Abstract: When display data are written into the terminal's display memory, the data indicative of the display coordinate are converted from the normalized values to the absolute values of the NTSC system or PAL system and are then written into the corresponding addresses of the display memory, so that regardless of the fact that the display is of the NTSC system or of the PAL system, the figure can be displayed with the correct aspect ratio. Further, when the coordinates are converted, the conversion is carried out such that the display resolution is regarded as the highest one, so that even if the resolution of the display is increased by increasing the capacity of the display memory, it is not necessary to change the conversion algorithm. For displays having less than full resolution capability, the display data is scaled by omitting some of the converted data when writing it into the display memory.

Abstract: In a two-way communication system having first and second communication terminals, a telephone apparatus at each terminal for two-way telephone service and a picture communication apparatus at each terminal for providing users with visual images of each other; the picture communication apparatus includes video cameras for generating video signals to be transmitted, display apparatus for displaying the visual images, a control apparatus for controlling transmission and reception of the video signals, and a line drawing input apparatus connected to the control apparatus for generating a line signal representing the line drawing and which is transmitted with the video signals from the control apparatus.

Abstract: A terminal which is capable of receiving, converting and displaying both NAPLPS and PRESTEL coded signals and which includes means for invoking NAPLPS control and character codes, corresponding to the same, received PRESTEL codes, to an in-use table from NAPLPS code look-up tables at the terminal and for separately processing, decoding and converting PRESTEL attribute codes to produce corresponding NAPLPS codes.