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HEW LET"TPACKARD CD ei APRIL 19B5 © Copr. 1949-1998 Hewlett-Packard Co. HEW LETT-PACKARD UlÕs)LJ-Ú April 1985 Volume 36 • Number 4 Articles 4 A Low-Cost, Compact, Block-Mode Computer Terminal, by Jean-Louis Chapuis and Michèle in Reliability and ergonomic considerations were given high priority in its design. 7 A Reliable, Low-Cost Keyboard Interface Mechanical Design of a Low-Cost Terminal, by Michel Cauzid Integral display tilt 8 and swivel mechanisms anda detached low-profile keyboard help it adapt to users' needs. 9 VLSI Design in the HP 2392A Terminal, by Jean-Jacques Simon The cost of the CRT control function was reduced 80% by integrating it in a single VLSI chip. 13 A Fast Gate Array Companion for a CRT Controller 15 How to Scroll Smoothly 1O Fully Automated Production of Display Terminal Printed Circuit Assemblies, by D Christian-Marcel Dulphy DIP and axial inserters install 103 components and a six-axis robot inserts 41 more. 1O A Low-Cost, Reliable Analog Video Display Terminal Design, by Rene Martinelli and O Jean Yves Chatron A small cabinet with no fan made heat dissipation a major concern. 23 Authors An Intelligent Plotter for High-Throughput, Unattended Operation, by Martin L Stone, Peter L transparency JefferyW. Groenke, andTodd L Russell A cut-sheet paper or transparency feeder graphics 6g pen acceleration enable users to get multiple copies of presentation graphics quickly and easily. Low-Mass, Low-Cost Pen-Lift Mechanism for High-Speed Plotting, by Tammy V. Herr and Hatem E. Mostafa An adaptive pen up/down cycle reduces pen nib wear without sacrificing plotting speed. O A The HP 7550A X-Y Servo: State-of-the-Art Performance on a Budget, by David C. O I Tribolet, Kenneth A. Regas, and Thomas J. Halpenny A 32-bit microprocessor closes three feedback. loops in this plotter using position and velocity feedback. r^A Firmware Provides Simple and Powerful Plotter Operation, by Thomas J. Halpenny OH" Polygon area fill, downloadable character sets, and replot and vector buffers are some of the key enhancements. Editor, Richard Susan Doian • Associate Editor, Kenneth A. Shaw • Assistant Editor. Nancy R Teater • Art Director, Photographer, An/id A. Danielson • Support Supervisor, Susan E.Wright Illustrator, Publisher, S. Vanderbloom, • Administrative Services, Typography, Anne S. LoPresti • European Production Supervisor, Michael Zandwijken • Publisher, Russell M. H Berg C Hewlett-Packard Company 1985 Printed in U.S.A. 2 HEWLETT-PACKARD JOURNAL APRIL 1985 © Copr. 1949-1998 Hewlett-Packard Co. In this Issue The video display terminal, or VDT, is the latest addition to the typical office as battery of standard equipment, joining such old standbys as the in fre the desk calendar, and the telephone. With increasing fre quency, however, the "VDT" on an individual's desk is likely to be a personal computer rather than a simple terminal driven by a host computer. A PC can act a a terminal if its owner so chooses, but it can also operate as a stand-alone computer with local intelligence and mass storage capability. In the future, the PC may replace the VDT as their costs become comparable, but today there are still plenty of applications for the simple VDT, provided that has cost, several important user requirements. First, it has to be low in cost, because the cost of terminals is an increasing proportion of the cost of an office-automation computer system. Second, it has to be ergonomically designed, because we've learned that people develop physical problems when they have to adapt to their work areas rather than the other way around. Third, a VDT has reliable, be compact and quiet to fit into the office environment. Fourth, it has to be reliable, and finally, it has to work with the customer's computer system. In the articles on pages 4 to 22, the designers of the HP 2392A Display Terminal tell us how they addressed these requirements in the design and manufacture of their product. To lower costs, for example, the HP 2392A printed circuit illustrates production facility in Grenoble is almost completely automated. Our cover illustrates the terminal's ergonomic design, which includes tilt and swivel mechanisms, a choice of display colors, and the same low-profile keyboard that's used on HP PCs and other computer equipment. Need fifty multicolor overhead transparency for a presentation and fifty copies of it, also in color, to hand this to those attending? The HP 7550A Graphics Plotter is designed for this kind of job. Under the direction of a user's graphics program running on a host computer, the HP 7550A can make multiple copies of an eight-color original graph automatically. The plotter automatically loads sheets loaded hand) and transparency material (film and vellum material have to be loaded by hand) and races through the paper plots wth 6g acceleration and up to 80-centimeter-per-second pen speed. These and other advanced features of this intelligent plotter are described by its designers in the articles on pages 25 to 36. -R. P. Do/an What's Ahead The deceptively simple concept of ejecting minute ink droplets to form high-quality text by momentarily boiling the ink in the nozzle cavity is the subject of next month's issue. The develop ment of this technology and the first HP product to use it, the ThinkJet printer, will be described. APRIL 1985 HEWLETT-PACKARD JOURNAL 3 © Copr. 1949-1998 Hewlett-Packard Co. A Low-Cost, Compact, Block-Mode Computer Terminal The design emphasizes ergonomics and very high reliability as well as low cost and compactness. by Jean-Louis Chapuis and Michèle Prieur IN 1981, HEWLETT-PACKARD introduced the HP Circuits Operation (see article, page 9). The other is an 2622A Terminal, which was the basic product of the HP ECL gate array developed with an outside vendor. As a 262X family. At that time, the low-cost terminals war result, the HP 2392A (Fig. 1) has one fourth as many chips had already started, and many of HP's competitors were on its logic board as its predecessor (see Fig. 2), yet offers offering new character- and block-mode terminals at very greatly improved performance and features. aggressive prices. A market study showed that more and Even the power supply of this new terminal was an in- more customers were becoming sensitive to the cost of their house design. This was because no commercially available video display units, because they represent a significant power unit could match the stringent requirements for re part of the total cost of a computer system. liability, compactness, and price. In response, the HP 2392A Terminal project was started Ergonomics requirements dictated a tilt and swivel capa at HP's Grenoble Personal Computer Division. The project bility. The traditional method of providing the tilt feature had very ambitious objectives: has been an articulated pedestal that tilts the entire unit. • Cut the manufacturing cost of the previous terminal in This method adds substantial height to the terminal and half increases its shipping bulk. The solution was to hinge the • Develop a new package design emphasizing ergonomics CRT tube and tilt the tube itself with respect to the terminal and compactness housing. The external dimension constraints imposed by • Achieve a reliability equivalent to less than a single fail HP's corporate design standardization program (width of ure every ten years. 325 mm) and the internal space required by the tilting tube It was realized early in the project that only the use of left little room for electronics. Various attempts at the lay specialized VLSI components would drastically reduce the out and arrangement of the power supply and sweep component costs and allow the price and reliability objec printed circuit boards were made to facilitate heat dissipa tives to be met. Two VLSI chips were designed. One is a tion and avoid a cooling fan, which is highly undesirable CRT controller manufactured at HP's Cupertino Integrated in the office environment. A very close relationship with HP's U.S. divisions was required to ensure a good integration of the terminal with HP computers, software, and printers. On the other hand, close collaboration was necessary with European countries to localize the product. Fig. 2. The HP 2392A's logic board (right) has only one fourth Fig. 1. HP 2392A Terminal. as many chips as earlier HP designs (left). 4 HEWLETT-PACKARD JOURNAL APRIL 1985 © Copr. 1949-1998 Hewlett-Packard Co. Feature Set and Firmware Design means that characters to be displayed are stored in memory Compatibility with existing HP block-mode terminals blocks taken from a linked list of free blocks. The video was of paramount importance for the HP 2392 A. Therefore, structure is composed of linked row headers, which point the HP 2392A firmware is a superset of the firmware of its to data blocks that contain the row data. predecessor, the HP 2622A. Additional features include One normal row is composed of a 16-byte header and smooth scrolling, a parallel or serial printer port, dynamic from one to four 80-byte data blocks. allocation of display memory, secret video enhancement, When a line is empty, only a header of 16 bytes is used. and datacom speeds up to 19,200 baud. Whenever one character is entered in this row, an 80-byte The HP 2392A can display softkey labels and error mes block is fetched from the pool of free blocks and is allocated sages in ten languages and can handle 17 national to this header.

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