339 Display Brochure

The Type 339 Programmed Buffered Display is a precise and powerful incremental Cathode Ray Tube (CRT) display option for PDP-9 general-purpose computer systems. It functions as a multi-processor system, interfacing with the PDP-9 via a Direct Memory Access (DMA) channel and sharing core memory, allowing the display to operate independently by "cycle-stealing" instructions while the PDP-9 runs other programs.

The display system is capable of rapidly converting digital data into graphic or tabular forms, drawing vectors and characters, and scaling images. Its key features include:

• Precision and Speed: High spot stability (±0.05 inches) and a small spot size (0.015 inches) ensure accurate rendering. It offers fast plotting rates for points (as low as 20 microseconds per point), vectors, and characters.
• Operational Versatility: Supports multiple data state modes (e.g., increment, vector, point, graph-plot, character) and various control state instructions for setting parameters and managing display execution.
• Visual Control: Provides four scale factors and eight distinct, uniform intensity levels, with lines constructed from discrete points to maintain consistent brightness.
• Interactive Input: Comes standard with a light pen for direct interaction and a push-button control box for operator commands and interrupts.
• Automatic Scissoring: Allows users to create large drawings (up to 75"x75") but view only a selected 9-3/8"x9-3/8" portion at a time, with an automatic method for shifting the viewing area.

Optional enhancements include:

• Character Generator (Type VC38): Simplifies and speeds up the drawing of alphanumeric characters.
• Slave Mode (Type VS38): Enables one Type 339 processor to drive up to seven display surfaces.
• Search Logic (Type VF38): Facilitates quickly finding and modifying specific instructions within display files.
• Zoom Mode (Type VZ-38): Compresses an entire 75"x75" drawing to fit on the standard display screen.

The PDP-9 provides the necessary computing power, expandable memory, and a comprehensive software system (including FORTRAN IV, assemblers, monitors, and debugging tools) to support the Type 339. This integrated system is well-suited for applications such as automated design, information retrieval, computer-aided instruction, and man/machine communication research.