“A microprocessor display controller for combining refresh and storage tube graphics” by Satterfield, Rogers and Rodriguez

This paper describes a stand alone graphics system utilizing a microprocessor based display controller with the capability of combining refresh with storage tube graphics. This combination is accomplished by utilizing the Write-Thru feature of a Tektronix 4014 display terminal. The display controller is a typical Z-80 microprocessor system interfaced to the 4014 by a standard Tektronix parallel interface. A portion of the Z-80 memory is used as the display buffer, allowing it to be divided into store and non-store (refreshed) segments. The microprocessor performs the conversion from the simple integer X, Y coordinates in the display buffer to actual Tektronix drawing commands. A second Z-80 microprocessor is used to perform graphical transformations and transfer the data from the PDP-11 host to the Z-80 display controller. The operations performed by the second microprocessor include translation, rotation and scaling. These operations are implemented by matrix multiplication of the user data by a user specified transformation matrix. The stand alone capabilities of the graphics system is made complete with interactive devices such as a tablet, analog dials, and function switches interfaced directly to the host computer.

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