Applicon CAD/CAM

In the first half of the 1980's, I designed printed circuit boards on a Applicon AGS/895 CAD system for CADgineering Services, and a Applicon Series 4000 system for Potter & Brumfield.

The Applicon systems consisted of a Digital Equipment Corp PDP-11/34 computer with four color graphics terminals. Each system had a Calcomp pen plotter, and CADgineering had a digitizing table to enter hand-drawn designs. System management was on VT100 Terminals, using the RSX-11M operating system.

The Applicon systems featured a dual-processor architecture: the DEC PDP-11/34 with 216K main memory and a proprietary 32-bit graphics processor called Graphics 32, with 224K memory. The Graphics 32 processor handled many of the viewing functions such as windowing and clipping. For storage, an 80MB hard drive was provided.

For 2D printed circuit board design, Applicon AGS/870 software was used. For 3D mechanical design, Applicon AGS/880 software was used. Potter & Brumfield also had a VAX-11/751 running Applicon's 3D system called BRAVO for mechanical and solids modeling.

Each Applicon workstation had a 19-inch display with a resolution of 768 x 576 and 8 colors (including black).

Inputs to the system included a graphics tablet with stylus (aka pen) with a switch that was activated when you pressed down, a keyboard and a push-button command tablet.

The Applicon system featured the unique ability to allow designers to "draw " commands with various pen-strokes, called Tablet Symbol Recognition (TSR). Users could define pen-strokes in a "teach" mode to execute virtually any command. For example, drawing a "D" would enter the delete component (DELC) command, deleting anything that was previously selected. Macros could be created, such that multiple commands could be executed based on a single input. For example, the delete command pen-stroke could include an "execute undraw" (XEQU) command to remove from the screen the elements being deleted. For another example, if the user wanted to zoom in on an area, they could draw a triangle around the area to zoom (or roughly a circle, starting at the top and going counter clockwise back to the top). But, before the system zoomed, the macro could save the current view, making it easy to return to it after working in the zoomed area.  Or, draw a "C" to center the window where the "C" was drawn. A "Z" would fit the entire drawing on the screen. Pen-strokes would easily add lines, arcs and cells. Strokes could also include "dotting" or pressing on the pen button. Examples include add line or add vertex. TSR made drawing on the Applicon system very fast and easy. Commands could also be typed, entered from the tablet by pushing on a "soft" menu item or programmed into the push-button button command tablet. Buffering several commands was also useful before executing all of them.

The Applicon 2D graphics world was signed 15 bit integer. The 16th bit was used to signify component selection. World units (aka AGS units) ranged from -16383 to 16383,  with the zero point (0,0) in the center of the screen. Users could define the number of world units per "natural" unit. For circuit board design, 1000 world units per inch gave a work area of approximately 32 x 32 inches with a resolution of 0.001 inch.  The setting was done with the SNTU (set natural units) command. 

The integer-based world unit structure of AGS/870 may seem limited by today's standards, but it was more than adequate for printed circuit board design. The standard Gerber Model 41 photoplotter of the era had a maximum plot area of 16" x 20" and an accuracy of 0.001 inch.

Grid settings of 100 mils (0.1 inch) or 25 mils (0.025 inch) would be typical while working. Components would snap to the nearest grid as they were drawn. A variable grid was also available, but rarely used.

Sixteen levels were available (1-16). Names could not be assigned to levels. Levels could be made editable (EDT), referenced (REF) or off (XEDT, XREF). One of seven colors could be assigned to each level.

The following drawing primitives were available for definitions:

 FXfixed dimension PCB pad (Gerber flash) from dynamic rectangle type R0
 S1stretchable in 1 dimension (not generally used)
 S2stretchable in 2 dimensions (a box or rectangle, used for fill)
 POLYlines or a series of vertices joined together by lines
 PATHpolys with definable width, for PCB traces or "metal"
 ARCarcs or full circles

The complex type CELL could be made using the primitives listed above, as well as text.

Text could be "free" (ETXT) or Variable attribute text (AVTA) used in Cells. In either case, text was attached to "nodes" made from a zero dimension FX called TRF. The nodes would show on plots, so they were placed on a level that was not edited or referenced (off).

The system included five modes: Control, Edit, Teach, Edit Component and Edit Text:
  1. Control mode (CTRL), was where drawings were loaded and saved, and system management commands were issued.
  2. Edit mode (EDIT) was where drawings were edited.
  3. Teach Mode (TEAC) was where tablet symbols, macros and tablet menus could be defined. All items were stored in the "dictionary".
  4. Edit Component Mode (ECMP), was where components were defined and edited. Components could be made from primitives, or cells could be made from previously defined components.  Cells were similar to blocks in AutoCAD and could have attached attributes to store part numbers, component ID's or other information. All component "definitions" were displayed with the DDEF command.
  5. Edit Text Mode (ETXT), was where text could be entered and edited, based on a previously defined text size. A multi-line text editor was provided.

Cells and other components were part of the drawing file, but could be purged if not needed (XDEF), or added to a drawing from other drawings (ADEF). Cells could be smashed (exploded) using the SMSH command.

There were three drawing "bins" where components could be temporarily stored (or removed using REMx commands, and later replaced using REPx and RPCx commands). Bins were very handy during drawing creation and editing. 

User Commands (UCMD's) or add-on programs could be called for special functions. In addition, IO Commands, such as Gerber Out (IO33), Gerber In (IO71), Disk I/O (IO70) and NC Drill (IO2) could be called.

The system did not have an "undo" command, but changes to a drawing file were not saved until a store command (STOR) was issued from control mode.

Click on the image below for the Applicon 2D Graphics Application System Command Summary.

System outputs were to a Calcomp pen plotter, 9-track magnetic tape for Gerber photoplotting and punched paper tapes for NC drilling on Excellon machines and Universal component insertion machines. System backups were made to 9-track magnetic tape.

The following shows a typical Applicon Color Graphics Terminal with tablet and pen:

In early 1983, Harper College in Schaumburg, Illinois established a CAD-CAM Training Center with an Applicon system, next to CADgineering Services.

Click here for the complete Harper College CAD/CAM Training Center brochure.

The following Potter & Brumfield Solid State Switching catalog cover from 1984 shows the CAD Room with three graphics terminals (a fourth was in the lower right, as well as a VT100 management terminal). The computer room is in the background. Above the CAD Room photo, a solid state relay 3D solid model is shown, along with the PCB design screen. Several solid state relays are shown, as well as I/O modules with associated mounting board.

Two rotating shifts with four operators per shift was typical. One shift was for the PCB designers and the other was for the mechanical designers. The CAD Room was frequently shown to company visitors who were always impressed with the high technology. 

The following is my Potter & Brumfield CAD/CAM equipment system configuration drawing from 1985.

Output from the Applicon system was in the form of a 9-inch magnetic tape for plotting on a Gerber photoplotter. Films were processed in a darkroom, using developer, stop bath and fixer and then washed and dried.

CADgineering had night-time access to a Gerber PC-800 system with an attached Model 41 Photoplotter. Gerber photoplotters were the standard back then. Ucamco now owns the Gerber photoplotter standard.

The following is the component side of a prototype board, of which several versions were designed. Through those design stages, we perfected the standards and process for auto-insertion of radial and axial components.

The following was a 2x scale check-plot of a double-sided board. The original was in color, with red for solder side, blue for component side and black for silk-screen:

One of my projects was an AMF bowling machine lane controller board that was based on a Motorola 6809 microprocessor. I used Applicon's auto-router software package. The first step was to draw a schematic, from which a netlist was extracted. Next, I created the board outline and tried placing components using auto-placement. Rats-nesting was used to find the best component locations. Although these tools were interesting, I found manual placement was best. After placing all the components, I manually routed power and ground. Then, using the batch auto-router, the system completed about 95% of the nets. The remainder of the board required manual routing.

Even though the routing software was impressive, the effort required to use it was extensive. I felt we could have delivered a higher quality design in less time by manual, on-screen routing. It took about 10 hours to auto-route the board, so if there was a problem, a whole day was spent correcting the issue and trying again. The router placed an excessive number of via's, many of which were manually removed while trying to finish the board. I believe I removed over 100 unnecessary vias. Routing through memory IC's had to be manually fixed. Today's auto-routing software is very fast, but in many cases it is still best to manual route. 

In the early 1980's, Applicon was a leader in the development of CAD/CAM for Printed Circuit Board design, along with ComputerVision and Racal-Redac. Many concepts, methods and techniques advanced by Applicon are still used today, in modern programs such as Altium Designer and CADsoft Eagle.

In 1985, I went to work for Siemens to setup a MS-DOS version of AGS/870 called Personal870 or P870 for short, by a company named Automated Images. The PC revolution was taking off. We used IBM PC/AT computers with EGA graphics (640x350) and Summagraphics tablets.

The Personal870 software was nearly identical to Applicon's AGS/870, but much faster. Productivity was high. Drawings were stored on 5-1/4" floppy disks and were very small in size. A dedicated CAD plotting station was setup with an attached HP 7580B pen plotter. A Microsoft BASIC program helped operators to quickly pick a drawing off of a floppy disk and send it to the plotter.  Insight Development's "PrintAPlot" software was later used to convert vector output to raster for HP LaserJet printers, but for larger requirements, pen plotting continued for many years.

Click here for my Applicon AGS/870 or Personal870 Standard Dictionary (pen-strokes and macros).

Check out these historic Applicon videos and pen plotting video on YouTube.