Abstract: Disclosed is a CRT display apparatus of a raster scanning type which includes a microprocessor as a unit for data handling or processing in an input/output control part for controlling data transfer with a computer and/or keyboard, the operations of the microprocessor being controlled by a microprogram stored in a microprogram memory. A timing control unit or part for producing various timing signals for controlling displays is connected to the microprocessor through a data bus and an address bus so that control parameter for the various timing operations can be set through the microprogram. The timing control part comprises programmable control registers, counters for generating timing signals and coincidence detectors or comparators for detecting coincidence between the outputs from the control registers and the timing signals from the associated counters.

Abstract: A raster scan type CRT display system is disclosed which has a randomly accessable refresh memory. The display system comprises column and row start address registers for defining a read start address for the refresh memory, column and row address counters for counting the contents of the column and row start address registers as start positions to generate a read address of the refresh memory for display, column and row cursor registors for defining a data entry position on a CRT screen, and column and row address generators for generating an entry address for the refresh memory based on the contents of the column and row start address registers and the contents of the column and row cursor registers, whereby a rolling or shifting of the image is effected and the refresh memory can be accessed by a processor for read/write operation without the need to monitor the image rolling.

Abstract: A display system is disclosed wherein a refresh memory is divided into a plurality of blocks of bytes so that a micro-processor can access the blocks byte by byte while display data of the plurality of blocks are assembled by word so that the display data are accessed word by word. The access by the micro-processor and the access for display are time-shared at a timing of one half of one character display to avoid wait time for the accessing.

Abstract: A light pen detection system used for a display system using a cathode ray tube (CRT) in which the operation for detecting the character display position on the CRT face is started when the operation switch of the light pen is turned on, and repeatedly progresses in synchronism with the picture repetition rate, and when a position marker is displayed at the character display position detected through such detecting operation, the operation switch of the light pen is turned off thereby to stop such detecting operation, whereby the character display position detected is obtained as the up-to-date one indicated by the light pen.