Cadam Drafting
Cecile Lilien
This is probably the most complicated chapter in this book in that it involves a number of different companies involved in an overlapping manner over several decades with multiple different products. It does not follow a strictly chronological format very well. Therefore, I have chosen to cover some of the following subjects over longer timeframes rather the chop them up into time-dependent chunks. Also, this is really the story of CADAM and CATIA and not of IBM per se. As a consequence, I have kept the discussion of IBM to the minimum required to put what occurred with these software products into context. Finally, although Dassault Systmes acquired SolidWorks in 1997, that company and its products are discussed separately in Chapter 18.
One of the first engineers assigned to Project Design was R. Lee Whitney who joined Lockheed-California as an associate engineer in late1965 after a brief stint at Boeing. He went to work for Boeing after receiving a BS in mathematics from Portland State University. He later added an MS in computer science and an MBA while at Lockheed. Whitney represents the most complete repository of information regarding CADAM in that he was associated with this product and MICRO CADAM for over 30 years.
The mainframe implementation of what eventually became CADAM was forced to live with a number of limitations imposed by the hardware and the time-sharing mode of operation. The latter factor dictated that models had to be kept small, otherwise one or two users working with large models could slow the system down for all the other users.
Early IBM graphics terminals such as the 2250 had only 8KB of refresh memory, limiting how much graphics could be displayed at one time. There were also problems with the floating point format IBM was using in the mid-1960s. It was less precise than the alternate IEEE standard and truncated results rather than rounding. Whitney describes a test in which he rotated a 100-inch line 180 degrees in one degree increments. At the end of the test, the line was just 97-inches long.[1] As a result, careful attention was subsequently paid to avoiding numerical accuracy problems.
Bradley died in 1968 in a mountain climbing accident and was replaced by Jean Lucas. One technical change that resulted was increased use of APT for NC work. Bradley had not been a fan of APT while Lucas favored using it. Even though CADAM was not a three-dimensional system in the classical sense, it did have strong NC capabilities. Fundamentally, the software used a two-and-a-half dimensional technique not unlike the descriptive geometry techniques used by traditional drafters.
The software facilitated the creation of multiple views of an object without the need to use temporary construction lines. Using this methodology, it was possible for a user to design elements such as a pocket with sloping sides and then program a five-axis milling machine to cut the sides of this pocket using an approach called swarf cutting.
From the initial 360/50, the CADAM group were provided with increasingly powerful hardware. In late 1968, the system which was used for both software development and actual engineering design was upgraded to an IBM 360/91, one of the most powerful computers IBM had built up until that time. It had a 2MB memory (less memory than what is required today for a high resolution digital photograph.) and was capable of two MIPS performance. The computer had drum, disk and tape memory and fairly soon was supporting 12 display terminals. CADAM used 128 KB partitions to support each terminal and frequently, the system was running several different engineering applications simultaneously.
Eight of these terminals were located 4,500 feet away from the computer center in the engineering department. This was done using a high-speed data link provided by IBM that incorporated cables placed in a helium-filled conduit. According to Whitney, performance of the remote terminals was comparable to those located adjacent to the computer.3
Engineering was against this move in that it felt that the software provided them a competitive advantage. They were overruled and in 1972 Lockheed set up a separate organization to continue the development and marketing of the software. This was also the point in time when the software was formally named CADAM.
The first three installations outside of Lockheed California in 1974 were IBM Paris (to facilitate selling CADAM in Europe), Lockheed Missile and Space Corporation in Sunnyvale, California and Lockheed Georgia. This was followed the next year by sales to Northrop, Grumman and Dassault Aviation (Avions Marcel Dassault). Unlike most commercial CAD system vendors, Lockheed provided source code to its customers enabling them to make changes to the software.
Lockheed Georgia utilized a four-terminal system on a project to produce a stretched C141 aircraft for the Air Force. The original plan envisioned a maximum staff of nearly 70 people working on the project for a period of 18 months. They were able to do the work with a staff of 40 and they did it in 12 months.
CADAM was an expensive solution and many engineering managers were reluctant to make the investment in the mid-1970s. Gradually, the salaries of engineers increased and the cost of the computer hardware per user came down significantly. By 1976 the economics looked much better and usage took off. At Lockheed California, the number of CADAM terminals in use went from about 40 in 1976 to over 220 in 1980.
IBM fairly quickly realized that CADAM could help it sell lots of large mainframe computers as well as numerous graphics terminals. In 1978 IBM signed a non-exclusive marketing agreement with Lockheed and set up a sales and support staff to promote CADAM running on IBM computer systems. Lockheed also signed similar agreements with Fujitsu in Japan and Perkin-Elmer, a manufacturer of 32-bit minicomputers. The Fujitsu relationship resulted in a meaningful volume of business, particularly in Japan, but the Perkin-Elmer deal never really got off the ground. In 1982, Lockheed established CADAM, Inc. as a separate company to continue the development and marketing of CADAM.
Several CADAM features characterized the early versions of the software. First and foremost, the software was developed to run on IBM mainframe computers using vector refreshed display terminals. At the time, these terminals had very little local computing capability so most graphic manipulations were done by the host computer itself. Since there was little incentive to make the software machine-independent, only about 75 percent of the code was written in FORTRAN. The balance was done in assembly language which resulted in very fast graphic manipulations. This was one way the Lockheed programmers were able to meet the 0.5 second reaction speed mentioned earlier.
At the time CADAM was being developed, most other CAD systems used Tektronix storage tube graphics displays. While they could display a considerable amount of fine resolution data, images could not be selectively erased. The storage tube had very limited capability to display menu-type information. The IBM and compatible vector refresh displays were more expensive than the storage tube devices but could be selectively erased and images could be moved around. They also could rapidly change lists of menu items. The downside was that they could display a limited amount of data before they became overloaded and started to flicker.
IBM and Lockheed were adamant that, overall, the vector refresh devices were preferred over storage tube displays. The selection of displayed entities was very quick because these terminals used a light-pen as the operator input device. With a light-pen the user could directly select entities rather than requiring the computer to indirectly match a coordinate input from a tablet device to the drawing database. CADAM complemented the light-pen with a 32-button programmable function box. Most CADAM users became proficient in using the combination of keyboard, function box, light-pen and on-screen menus to initiate graphic actions.
CADAM was fundamentally a two-and-a-half-dimension system that enabled drafters to create multiple views of complex objects using traditional manual drafting techniques. This enabled users to quickly prepare isometric drawings from these orthographic views. In addition to production drafting, the software was used to automate NC machine tool programming. CADAM could also be used to compute twodimensional section properties.
By 1982, Lockheed began shipping a version of CADAM with three-dimensional capabilities. To produce drawings from the model the user created a two-dimensional projection and then manually added dimensions and notes. The software handled a variety of surface types and could be used to create finite element models although the latter task involved a substantial amount of manual intervention. Automatic meshing was off in the future. Lockheed provided several support modules including a Data Management Module for cataloging data files, a Statistical Data and Report Generator that provided system managers with detailed operating statistics such as system response times, an Accounting Information Modules for recording man-hours spent on specific projects and a Geometry Interface Module that provided an interface to the CADAM database for user developed software.
Hardware prices in the 1982 era ranged from about $265,000 for an IBM 4331 Group II computer with two 3251 displays to several million for an IBM 3081 with perhaps 20 or more terminals. A basic CADAM configuration with drafting, data management and hard copy output cost $26,350 plus a monthly fee of $3,200 irrespective of the size of the IBM mainframe it was being run on. As a consequence, adding additional seats only cost the user the price of the display terminal.
As mentioned earlier, IBM obviously was interested in CADAM because it had the potential to help the company sell a large number of expensive mainframe computers and many thousands of 3250 and 5080 graphics terminals. The earlier chart shows the sale of the mainframe version of CADAM over the years.
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