Abstract

A terminal device having a keyboard and a display device and connected to a central processing unit through a line, wherein a display screen of the display device is divided into a first field and a second field and on-line processing data is displayed in the first field while off-line processing data is simultaneously displayed in the second field so that an operator can operate the keyboard to prepare a document in an off-line mode while the operator refers to the on-line data. The data displayed in the first field is a portion of the on-line processing data stored in a first buffer memory and the data displayed in the second field is a portion of the off-line processing data stored in a second buffer memory. The sizes and the locations of the data read from the respective buffer memories are designated by parameters on a display control table and the parameters are alterable by operation of the keyboard. Thus, the sizes of the first and second fields on the display are variable and the respective fields can be independently scrolled.