Digital Technical Journal, Volume 3, Number 4: Image Processing
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Image Processing, Video Terminals, and Printer Techuologies Digital Technical Journal Digital Equipment Corporation Volume 3 Number 4 Fall 1991 Editorial Jane C. Blake, Editor Helen L. Patterson, Associate Editor Kathleen M. Stetson, Associate Editor Leon Descoteaux, Associate Editor Circulation Catherine M. Phillips, Administrator Sherry L. Gonzalez Production Mildred R. Rosenzweig, Production Editor Margaret L. Burdine, Typographer Peter R. Woodbury, Illustrator Advisory Board Samuel H. Fuller, Chairman Richard W Beane Robert M. Glorioso Richard]. Hollingsworth John W McCredie Alan G. Nemeth Mahendra R. Patel F Grant Saviers Victor A. Vyssotsky Gayn B. Winters The Digital Technicaljournal is pub I ished quarterly by Digital Equipment Corporation, 146 Main Street ML01-3/B68, Maynard, Massachusetts 01754-2571. Subscriptions to the journal are $40.00 for four issues and must be prepaid in U.S. funds. University and college professors and Ph.D. students in the electrical engineering and computer science fields receive complimentary subscriptions upon request. Orders, inquiries, and address changes should be sent to the Digital Technicaljournal at the published-by address. Inquiries can also be sent electronically to DTJ@CRLDECCOM. Single copies and back issues are available for $16.00 each from Digital Press of Digital Equipment Corporation, 1 Burlington 0 80 -45 Woods Drive, Burlington, MA 1 3 39. Digital employees may send subscription orders on the ENET to RDVAX::)OURNAL or by interoffice mail to mailstop MLOI-3/B68. Orders should include badge number, site location code, and address. All employees must advise of changes of address. Comments on the content of any paper are welcomed and may be sent to the editor at the published-by or network address. Copyright© 1991 Digital Equipment Corporation. Copying without fee is permitted provided that such copies are made for use in educational institutions by faculty members and are not distributed for commercial advantage. Abstracting with credit of Digital Equipment Corporation's authorship is permitted. All rights reserved. The information in the journal is subject to change without notice and should nor be construed as a commitment by Digital Equipment Corporation. Digital Equipmem Corporation assumes no responsibility for any errors that may appear in thejournal. lSSN 0898-901X Documentation Number EY-H889E-DP The following are trademarks of Digital Equipment Corporation: ALL-IN-1, DECimage, DECnet, DECprint, DECserver, DECstarion, DECwindows, Digital, the Digital logo, LAT, LN03, MicroVAX, PrintServer, Q-bus, ReGIS, rtVAX, ULTRIX, VA,'\, VAXELN, VAXstation, VMS, VT1000, VTI200, VT1300, and VXT 2000. Apple DeskTop Bus is a trademark and LocalTal k is a registered trademark of Apple Com purer, Inc. Motorola and 68000 are registered trademarks of Motorola, Inc. Open Software Foundation is a trademark and OSF and OSF/1 are CoverDesign registered trademarks of Open Software Foundation, Inc. High-performance screen display of bitonal images is one PostScript is a registered trademark of Adobe Systems, Inc. of the topics in this issue. The handwriting and manually Texas Instruments is a trademark of Texas Instruments, Inc. produced technical drawings on our cover are types of images UNIX is a registered trademark of UNIXSystem Laboratories, Inc. that can be scanned, st01·ed electronically, ana then displayed X Window System is a trademar.k of the Massachusetts Institute on an X terminal screen; portions of an image can be enlarged of Technology. or rotated on screen. Book production was done by Digital's Database Publishing Group The cover was designed trySandra Calef of Calef Associates. in Northboro, MA. I Contents 7 Foreword Larry Cabrinety Image Processing, Video Terminals, and Printer Technologies 9 Hardware Accelerators for Bitonal Imag e Processing Christopher ). Payson, Christopher ]. Cianciolo, Robert N. Crouse, and Catherine F. Winsor 26 X Window Terminals Bjorn Engberg and Thomas Porcher 36 ACCESS. bus, an Open Desktop Bus Peter A. Sichel 43 Design of the DECprint Comm on Printer Supervisor for VMS Systems Richard Landau and Alan Guenther 55 The Comm on Printer Access Protocol James D. Jones, A jay P Kachrani, and Thomas E. Powers 61 Design of the Turbo PrintServer 20 Controller Guido Simone, Jeffrey A. Metzger, and Gary Va illette 1 I Editor's Introduction boards, mice, and tablets, all of which may not be made by the same company. A new open desktop bus, described by Peter Sichel, is a simple means to connect as many as 14 low-speed devices to a desk top system. In his paper, Peter presents the project background, reviews the I'C technology on which the bus is based, and describes the protocol and the configuration process. Hard-copy presentation of data and recent devel opments in printer tec hnologies are the topics of the next three papers. Rick Landau and Alan Guenther review the DECprint Printing Services, which is jane C. Blake software that controls numerous printer fe atures Editor for a wide range of printers. Also called a common print symbiont, this component of the VMS print Products designed for quality, high-performance ing system supports several page description lan presentation of data in both video and hard-copy guages, handles multiple media simultaneously, form are the topics of papers in this issue of the and uses different I/0 interconnections and com Digital Te chnical jo urnal. The design challenges nmnication protocols. range from managing the huge storage require Both DECprint Printing Services and the subject ments of images for display on X terminals to ensur of the next paper, the common printer access pro ing high-performance in a feature-rich printer tocol, are part of the DECprint architecture. The environment. CPAP provides the fundamental services necessary Image processing is the subject of the opening for the presentation of data at the printer. Jim paper by Chris Payson, Chris Cianciolo, Bob Crouse, Jones, Ajay Kachrani, and To m Powers describe the and Cathy Winsor. The authors note that one advan challenges of developing a protocol that operates tage of scanning images for screen display is the in a he terogeneous, internetworking environment input time saved; however, the scanned images and that also ensures backward compatibility with and data can consume significant amounts of stor older products. Their success in developing a high age space. They then review the development of an performance protocol is evidenced by OSF accep image accelerator board that not only helps solve tance of CPAP for inclusion in a future release of the problem of storage but also addresses the need OSF/1. for high-performance display-view and manipula As was the case with the CPAP, performance tion-of bitonal images. In addition to specifics of was also key in the development of the turbo the board implementation, the authors offe r an PrintServer 20 controller. Guido Simone ,Jeff Me tzger, overview of imaging concepts, terms, and future and Gary Vaillette explain that the req uirements of directions for image accelerators. complex documents demanded turbo controller The terminal on which the image accelerator performance that was five to eighttimes that of the board resides is DECimage 1200, an X terminal. current controller. To aiel them in making design X terminals development in general, including a decisions, a performance analysis tool, RETrACE, discussion of the VT1200, is the subject of a paper was created and is described here. Authors also by Bjorn Engberg and To m Porcher. Bjorn and To m relate how they us ed existing chips in order to keep fo cus their discussion on a comparison of the development costs low and still deliver a high X terminal and X workstation environments, and perfo rmance controller. explain why X terminals are a low-cost alternative. The editors thank Liz Griego-Powell of the Video, The authors present the design choices debated by Image and Print Systems Gro up for her he lp in the engineers during the development of Digital's preparing this issue. X terminals, including the selection of a hardware platform, terminal and window management, X server, com munications protocols, and fo nt file systems. Video terminal and workstation users need the assistance of a number of 1/0 devices, such as key- 2 Biographies I Christopher J. Cianciolo As a hardware design engineer in the Video, Image and Print Systems Group, Chris Cianciolo is currently working on the design for the group's latest imaging product. Chris jo ined Digital in 1985 after par ticipating in a co-op session in the Power Supply Engineering Group. He also participated in co-op sessions for Charles Stark Draper La boratory, Inc. on a fib er-optic missile guidance system project. He received his B.S.E.E. from No rtheastern University in 1988 and is currently pursuing an M.S.E.E., also from Northeastern. Robert N. Crouse Senior engineer Bob Crouse is a member of the Video, Image and Print Systems Group. He is currently working on the advanced devel opment of new imaging technology for X window terminals. Bo b was project engineer for the development of a bitonal imaging accelerator for a low-end VAXstation workstation. As a member of the Electronic Storage Development Group , he designed a double-bit error detection and correction circuit fo r a VAX mainframe. Bob received his B.S.E.E. from NortheasternUniversity and holds one patent. Bjorn Engberg As a principal software engineer in the Video, Image and Print Systems Group, Bj orn Engberg was the main architect and software project leader for the VTIOOO and VT1200 X window terminals. He joined Digital in 1978 and worked as a development engineer at CSS in Sweden, where he modified Digital's terminals for the European market. He relocated to the United States in 1982 to work on the VT240, the VT320, the LJ250, and several advanced devel opment projects.