Data General Corporation's Nova and Eclipse line of 16 bit mini Computers. Sketches or layouts of electronic system were first manually drawn on mylar or paper to scale and were placed on large backlit 48 by 60 inch table digitizers. Using a moving stylus, these layouts were organized in layers, first placing the smaller common and custom circuits, created in a library, then manually traced their interconnecting circuitry on further layers, the completed layout then stored in computer files. Printed Circuit Boards (PCB's) and Small Scale Integrated Circuits (SSIC) were manually traced buy an operator, usually a draftsman or electronic engineer then plotted on a large pen plotter (In later years to faster Electrostatic Plotters) to be visually inspected to confirm that the physical layout properly matched the schematic. Once the layout and schematics final edits were manually checked to confirm their accuracy, the multiple layers of the physical circuitry were sent to a film plotter to create masks for fabrication. The central processing unit consists of a minicomputer, a computer console and page printer, a magnetic tape transport and a magnetic disk memory unit. Other optional peripheral devices such as card readers and paper tape punches are also available. These components are interfaced with Calma-designed and manufactured controllers, and integrated into a single unit with system software designed and programmed by Calma. An operator station consists of a digitizing device, an interactive cathode ray tube (CRT) display unit, coordinate readouts and a keyboard. The main difference between stations is in the type of digitizing input station used. The Calma digitizer is a backlit 48 by 60 inch table. To digitize analog graphical data directly on computer-compatible medium, the operator of the digitizer manually traces graphical data with a moveable stylus. The graphic tablet has a smaller surface and is operated with an electromechanical graphic pen and were used primary to edit an electronic layout once it was digitized. The digitizing input station is linked by system software to the CRT display, which allows an almost instantaneous display of any segment of the source drawing or a graphic element from the library. The CRT display also has windowing and magnification capability. An alphanumeric keyboard is used for entering text, scaling information, dimensions and commands, and an optional functional keyboard is available for entering frequently used functions, symbols and macro commands. The output most commonly used in Calma's systems is a