| 摘要 |
A data retrieval system, intended principally for allowing a computer to make use of the viewdata or teletext information services, stores selected portions of data corresponding, for example, to one of the pages of transmitted information and feeds the data one byte at a time to the computer in the order in which alphanumeric characters represented by the bytes appear on the page. To do this, data selected in real time by a teletext or viewdata decoder (12) is written to a random access memory (16) during a predetermined time interval sufficient to accumulate a page of information in the memory, and stored in the memory (16) in an interlaced line format. After the time interval, a microprocessor (18), with the aid of a look-up table, reads out the lines of data from the memory one byte at a time in the order that the lines appear in the page, and converts these bytes to a serial ASCII coded data stream suitable for storage, processing or display in a number of different types of host computer. The system also allows commands, such as page numbers, to be converted to a form suitable for controlling the selection of data in the decoder (12). |
