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DEC GT40 running Lunar Lander
Screenshot of an emulated GT40 with an Archimedean spiral and its FOCAL-11 source code

DEC GT40 is a VT11 vector graphic terminal produced by the Digital Equipment Corporation, first introduced in October, 1972 (selling for “under $11,000”).[1]


The DEC GT40 consists of:[2]

  • CPU: KD11-B (PDP-11/05)
  • VT40 display processor, including bootstrap ROM (same modules as VT11, but instead of the four-slot backplane, this has a nine-slot backplane to include the CPU and memory)
  • MM11-L 8K word core memory (MM11-K 4K word core memory on GT40-Bx models)
  • DL11-E asynchronous line interface
  • LK40 keyboard
  • VR14-LC X-Y monitor (or -LD for 230 V)
  • 375 light pen

Because the GT40 contained a PDP-11 class computer, the terminal could also serve as a computer in its own right, IEEE Computer wrote:[1]

The GT40 may be used either as a stand-alone graphics system or as a remote terminal interacting with various types of host computers. John Mucci, marketing manager for the DEC graphic-11 group, sees the GT40 being particularly useful in the areas of graphic research, design, engineering, architecture business information systems and many other uses needing a fast, low-cost graphics display.

In a stand-alone configuration, the PDP-11/10 within the terminal can be expanded with additional memory and any PDP-11 family peripheral to build as complex a system as necessary. “In fact, the central processor used in the GT-40 can be any PDP-11 family processor,” says Mucci, ”since the display processor is interfaced via the PDP-11's Unibus.”

Other models[edit]

Other versions, using different PDP-11 CPUs and/or video processors:


VT11 vector graphics terminal using a PDP-11/10.


VT11 vector graphics terminal using a PDP-11/40.


VS60 vector graphics workstation using a PDP-11/34a and VT48 graphics processor.

See also[edit]

External links[edit]


  1. ^ a b IEEE Computer, 5(6), Nov. 1972, pp. 61–62
  2. ^ "DEC GT40 Graphic Display Terminal". 090509