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Workstations — present and future trends
Workstations future trends
present and
Howard Rippiner In a recent authoritative report by Frost and Sullivan a 'Workstation' (as used in the Computer Industry) is defined as 'a device which is capable of supporting a recognized programming language'. In other words it could be a high-performance graphics terminal such as a Tektronix 4125, with a CP/M-86 + operating system added, a Digital Equipment Micro VAX II °, an Apollo DN600* or an IBM PC/XT L - to name just a few. What can a workstation do? The 'old' way of doing things in the CAD environment - is by employing a 'dumb' terminal and doing all the calculations and manipulations in the host computer. We can build on this knowledge to see where today's technology stands and where tomorrow's might lead. While it is true to say that computers can aid engineering design via alphanumeric-only terminals, the vast majority of CAD users over the last ten years have used graphics terminals for interaction with the host computer. Very early graphics terminals were built almost entirely around discrete devices - ie separate transistors, diodes, resistors etc, and certainly the packaging density in those days did not allow any form of computing to be undertaken in anything much smaller than a large living room! As component development progressed, discrete components which were used to create 'logic gates' (AND, NAND, OR, NOR) were replaced by integrated circuits. Although these took up much less space than their discrete equivalents, a computer of any worth still occupied a couple of bays of 19 in equipment racking. This meant that unless the user was working directly adjacent to the computer he/she didn't have the benefit of any 'local' processing power. All graphical interaction and amendments were computed in the host computer, which was connected via a relatively slow line (typically 1200 bits/s) to the terminal. The end result was that terminal users wasted a lot of time waiting for the computer to act upon their requests for interaction with, or modification to the picture. They also needed the patience of Job! As logic gates developed and were joined together in one package, the microprocessor was born. This in turn opened up the opportunity to perform various computing tasks within (or alongside) the graphics terminal. The goal was, and still is, to • •
increase the speed of interactivity and picture creation/ amendment reduce the space required by the computer.
The first use of a microprocessor within a terminal was to enable functions to be 'attached' to keys. Nowadays the majority of CAD terminals have dedicated programmable function keys, but early versions redefined keys on the QWERTY keyboard. The next use of microprocessors was Marketing Manager, Information Display Group, Tektronix UK Ltd
CAD International Directory 1986
0408 255 552
to manage the local storage of complete pictures on direct view storage tubes. This means that when a picture needed modifying, only the modifications had to be transmitted to the terminal, rather than the entire picture. This saved significant computing and transmission time. In 1979 Tektronix introduced a range of intelligent graphics terminals - the 4110 series - which they claim has set the standard for the industry in terms of microprocessor-assisted graphics devices. In these products (which use the I ntel 8086 microprocessor and 8087 floating point processor) numerous pictures can be stored simultaneously in the terminal's memory. Pictures can be stored as segments which have a hierarchical structure. This means that logic diagrams for example can be stored as a series of diferent symbols which can be called up in a subroutine fashion by the display list processor. This technique has two major benefits pictures can be stored very efficiently less time is needed to transmit the picture to the terminal and subsequent modifications require minimal host-terminal transmission. The same microprocessors can be used to control locallyconnected peripherals, such as digitizing tablets, printers and plotters. Peripherals controlled in this way impose minimal loading on the host computer. By adding an operating system to the microprocessor such as Digital Research's CP/M-86, the terminal is able to run programs in a high-level language, eg Basic or Fortran, and becomes a workstation in the true sense of the word. Configured in this way, the terminal-based system is ideal for applications such as 2D drafting, graphing, spreadsheeting etc. However, more powerful computing power is needed, for the full gambit of engineering applications, ranging from 2D drafting through to finite element analysis. Today this power can be provided by 32-bit microprocessors such as the National Semiconductor 32016 and 32032 chips which are patterned after Digital Equipment Corporation's VAX Mainframe Technology. The Tektronix 6000 family of UNIX-based Engineering Computer Systems, for example, uses these chip-sets to provide engineering users with a range of powerful workstations. At the lower end, products like the NS32016-based 6130 provide more than sufficient power to provide several concurrent users with sufficient power to perform drafting-related tasks. At the high end the NS32032-based 6210 can handle as many as 25 concurrent users or tasks. Such systems can provide the user computing power well in excess of a Digital Equipment VAX 11/780 ° minicomputer, so the question arises when should one use a workstation and when a mini or mainframe? The dividing line between the two gets less clear daily, especially in an engineering environment.
0010-44851851100017-05$03.00 © 1985 Butterworth & Co (Publishers) Ltd
17
Unlike conventional data-processing tasks, such as payroll or accounts, engineering computing is a very interactive process. Engineering is an evolutionary discipline. This means that each engineer who wishes to use computing power to aid his/her design skills, must have access to fast-response computing power. Large organizations often have engineering computer groups whose job it is to provide a uniform service to many engineers scattered across several buildings and/or sites. These groups are often also charged with ensuring that a central database is maintained, rather than each user having his/her own database. In these situations either a mainframe or large minicomputer to which are connected intelligent (but not programmable) terminals may well be the best answer. However, most companies, large and small, have come to realize that engineers work better in small groups, even though they may need to share a common engineering database with colleagues throughout the company. In these situations the workstation is undoubtedly the right choice for a number of reasons: • • •
•
•
•
Computing power can be purchased as it is required: workstation by workstation. The computing power is placed where it is needed at the engineer's desk, providing maximum interactivity. Different tasks require different amounts of computing power. Using a compatible range of workstations users can choose the right workstation to suit the task in hand. Workstations can be networked together - even between different buildings or sites - so that engineers can share information and a common database. Workstations are designed to work in ordinary offices and do not need the clean-air environment demanded by many mainframe and minicomputer installations. For engineering applications, the cost-per-seat (ie per screen/keyboard) is less for workstation-based installations than it is for the same tasks executed on a mini or mainframe-based installations.
Of course, some workstation networks will incorporate a minicomputer or mainframe. Many companies faced with an over-burdened computer are turning to workstations to alleviate the problem. In these situations, as many tasks as possible are off-loaded to workstations. The central computer is kept for handling computer-intensive programs such as very large finite element analysis and database management tasks. When choosing a workstation there are five important questions you should ask a prospective supplier:
Question 1 What standards does the workstation conform to? Workstations are complex pieces of electronics, and there are several industry standards relevant to their use and operation. Probably the most important of these is the UNIX operating system. Unfortunately the original UNIX written by Berkeley University in the USA has been embellished in different areas by different organizations. The most common (and most advanced) of these is Berkeley 4.2bsd with system V extensions. The Tektronix UTek operating system is an enhanced version of this operating system.
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UN IX was originally designed for software developmem and it is the logical choice for workstation environments for a number of reasons: •
Interactivity o A response is initiated as soon as a command is issued. • Multitasking o Workstation users can initiate new processing tasks without waiting for the current tasks to be completed. • Multiusers o More than one user can be supported simultaneously, which promotes information sharing between workstations within a UN IX-based network. Many users will 'graduate' from a personal computer to a workstation. It is therefore also important that the chosen workstation supports the two most popular operating systems: MS-DOS > and CP/M-86 +. Another important standard to consider is that of Graphics software algorithms. There are two major graphics standards in use today. In Europe the preferred standard is the Graphical Kernel system (GKS) whilst in the USA it is the proposed SIGGRAPH 'Core' standard. Some workstations conform to both standards, giving the user maximum flexibility. As indicated previously, at some stage the user will wish to network stations together. The token ring system used by some manufacturers has two major drawbacks •
The network has to be formed into a complete circle in order to pass the 'token' between all workstations • There is no one standard used by several manufacturers.
On the other hand the IEEE 802 ETHERNET network (which is a collision detect system) does not have to be formed into a complete loop. It is also supported by several major manufacturers including Tektronix and Digital Equipment. While the vast majority of engineering programs are currently written in Fortran, there are several other languages which should be supported by an engineering workstation. Pascal is a structured language for efficient software design; C is a fast efficient language preferred by system programmers and Basic is easy to learn and use, as well as having a large program base. All these languages should be supported by the chosen system.
Question 2 Is the workstation compatible with existing hardware? The vast majority of new users of workstations have already got a terminal connected to a mini, mainframe or timesharing bureau. Quite understandably, they would much prefer to be able to integrate their existing hardware, not only terminals, but minicomputers and printers/plotters as well, into any new workstation they might purchase. Some manufacturer's workstations can only support the same manufacturer's integrated displays and require additional hardware to connect into existing minicomputers. On the other hand, workstations like the Tektronix 6000 family offer a choice of bit-mapped displays or connection of existing equipment via RS-232-C and RS-422 interfacing standards. Since these latter two standards are by far the most common interface standards in use for peripherals, the user's investment in existing hardware is protected.
CAD International Directory 1986
Question 3 What application software is available? Apart from software writers and Original Equipment Manufacturers, purchasers of workstation systems expect to buy 'a solution to a problem', in this case a combination of hardware and applications software. It is therefore important to check what engineering software is available for a particular family of workstations before making a purchase. Some of the packages which should be considered in mechanical, electronic, architectural and civil engineering disciplines are discussed below. The main uses of workstations in mechanical engineering will be for 2D drafting, modelling and finite element analysis. Plot 10 TekniCAD from Tektronix is an example of a 2D drafting package, based on ISO and US standards. It incorporates the concept of free input which means that the user can enter drawing information anywhere on the screen. A background grid is always available to position and size drawing items. Any image can be created using the eight basic item types of lines, points, arcs, notes, dimensions, arrows, symbols and crosshatch. Copy and Modify functions allow the user to move, mirror, matrix, rotate or rescale any individual item, a selected portion of any drawing or an entire drawing. Drawing features can be defined by adding dimensions, notes and crosshatching, and to complete the picture, a parts listing can be created for each drawing. Colour is also available to provide greater detail, to signify a change or to highlight a particular feature. It is often necessary to transfer drawing information between different CAD systems. The recognised way of doing this is to use the IGES format (Initial Graphics Exchange Standard). PATRAN-G by PDA Engineering is an interactive graphics system for the designer analyst. It lets the user create a continuous solid geometric model and then independently produce an analysis model. The engineer can develop multiple analysis models using a single geometric model, allowing optimization of the model for each type of analysis. Extensive construction, viewing and editing features provide a friendly interface for design analysis modelling and the subsequent evaluation of results. Using a powerful geometry-based language, an engineer can define any line, surface or solid as a continuous function. These graphic representations are automatically produced from simple directives. Attributes such as topology, moments-of-inertia, volume and surface areas are defined automatically as the model is constructed and are immediately available. The mathematics built into the program are transparent to the engineer. Complex shapes can be synthesized to produce a mathematical model in a few steps, freeing the engineer to approach problem-solving naturally, logically and spontaneously. There are many benefits to using a package like PATRAN-G. For example it lets the designer evaluate more design alternatives. Loading conditions and material properties can be described as continuous functions to increase environment accuracy. This results in products with a lower probability of defects once produced. Shorter project design cycles are achieved by giving the engineer the tools he/she needs quickly to access design alternatives and interpret products under field loading conditons. This reduces the need for time-consuming construction of prototypes, and increases bottom line profits. The use of colour graphics cuts data results
CAD InternationalDirectory 1986
evaluation time and increases productivity. Information is also provided that helps the designer decided where to add material and how much to add. This results in more efficient designs that use the appropriate amount of material. Like other engineering software, PATRAN-G also handles a wide variety of analysis types. Solids modelling, finite element, finite difference, and results evaluation are all fully supported. The designer does not have to learn multiple systems in order to use all these techniques. The package interfaces to a broad range of engineering analysis programs. This approach to solids modelling lets the designer use accurate numerical intergration techniques uniquely to describe or manipulate every point within the solid. Competitive constructive solid geometry techniques make mesh descriptions of parts practically impossible, while boundary representation techniques lack information on interior points within a solid. PATRAN-G's solids database can be used to satisfy a wide variety of design, analysis and manufacturing requirements. In the area of electronics engineers are using packages like Merlyn-PCB to assist them in the design of complex electronic systems. These packages may offer facilities for the automated design of circuit boards. New designs can be entered interactively through a schematics capture front end, or previously designed schematics can be entered. The schematic information is made available for circuit board packaging through gate assignments to components and components assignments to board locations. Outputs to multiwire and wire-wrap machines can be optionally produced; alternatively, routing patterns can be generated for printed circuit board packaging. Photo plotters for use in printed circuit board manufacture, a variety of final reports, drawings and CAM outputs can be produced. In MERLYNPCB the latter include automatic drill machine interfaces, automatic insertion machine interfaces etc. The package offers users an integrated system which includes substantial computational facilities. Results are computed automatically wherever possible. The essence of the system is the interactive and automatic features, and how those features work together to make designing circuit boards much easier. The relational database is the key feature of Merlyn-PCB. All design information flows in and out of the PCB-BASE> database. Thus, all phasesof design are in proper synchronization. Schematics are captured graphically using a graphic terminal, a four button puck and a tablet. Selections for commands are from on-screen menus, and allow for rapid entry of designs. The user may enter multiple sheets, offsheet references, sheets from another design etc. Verification is a continuous process, and again at every checkpoint. This allows the designer to think more in the line of getting the work done, rather than watching for input errors. Net list generation is accomplished as the design is entered and stored in the database. This eliminates the need for post processing of schematic data. As information and properties are continually added to the design, the NET LIST is always the NET LIST OF RECORD, and the SCHEMATIC is always the SCHEMATIC OF RECORD. Packaging is an automatic feature, once you have completed the schematic entry phase - or the user may choose to package interactively. Placement may be started as soon as the system prompts the user that it has completed packaging. Placement may be perfcrmed by automatic features or by graphic interaction,
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one component at a time. The designer also has the option to place sections of the board by setting up a matrix and letting the system put components in that area only. Routing of the circuit board can be done automatically or interactively, providing the ability to preroute some runs before autoroute, or to clean up, for aesthetics, after routing. Post processing after the board is routed means that the PCB-Base contains all of the information needed to produce documentation, pen-plot output, photo-plot output, drill tapes etc. In all cases, data entry is done once, and the information is then available to all phases of the process. This allows for forward and backward annotation at any phase. The schematic design within Merlyn-PCB produces a visual result that can be plotted as a multi-sheet schematic drawing including automatically generated off-page references, automatically generated electrical net list and, in general, a topologically verified schematic. Entry of circuit board geometric definitions and component parts lists by the user, coupled with automatic access to the electrical net list produced by the schematic, can be used to produce a circuit board placement which, in turn, can be interconnected to produce the information necessary for a manufacturabte board. Schematic information is automatically updated through back annotation; manufacturing requirements are met through automatic production of printed and plotted documentation plus tapes for automated manufacturing. In all cases, the aim is to make data, entered once by the user, available to any and all phases of the system and to have constant checking and correlation for thoroughness and completeness of information at all times. The most important aspect of constant verification of data is the schematic data and the printed circuit board design. With respect to the schematic, the program ensures that the visual results equal the internal electrical database (ega pair of routing lines which cross are considered to be connected in the database only if a connect dot has been located at the crossover point; if no connect dot is present, the lines are not considered to be connected). With respect to the printed circuit board contents, constant clearance checking is done to ensure that the placement and routing results are manufacturable at all times during the design process. The interconnection pattern is computed so that there is continuous correlation to the net list produced with the schematic phase. If a discrepancy should result due to logic changes made during board design, files of information are maintained to ensure that no final output is produced until the discrepancies are resolved. The essential elements of interactive systems have come to be fairly widely understood in recent times. Merlyn-PCB is structured to offer ease of use to the user through human engineering which minimises necessity for eye movement and offers easy to read displays with English language commands for accessing display contents. With respect to data content, dynamic checking for both electrical continuity and mechanical clearances is automatic with entry of each user command ie upon the completion of any interactive data update, the electrical and layout content of the databases are valid. Within the package the user always controls the flow of computation and the production of information. Automatic processes are initiated only by the user and are bounded so that information not intended to be affected by the specified command is left intact. A macro processor
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is available so that users can cause multiple commands to be performed by entry of a single command. Lastly, all user operations are re-entrant; that is, there is no sequence dependency for any command entry (other than where data content is required before a particular command can be executed) during one work session. Work in process can be stored, accessed later in a separate work session, and processing can continue at that later date. Another area of electronic design to benefit from the use of workstations is the design of cable harnesses. The DDS-C package from CADE GmbH is used in Europe by a number of 'blue chip' electronic and mechanical engineering companies. DDS-C is a Drafting Design System for Cabling, and is designed not only to automate the drafting of electrical schematics, but also to totally automate the production of manufacturing documentation. This includes: • • • • • •
stock lists connection lists wire-wrap lists reference lists terminal overview user-defined lists
The package preforms these tasks by using a number of modules. The Schematic Graphic System (SGS) is an advanced user-friendly graphics editor. SGS offers the user a choice of input methods in order to obtain maximum input speed or maximum user-friendliness, or an optimum level of the two. The Component Library System (CLS) provides an hierarchical database management system which forms the basis of all input and output for the DDS-C system. All descriptive data for each component and component assembly is stored in CLS, the minimum description required being the physical, mechanical, electrical and graphical properties of the component. Additional optional descriptions such as pricing information, circuit simulation data etc may also be stored. The package's DRAWING POOL module has the inherent capability of keeping track of all components being used in each design. This feature provides several major advantages: • • • • •
automatic referencing and pinning automatic cross-referencing over an unlimited number of sheets for each drawing set all connections become signal names automatically automatic cross-referencing over more than one set of drawings accurate automation and control of all other manufacturing
As well as the use of workstations by mechanical and electrical engineers, architects and civil engineers have been quick to realise the potential they offer. GABLE (which stands for Graphical Aids for Building Layout and Evaluation) is one such package for architects. GABLE, which was born out of research at Sheffield University, but which is now sold and supported on a commercial basis, is a computer-aided design and drafting system specifically tailored to the needs of the building design professions. The package consists of a series of related modules which can be used separately or together to provide 2D drafting, 3D object modelling and perfor-
CAD International Directory 1986
mance evaluation of buildings and their sites. The Integrated Drafting System (IDS) module enables the rapid development and editing of 2D drawings. However it is frequently quicker to create a 3D model of a building using the Building Modelling System (BMS) than to draw all the plans, elevation and sections directly in IDS. Once a 3D model of a building is created in BMS, 2D projections such as plans, elevations and sections are created automatically. These can then be passed to IDS for further detailing, editing and plotting. BMS provides full, axonometric, isometric and other projections as well as the ability to carry out a wide range of building performance analyses. These include thermal evaluation, daylighting, solar penetration, sound transmittance, condensation risk and quantity surveying. The Object Modelling System (OMS) allows for the 3D geometric modelling of all kinds of objects. These may include furniture and fittings, landscape elements or even whole buildings. These objects may be located in or around buildings created in BMS and can be viewed in all 2D and 3D projections of these buildings. The Ground Modelling System (GMS) which accepts raw land survey data or digitized contours, offers a wide range of survey techniques as well as providing error correction. GMS establishes a full 3D model of the site surface which can then be manipulated in a wide variety of ways. The site surface model can be viewed in all 3D projections and can be used to generate contours and cross sections which can bepassed to the IDS module. Another package in regular use by civil engineers is CADACS from JTC Computer Systems Ltd. CADACS addressed the main disciplines of the construction industry, namely: • • • • • • • •
surveying civil engineering industrial estate development housing mining and mine planning project co-ordination with dimension control architecture general drafting
CAD International Directory 1986
In each case a digital model is developed and integrated with a multi-disciplinary database. Recent research carried out by Tektronix has indicated that a typical engineer spends as much as 60 per cent of his/her time on activities other than the design tasks for which they were trained. These activities include tasks such as project management, spreadsheeting, document and manual preparation, preparation of meeting presentation material etc, as well as the usual array of meetings and personnel management. Software packages to meet these needs are currently being introduced by CAD companies. Finally, what does the future have in store? Certainly, workstation processors are going to provide increasing amounts of calculation power; possibly to such an extent that the 'computer room' becomes a thing of the past. As read/write optical storage replaces magnetic storage, disc units will get smaller and their capacity much higher. Flat-screen solid state displays will replace the cathode ray tube in the next 10 years and voice input will replace the keyboard for many input operations. On the software side, languages will become more natural, ie more like English. Artificial intelligence will be used to create Expert Systems which will greatly assist the engineer with difficult design tasks. If you are currently contemplating the purchase of a CAD system, the last thing you should do is sit on the fence. By all means, take time to investigate what is available, both in hardware and software; then make a purchase. This industry is moving fast and waiting for next year's model will only result in time lost before you and your staff start to gain experience in using a CAD system. What's more, the Company/Organization for whom you work will not benefit from the productivity gains achieved using packages like those mentioned earlier. +Registeredtrade mark of Digital ResearchInc. o Registeredtrade mark of Digital EquipmentCorporation. *Registered trade mark of Apollo Inc. L-Registeredtrade mark of International BusinessMachines. ~Registeredtrade mark of PDA EngineeringLtd. >Registered trade mark of Tektronix Inc.
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present and
Howard Rippiner In a recent authoritative report by Frost and Sullivan a 'Workstation' (as used in the Computer Industry) is defined as 'a device which is capable of supporting a recognized programming language'. In other words it could be a high-performance graphics terminal such as a Tektronix 4125, with a CP/M-86 + operating system added, a Digital Equipment Micro VAX II °, an Apollo DN600* or an IBM PC/XT L - to name just a few. What can a workstation do? The 'old' way of doing things in the CAD environment - is by employing a 'dumb' terminal and doing all the calculations and manipulations in the host computer. We can build on this knowledge to see where today's technology stands and where tomorrow's might lead. While it is true to say that computers can aid engineering design via alphanumeric-only terminals, the vast majority of CAD users over the last ten years have used graphics terminals for interaction with the host computer. Very early graphics terminals were built almost entirely around discrete devices - ie separate transistors, diodes, resistors etc, and certainly the packaging density in those days did not allow any form of computing to be undertaken in anything much smaller than a large living room! As component development progressed, discrete components which were used to create 'logic gates' (AND, NAND, OR, NOR) were replaced by integrated circuits. Although these took up much less space than their discrete equivalents, a computer of any worth still occupied a couple of bays of 19 in equipment racking. This meant that unless the user was working directly adjacent to the computer he/she didn't have the benefit of any 'local' processing power. All graphical interaction and amendments were computed in the host computer, which was connected via a relatively slow line (typically 1200 bits/s) to the terminal. The end result was that terminal users wasted a lot of time waiting for the computer to act upon their requests for interaction with, or modification to the picture. They also needed the patience of Job! As logic gates developed and were joined together in one package, the microprocessor was born. This in turn opened up the opportunity to perform various computing tasks within (or alongside) the graphics terminal. The goal was, and still is, to • •
increase the speed of interactivity and picture creation/ amendment reduce the space required by the computer.
The first use of a microprocessor within a terminal was to enable functions to be 'attached' to keys. Nowadays the majority of CAD terminals have dedicated programmable function keys, but early versions redefined keys on the QWERTY keyboard. The next use of microprocessors was Marketing Manager, Information Display Group, Tektronix UK Ltd
CAD International Directory 1986
0408 255 552
to manage the local storage of complete pictures on direct view storage tubes. This means that when a picture needed modifying, only the modifications had to be transmitted to the terminal, rather than the entire picture. This saved significant computing and transmission time. In 1979 Tektronix introduced a range of intelligent graphics terminals - the 4110 series - which they claim has set the standard for the industry in terms of microprocessor-assisted graphics devices. In these products (which use the I ntel 8086 microprocessor and 8087 floating point processor) numerous pictures can be stored simultaneously in the terminal's memory. Pictures can be stored as segments which have a hierarchical structure. This means that logic diagrams for example can be stored as a series of diferent symbols which can be called up in a subroutine fashion by the display list processor. This technique has two major benefits pictures can be stored very efficiently less time is needed to transmit the picture to the terminal and subsequent modifications require minimal host-terminal transmission. The same microprocessors can be used to control locallyconnected peripherals, such as digitizing tablets, printers and plotters. Peripherals controlled in this way impose minimal loading on the host computer. By adding an operating system to the microprocessor such as Digital Research's CP/M-86, the terminal is able to run programs in a high-level language, eg Basic or Fortran, and becomes a workstation in the true sense of the word. Configured in this way, the terminal-based system is ideal for applications such as 2D drafting, graphing, spreadsheeting etc. However, more powerful computing power is needed, for the full gambit of engineering applications, ranging from 2D drafting through to finite element analysis. Today this power can be provided by 32-bit microprocessors such as the National Semiconductor 32016 and 32032 chips which are patterned after Digital Equipment Corporation's VAX Mainframe Technology. The Tektronix 6000 family of UNIX-based Engineering Computer Systems, for example, uses these chip-sets to provide engineering users with a range of powerful workstations. At the lower end, products like the NS32016-based 6130 provide more than sufficient power to provide several concurrent users with sufficient power to perform drafting-related tasks. At the high end the NS32032-based 6210 can handle as many as 25 concurrent users or tasks. Such systems can provide the user computing power well in excess of a Digital Equipment VAX 11/780 ° minicomputer, so the question arises when should one use a workstation and when a mini or mainframe? The dividing line between the two gets less clear daily, especially in an engineering environment.
0010-44851851100017-05$03.00 © 1985 Butterworth & Co (Publishers) Ltd
17
Unlike conventional data-processing tasks, such as payroll or accounts, engineering computing is a very interactive process. Engineering is an evolutionary discipline. This means that each engineer who wishes to use computing power to aid his/her design skills, must have access to fast-response computing power. Large organizations often have engineering computer groups whose job it is to provide a uniform service to many engineers scattered across several buildings and/or sites. These groups are often also charged with ensuring that a central database is maintained, rather than each user having his/her own database. In these situations either a mainframe or large minicomputer to which are connected intelligent (but not programmable) terminals may well be the best answer. However, most companies, large and small, have come to realize that engineers work better in small groups, even though they may need to share a common engineering database with colleagues throughout the company. In these situations the workstation is undoubtedly the right choice for a number of reasons: • • •
•
•
•
Computing power can be purchased as it is required: workstation by workstation. The computing power is placed where it is needed at the engineer's desk, providing maximum interactivity. Different tasks require different amounts of computing power. Using a compatible range of workstations users can choose the right workstation to suit the task in hand. Workstations can be networked together - even between different buildings or sites - so that engineers can share information and a common database. Workstations are designed to work in ordinary offices and do not need the clean-air environment demanded by many mainframe and minicomputer installations. For engineering applications, the cost-per-seat (ie per screen/keyboard) is less for workstation-based installations than it is for the same tasks executed on a mini or mainframe-based installations.
Of course, some workstation networks will incorporate a minicomputer or mainframe. Many companies faced with an over-burdened computer are turning to workstations to alleviate the problem. In these situations, as many tasks as possible are off-loaded to workstations. The central computer is kept for handling computer-intensive programs such as very large finite element analysis and database management tasks. When choosing a workstation there are five important questions you should ask a prospective supplier:
Question 1 What standards does the workstation conform to? Workstations are complex pieces of electronics, and there are several industry standards relevant to their use and operation. Probably the most important of these is the UNIX operating system. Unfortunately the original UNIX written by Berkeley University in the USA has been embellished in different areas by different organizations. The most common (and most advanced) of these is Berkeley 4.2bsd with system V extensions. The Tektronix UTek operating system is an enhanced version of this operating system.
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UN IX was originally designed for software developmem and it is the logical choice for workstation environments for a number of reasons: •
Interactivity o A response is initiated as soon as a command is issued. • Multitasking o Workstation users can initiate new processing tasks without waiting for the current tasks to be completed. • Multiusers o More than one user can be supported simultaneously, which promotes information sharing between workstations within a UN IX-based network. Many users will 'graduate' from a personal computer to a workstation. It is therefore also important that the chosen workstation supports the two most popular operating systems: MS-DOS > and CP/M-86 +. Another important standard to consider is that of Graphics software algorithms. There are two major graphics standards in use today. In Europe the preferred standard is the Graphical Kernel system (GKS) whilst in the USA it is the proposed SIGGRAPH 'Core' standard. Some workstations conform to both standards, giving the user maximum flexibility. As indicated previously, at some stage the user will wish to network stations together. The token ring system used by some manufacturers has two major drawbacks •
The network has to be formed into a complete circle in order to pass the 'token' between all workstations • There is no one standard used by several manufacturers.
On the other hand the IEEE 802 ETHERNET network (which is a collision detect system) does not have to be formed into a complete loop. It is also supported by several major manufacturers including Tektronix and Digital Equipment. While the vast majority of engineering programs are currently written in Fortran, there are several other languages which should be supported by an engineering workstation. Pascal is a structured language for efficient software design; C is a fast efficient language preferred by system programmers and Basic is easy to learn and use, as well as having a large program base. All these languages should be supported by the chosen system.
Question 2 Is the workstation compatible with existing hardware? The vast majority of new users of workstations have already got a terminal connected to a mini, mainframe or timesharing bureau. Quite understandably, they would much prefer to be able to integrate their existing hardware, not only terminals, but minicomputers and printers/plotters as well, into any new workstation they might purchase. Some manufacturer's workstations can only support the same manufacturer's integrated displays and require additional hardware to connect into existing minicomputers. On the other hand, workstations like the Tektronix 6000 family offer a choice of bit-mapped displays or connection of existing equipment via RS-232-C and RS-422 interfacing standards. Since these latter two standards are by far the most common interface standards in use for peripherals, the user's investment in existing hardware is protected.
CAD International Directory 1986
Question 3 What application software is available? Apart from software writers and Original Equipment Manufacturers, purchasers of workstation systems expect to buy 'a solution to a problem', in this case a combination of hardware and applications software. It is therefore important to check what engineering software is available for a particular family of workstations before making a purchase. Some of the packages which should be considered in mechanical, electronic, architectural and civil engineering disciplines are discussed below. The main uses of workstations in mechanical engineering will be for 2D drafting, modelling and finite element analysis. Plot 10 TekniCAD from Tektronix is an example of a 2D drafting package, based on ISO and US standards. It incorporates the concept of free input which means that the user can enter drawing information anywhere on the screen. A background grid is always available to position and size drawing items. Any image can be created using the eight basic item types of lines, points, arcs, notes, dimensions, arrows, symbols and crosshatch. Copy and Modify functions allow the user to move, mirror, matrix, rotate or rescale any individual item, a selected portion of any drawing or an entire drawing. Drawing features can be defined by adding dimensions, notes and crosshatching, and to complete the picture, a parts listing can be created for each drawing. Colour is also available to provide greater detail, to signify a change or to highlight a particular feature. It is often necessary to transfer drawing information between different CAD systems. The recognised way of doing this is to use the IGES format (Initial Graphics Exchange Standard). PATRAN-G by PDA Engineering is an interactive graphics system for the designer analyst. It lets the user create a continuous solid geometric model and then independently produce an analysis model. The engineer can develop multiple analysis models using a single geometric model, allowing optimization of the model for each type of analysis. Extensive construction, viewing and editing features provide a friendly interface for design analysis modelling and the subsequent evaluation of results. Using a powerful geometry-based language, an engineer can define any line, surface or solid as a continuous function. These graphic representations are automatically produced from simple directives. Attributes such as topology, moments-of-inertia, volume and surface areas are defined automatically as the model is constructed and are immediately available. The mathematics built into the program are transparent to the engineer. Complex shapes can be synthesized to produce a mathematical model in a few steps, freeing the engineer to approach problem-solving naturally, logically and spontaneously. There are many benefits to using a package like PATRAN-G. For example it lets the designer evaluate more design alternatives. Loading conditions and material properties can be described as continuous functions to increase environment accuracy. This results in products with a lower probability of defects once produced. Shorter project design cycles are achieved by giving the engineer the tools he/she needs quickly to access design alternatives and interpret products under field loading conditons. This reduces the need for time-consuming construction of prototypes, and increases bottom line profits. The use of colour graphics cuts data results
CAD InternationalDirectory 1986
evaluation time and increases productivity. Information is also provided that helps the designer decided where to add material and how much to add. This results in more efficient designs that use the appropriate amount of material. Like other engineering software, PATRAN-G also handles a wide variety of analysis types. Solids modelling, finite element, finite difference, and results evaluation are all fully supported. The designer does not have to learn multiple systems in order to use all these techniques. The package interfaces to a broad range of engineering analysis programs. This approach to solids modelling lets the designer use accurate numerical intergration techniques uniquely to describe or manipulate every point within the solid. Competitive constructive solid geometry techniques make mesh descriptions of parts practically impossible, while boundary representation techniques lack information on interior points within a solid. PATRAN-G's solids database can be used to satisfy a wide variety of design, analysis and manufacturing requirements. In the area of electronics engineers are using packages like Merlyn-PCB to assist them in the design of complex electronic systems. These packages may offer facilities for the automated design of circuit boards. New designs can be entered interactively through a schematics capture front end, or previously designed schematics can be entered. The schematic information is made available for circuit board packaging through gate assignments to components and components assignments to board locations. Outputs to multiwire and wire-wrap machines can be optionally produced; alternatively, routing patterns can be generated for printed circuit board packaging. Photo plotters for use in printed circuit board manufacture, a variety of final reports, drawings and CAM outputs can be produced. In MERLYNPCB the latter include automatic drill machine interfaces, automatic insertion machine interfaces etc. The package offers users an integrated system which includes substantial computational facilities. Results are computed automatically wherever possible. The essence of the system is the interactive and automatic features, and how those features work together to make designing circuit boards much easier. The relational database is the key feature of Merlyn-PCB. All design information flows in and out of the PCB-BASE> database. Thus, all phasesof design are in proper synchronization. Schematics are captured graphically using a graphic terminal, a four button puck and a tablet. Selections for commands are from on-screen menus, and allow for rapid entry of designs. The user may enter multiple sheets, offsheet references, sheets from another design etc. Verification is a continuous process, and again at every checkpoint. This allows the designer to think more in the line of getting the work done, rather than watching for input errors. Net list generation is accomplished as the design is entered and stored in the database. This eliminates the need for post processing of schematic data. As information and properties are continually added to the design, the NET LIST is always the NET LIST OF RECORD, and the SCHEMATIC is always the SCHEMATIC OF RECORD. Packaging is an automatic feature, once you have completed the schematic entry phase - or the user may choose to package interactively. Placement may be started as soon as the system prompts the user that it has completed packaging. Placement may be perfcrmed by automatic features or by graphic interaction,
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one component at a time. The designer also has the option to place sections of the board by setting up a matrix and letting the system put components in that area only. Routing of the circuit board can be done automatically or interactively, providing the ability to preroute some runs before autoroute, or to clean up, for aesthetics, after routing. Post processing after the board is routed means that the PCB-Base contains all of the information needed to produce documentation, pen-plot output, photo-plot output, drill tapes etc. In all cases, data entry is done once, and the information is then available to all phases of the process. This allows for forward and backward annotation at any phase. The schematic design within Merlyn-PCB produces a visual result that can be plotted as a multi-sheet schematic drawing including automatically generated off-page references, automatically generated electrical net list and, in general, a topologically verified schematic. Entry of circuit board geometric definitions and component parts lists by the user, coupled with automatic access to the electrical net list produced by the schematic, can be used to produce a circuit board placement which, in turn, can be interconnected to produce the information necessary for a manufacturabte board. Schematic information is automatically updated through back annotation; manufacturing requirements are met through automatic production of printed and plotted documentation plus tapes for automated manufacturing. In all cases, the aim is to make data, entered once by the user, available to any and all phases of the system and to have constant checking and correlation for thoroughness and completeness of information at all times. The most important aspect of constant verification of data is the schematic data and the printed circuit board design. With respect to the schematic, the program ensures that the visual results equal the internal electrical database (ega pair of routing lines which cross are considered to be connected in the database only if a connect dot has been located at the crossover point; if no connect dot is present, the lines are not considered to be connected). With respect to the printed circuit board contents, constant clearance checking is done to ensure that the placement and routing results are manufacturable at all times during the design process. The interconnection pattern is computed so that there is continuous correlation to the net list produced with the schematic phase. If a discrepancy should result due to logic changes made during board design, files of information are maintained to ensure that no final output is produced until the discrepancies are resolved. The essential elements of interactive systems have come to be fairly widely understood in recent times. Merlyn-PCB is structured to offer ease of use to the user through human engineering which minimises necessity for eye movement and offers easy to read displays with English language commands for accessing display contents. With respect to data content, dynamic checking for both electrical continuity and mechanical clearances is automatic with entry of each user command ie upon the completion of any interactive data update, the electrical and layout content of the databases are valid. Within the package the user always controls the flow of computation and the production of information. Automatic processes are initiated only by the user and are bounded so that information not intended to be affected by the specified command is left intact. A macro processor
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is available so that users can cause multiple commands to be performed by entry of a single command. Lastly, all user operations are re-entrant; that is, there is no sequence dependency for any command entry (other than where data content is required before a particular command can be executed) during one work session. Work in process can be stored, accessed later in a separate work session, and processing can continue at that later date. Another area of electronic design to benefit from the use of workstations is the design of cable harnesses. The DDS-C package from CADE GmbH is used in Europe by a number of 'blue chip' electronic and mechanical engineering companies. DDS-C is a Drafting Design System for Cabling, and is designed not only to automate the drafting of electrical schematics, but also to totally automate the production of manufacturing documentation. This includes: • • • • • •
stock lists connection lists wire-wrap lists reference lists terminal overview user-defined lists
The package preforms these tasks by using a number of modules. The Schematic Graphic System (SGS) is an advanced user-friendly graphics editor. SGS offers the user a choice of input methods in order to obtain maximum input speed or maximum user-friendliness, or an optimum level of the two. The Component Library System (CLS) provides an hierarchical database management system which forms the basis of all input and output for the DDS-C system. All descriptive data for each component and component assembly is stored in CLS, the minimum description required being the physical, mechanical, electrical and graphical properties of the component. Additional optional descriptions such as pricing information, circuit simulation data etc may also be stored. The package's DRAWING POOL module has the inherent capability of keeping track of all components being used in each design. This feature provides several major advantages: • • • • •
automatic referencing and pinning automatic cross-referencing over an unlimited number of sheets for each drawing set all connections become signal names automatically automatic cross-referencing over more than one set of drawings accurate automation and control of all other manufacturing
As well as the use of workstations by mechanical and electrical engineers, architects and civil engineers have been quick to realise the potential they offer. GABLE (which stands for Graphical Aids for Building Layout and Evaluation) is one such package for architects. GABLE, which was born out of research at Sheffield University, but which is now sold and supported on a commercial basis, is a computer-aided design and drafting system specifically tailored to the needs of the building design professions. The package consists of a series of related modules which can be used separately or together to provide 2D drafting, 3D object modelling and perfor-
CAD International Directory 1986
mance evaluation of buildings and their sites. The Integrated Drafting System (IDS) module enables the rapid development and editing of 2D drawings. However it is frequently quicker to create a 3D model of a building using the Building Modelling System (BMS) than to draw all the plans, elevation and sections directly in IDS. Once a 3D model of a building is created in BMS, 2D projections such as plans, elevations and sections are created automatically. These can then be passed to IDS for further detailing, editing and plotting. BMS provides full, axonometric, isometric and other projections as well as the ability to carry out a wide range of building performance analyses. These include thermal evaluation, daylighting, solar penetration, sound transmittance, condensation risk and quantity surveying. The Object Modelling System (OMS) allows for the 3D geometric modelling of all kinds of objects. These may include furniture and fittings, landscape elements or even whole buildings. These objects may be located in or around buildings created in BMS and can be viewed in all 2D and 3D projections of these buildings. The Ground Modelling System (GMS) which accepts raw land survey data or digitized contours, offers a wide range of survey techniques as well as providing error correction. GMS establishes a full 3D model of the site surface which can then be manipulated in a wide variety of ways. The site surface model can be viewed in all 3D projections and can be used to generate contours and cross sections which can bepassed to the IDS module. Another package in regular use by civil engineers is CADACS from JTC Computer Systems Ltd. CADACS addressed the main disciplines of the construction industry, namely: • • • • • • • •
surveying civil engineering industrial estate development housing mining and mine planning project co-ordination with dimension control architecture general drafting
CAD International Directory 1986
In each case a digital model is developed and integrated with a multi-disciplinary database. Recent research carried out by Tektronix has indicated that a typical engineer spends as much as 60 per cent of his/her time on activities other than the design tasks for which they were trained. These activities include tasks such as project management, spreadsheeting, document and manual preparation, preparation of meeting presentation material etc, as well as the usual array of meetings and personnel management. Software packages to meet these needs are currently being introduced by CAD companies. Finally, what does the future have in store? Certainly, workstation processors are going to provide increasing amounts of calculation power; possibly to such an extent that the 'computer room' becomes a thing of the past. As read/write optical storage replaces magnetic storage, disc units will get smaller and their capacity much higher. Flat-screen solid state displays will replace the cathode ray tube in the next 10 years and voice input will replace the keyboard for many input operations. On the software side, languages will become more natural, ie more like English. Artificial intelligence will be used to create Expert Systems which will greatly assist the engineer with difficult design tasks. If you are currently contemplating the purchase of a CAD system, the last thing you should do is sit on the fence. By all means, take time to investigate what is available, both in hardware and software; then make a purchase. This industry is moving fast and waiting for next year's model will only result in time lost before you and your staff start to gain experience in using a CAD system. What's more, the Company/Organization for whom you work will not benefit from the productivity gains achieved using packages like those mentioned earlier. +Registeredtrade mark of Digital ResearchInc. o Registeredtrade mark of Digital EquipmentCorporation. *Registered trade mark of Apollo Inc. L-Registeredtrade mark of International BusinessMachines. ~Registeredtrade mark of PDA EngineeringLtd. >Registered trade mark of Tektronix Inc.
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