technique removes the staircase ap- eously from one to eight groups of 16-bit memories.pearance of oblique lines. Users involved in satellite image processing areAt a time when simulation is becoming more important, because beginning to need high color resolution capability.
of the cost, time, and risk of operational training, Marconi is acting The RM-9400 is able to address a very large "vir-on the belief that improving the quality of the view the trainee sees tual picture coordinate system"-32K x 32K. Withinincreases the transfer-of-training coefficient. this addressing range, a bit matrix approximately
the screen size is implemented in memory. From this
14 COMPUTER
Weighingonly28pounds, theBantamCRTfrom Perkin-ElmerCorpora- Test pattern generated on a CPT Corp. HRD-15 high-tion's Terminals Division is compact enough to sit on a desktop. One resolution high-density 15-inch black and white CRTreasonforitscompactnessisitsfourth-generation LSIcontroller.This demonstrates the visual quality that is obtainable by acustom chip differs from other controllers in being both a 1024 x 768 raster.microprocessor and CRT controller.
matrix smaller pictures may be applied to windowson the screen.These high prices-in fact, the prices of all the color
terminals-contrast with the $599 price (in quan-tities of 100) of Perkin-Elmer's model 550 Bantam.This terminal is black and white, operates withinbroadcast limits, has an upper and lower case charac-ter set built in, but lacks graphics capability. Never-theless,it indicates how inexpensive a terminal thatdraws upon the television tradition can be.
Tricolor display improves data interpretation. Forapplications in which dense data must be interpretedrapidly, such as process control, the beam penetra-
The Hewlett-Packard 1 338A tricolor display permits users to code in- tion phosphor technique offers an alternative to othercoming data in three colors, as in this radar air traffic simulation. The color methods. In the Hewlett-Packard model 1338Acolor distinctions enable a tower controller to interpret the data more tricolor display, three color hues are generated byrapidly and more accurately. rclrdslythecorhusaegnaedb
varying the CRT post-accelerator voltage. The dif-ferent voltages penetrate the phosphor to differentlevels, causing red, green, and yellow hues to be emit-ted.
The beam penetration technique provides higherresolution than comparable raster-scan displays.Because a shadow mask is not used, the color dotsmay be placed anywhere on the screen.
Color changes are initiated in as little as 100microseconds, permitting up to 600 color blocks ofdata per second to be switched.
The 1338A is a 178-mm (7-inch) diagonal, stand-alone, X, Y, Z display. The three orthogonal inputsare analog and the color switching is TTL-compati-
The red, green, and yellow pattern wheels indicate the high resolution ble. The display interfaces with the 1350A graphicsattained by the Hewlett-Packard 1338A tricolor display. The company translator to make a color graphics system. The XIs recommending Its new product for instrumentation, simulation, and Y bandwidth is greater than 3 MHz and thecomputer-aided design, and other applications where the high density Z-axis rise time is less than 30 nanoseconds. Price isof data tends to make Interpretation difficult. $4750.
16 COMPUTER
High resolution black and white 6. Sylvan H. Chasen, Geometric Principles and Pro-cedures for Computer Graphics Applications,
The CPT Corporation, Hopkins, Minn., has achieved Prentice-Hall, Englewood Cliffs, NJ, 1978.specifications well beyond TV levels by careful atten- 7. Herbert V. Voelcker and Aristides A. G. Requicha,tion to design details and use of the latest state of the "Geometric Modeling of Mechanical Parts and Pro-art.TheHRD-15non-interlacedCRTdisplaymodule cesses," Computer, Vol. 10, No. 12, Dec. 1977, pp.operates at a bandwidth of 105 MHz and a scan rate 48-57.of 64,000 lines per second, providing a raster matrix 8. R. C. Hillyard and I.C. Braid, "Characterizing Non-of 1024 x 768. Ideal Shapes in Terms of Dimensions andAt 60 frames per second, flicker is virtually Tolerances," Computer Graphics, op.cit., pp. 234-238.
eliminated, enabling the screen to be viewed eight 9. RussellJ. Athay, "Object Models for Computer Aidedhours per day without eyestrain, according to the Design: An Overview," ibid., pp. 239-244.company. Dot resolution of 0.01 inch is clearly de- 10. A. R. Forrest, "Recent Trends in Computer-Aidedfined by rise/fall times of less than 3 nanoseconds. Geometric Design," Proc. Int'l Conf Interactive
Priceoftheemodel H is $905 t OEMs. The Techniques in Computer-Aided Design, Sept. 21-23,Price ofthe1024-line ~~~~~~1978,pp. 141-146.800-line model S is priced at $810. Both units must besupplied with the video stream and horizontal and 11 , "A Unified Approach to Geometrical Model-
ling," Computer Graphics, op.cit., pp. 264-269.vertical sync.Image Automation, Inc., of Santa Clara, Calif., 12. Ken Willett, "The 4027-Adding a Color Dimension to
adds a high-resolution graphics memory to the CPT Graphics,"Tekscope, Vol. 10, No. 4, 1978, pp. 3-6.display module. Built from 200-nanosecond 16K 13. "Raster-Scan Colour Graphics Display,"Computer-MOS RAM chips, the GMDM-1000 series contains Aided Design, Vol. 9, No. 4, Oct. 1977, pp. 291-294786,432 bits, or 49,152 words of 16 bits. Each bit (published by IPC Science and Technology PressLimited, IPC House, 32 High St., Guilford, Surrey,represents one displayable picture element in black England, GU1 3EW).and white.The graphics memory display module interfaces
via a bus to a host computer. Hosts currently sup-ported include theDEC LSI-1 1 and ZilogMCZ (Z-80).Price is on the order of $10,000, including the powersupply.The program-controlled host computer, using its
I/O functions, writes and reads the individualmemory words. Three Boolean functions-AND, OR,and Exclusive OR-are supported. The entire bitmap can be set to all zeroes or all ones by a single com-mand. A bit mode, useful for vector graphics, permitsmemory bits to be accessed individually. * _U A
Minimum Performance of STIOI-GThis is the first part of a two-part article. Nextmonth 's installment will cover methods employed to ,,achieve the appearance ofbetter resolution, high-per- ,formance vector displays, applications of the corestandard, and developments in plotters. v-
' 1 Sl-- I / -LO
15 P' u,eciReferences
14 Oa
1. Computer Graphics Software & Services Market,Report #653, Frost & Sullivan, New York, Feb. 1979,p. 5 II 1. 0J
3. William Nisen, "Graphics Market Seen Finally Ripen-ing," Computerworld, Vol. 13, No.21, May 21,1979, p.67.
4. Ian C. Braid, New Directions in Geometric Modelling,Computer-Aided Design Group Document No. 98,University of fCambridge, England, Mar. 1978, 33 pp.
5. ___, "On Storing and Changing Shape Informa- |j#tion," Computer Graphics, Vol.12, No. 3, Aug. 1978-(containing SIGGRAPH '78 proceedings), pp.252-256 _ - . .(published by ACM, P0) Box 12105, Church St. Sta- -tion, New York, NY 10249). _al q m .B E
