In a keyboard entry word processing system, text is stored in a recirculating refresh memory along with a carriage return code at the end of each line. The text is displayed on a CRT screen. A cursor symbol, also displayed on the screen, may be moved by keyboard control to designate a particular character position on the screen where editing is to occur. When the cursor is within the field of displayed text, characters may be edited at the location in memory corresponding to the location of the cursor on the screen. When the cursor is outside the field of displayed text, the cursor is first "found" by altering the refresh memory to provide a new memory location corresponding to the cursor location, and then editing is performed at the new memory location.
In providing overlapped displays of characters and graphics on a display unit, character data are arranged in the order of rows, while graphic data are divided into blocks corresponding to the rows of the character data and the data, which are extracted from the respective blocks in the order of lines, are arranged for each line in the order of the blocks. This eliminates the necessity of providing a remainder of address for each row which is instead provided at the end of each line of the graphic data so as to permit the transition to the next line by shifting the high-order digit of the address, and accordingly the utilization efficiency of a RAM is increased.
A computer terminal employs a CRT display, a micro-processor, and a random access memory which both stores character codes for information to be displayed on the CRT screen and serves as working storage for the processor. To generate a line of text across the display the processor loads a memory address counter with the address of a memory location containing the code for the first character of the line. The counter is incremented in timed relation to the generation of the display and sequentially outputs consecutive memory addresses in which the consecutive character codes forming the line are stored. During the generation of the line the activity of the processor is inhibited. Following generation of the line the processor regains access to the RAM and tends to I/O duties or modifies the display memory contents until it passes control of the RAM back to the address counter for generation of another line of display.
An electronic typewriter provided with a display unit giving visual display of data in a number of positions of characters shorter in length than one line of characters printed on a sheet of paper which includes a cursor for indicating the next following position of data input. The cursor may be shifted out of the display unit when necessary, and when the data imputted to the last position in the display unit is dead key data, the position of the dead key data is indicated by the cursor, so that the display unit can display data greater by one character than display units of the prior art.
A cursor movement control a screen-segmented display apparatus in which the cursor is moved line by line within one divided section. The apparatus comprises a horizontal cursor register for storing the horizontal position of the cursor on display, a vertical cursor register for storing the vertical position of the cursor on display, a starting column register for storing the cursor starting column on one divided section, and a last column register for storing the cursor last column on the section. The contents of the horizontal cursor register are changed by pulses of an external pulse source generated in response to a command for moving the cursor. When the contents of the horizontal cursor register coincide with that of the last column register, the horizontal cursor register is stored with the starting column of the starting column register and at the same time the contents of the vertical cursor register are changed to set the cursor forward by one line.
A displaying apparatus comprises a CRT capable of displaying picture elements of n rows by m columns and a VRAM (Video RAM). The VRAM comprises a CRT area having addresses of n rows by m columns identical to those of the CRT and a first and a second menu areas formed at both right and left sides of this CRT area. Display data of a formatted document is stored in the CRT area, being converted into a video signal to display an image of the formatted document by means of the CRT. To point a blank space of the formatted document, as cursor is further displayed on the CRT. When a menu display is required, the data of the required menu is stored in the first and the second menu areas, being converted into a video signal. A CPU decides the leading address of the VRAM to start the display so that the cursor and the menu are displayed simultaneously on the CRT screen. Thus, an erasure of the cursor from the CRT screen can be prevented even when the menu is displayed.
