A full page display device for a text processing system in which a text stream input by way of a keyboard is stored and displayed to the operator on a display device including a cathode ray tube, the electron beam of which is modulated and scanned in a series of horizontal traces to produce an image of the text line on the screen of the display device. The system comprises storage means which includes a plurality (four in a specific embodiment) of separate storage devices. In the specific embodiment, when the storage devices are accessed for display, one character is accessed simultaneously from the same location in each of the storage devices. The data is latched and coupled to a character generator to read out character dot pattern data which is latched and then interleaved with the data from other accessed character data by transferring the data one character at a time in parallel to a serializer. The data out of the serializer forms a serial bit stream which is coupled to the cathode ray tube to modulate the intensity of the beam in synchronism with the sweep to display the selected character data.
In a bit mapped raster scan digital display system, a number of maps each contain a single component of the display data and are read together to provide sets of bytes, each set representing eight pel defining groups. A compare system is provided for determining when a pel group in a set of bytes compares with a reference pel defining group. For the, or each, pair of maps, the compare system compares all bits of the two bytes of data with the associated bit of the reference group to provide outputs when a corresponding bit in each of the bytes compares with the two reference bits. When more than two maps are employed the compare outputs related to all of the pairs of maps are combined to provide an output signal when a pel group in a byte from the maps compares with the reference bits. In a modification of the system the comparison can be made between one or more of the maps and the corresponding bit or bits of the compare data.
A video display control unit controls characters to be displayed on a sequential scanning display unit (4). Namely, it reads address-specifying information and attribute information from a video memory (5) along scanning sequence of a screen in a continuous and address-unit time-divisional manner on the basis of address signals from a memory address counter (6). The read attribute information is outputted on a multiplex bus (42) through a gate (34) and delayed by a predetermined period by a pipeline register (40) to be supplied to a video signal encoder (18). The read address information is supplied to a character generator (16) so that character information is read from the character generator (16). The character information is outputted on the multiplex bus (42) through a gate (36) and delayed by a predetermined period in a pipeline register (38) to be supplied to the video signal encoder (18). The video signal encoder (18) outputs video signals on the basis of the attribute information and the character information.
An image data output apparatus having a plurality of memories, a plurality of latch circuits corresponding in number to the memories, a data selector, and a timing pulse generator. A plurality of pixel data corresponding to a plurality of pixels constituting an image are stored in the memories. A plurality of read clock signals having different timings are supplied from the timing pulse generator to the memories to read pixel data from the memories at different timings. The read-out pixel data are applied at different timings to the latch circuits. A plurality of latch signals having different timings are supplied from the timing pulse generator to the latch circuits to thereby make definite the pixel data at the latch circuits at different timings. The definite pixel data are supplied to the data selector to which a select signal from the timing pulse generator is applied. Thus, the pixel data are sequentially outputted one after another from the data selector.
A variable size and position dialog area or alphanumeric area is provided for the screen of a computer terminal in response to a single line of data from a data bus, containing the numerical indication of the initial line of a plurality of lines of alphanumeric information to be displayed and the numerical indication of the last line of a plurality of lines of alphanumeric information to be displayed. The numerical indications are successively loaded to a state machine operating as a counter which disables the alphanumeric display during a first counting operation and enables the alphanumeric display for the duration of a second counting operation.
