A CRT Display with Light Pen and Its Computer Interface

This paper describes the main features in the design and construction of a CRT display device which is connected to the CDC 3600 computer at the TIFR. The device has capabilities to display texts, graphs and other information automatically. The display size is 10 × 10 in. A light pen is provided which enables a display user to point at a picture part or draw a free-hand sketch on the CRT face. A group of 32 push buttons is also provided which enables a display user to choose an ‘action’ and guide the course of computation from the display console. The device is constructed using discrete components. A total of about 350 printed cards, each with about ten transistors and diodes, is used in the construction of the device. The entire design and fabrication of the logical circuits and CRT electronics was done at the TIFR. The display is in operation for the past two years. The paper concludes by presenting the results obtained and with a short discussion on the ways of interface design in interactive graphica...