| 摘要 |
<p>The hard copy printing of data that is being simultaneously displayed on a cathode ray tube and outputted therefrom requires the buffering of such data in order to compensate for the varying data rates existing between such devices and also to convert the display data, which is normally in interlaced form, into a data format that can be handled by the printer. In order to permit such hard copy printing of such cathode ray output data, data signals are received by a latch 932) and thereafter transmitted to a buffer 934) having two parts (36, 38) so that the display data can be stored in the memory as a sequence of horizontal strips under control of a write address counter (42) and a multiplexer 940), with the strip data in one memory part being read out under control of a read address counter 944) and the multiplexer to the printer, the reading being interrupted by a read/write logic (46) in intervals when the data for the next adjacent strip is being written into a memory part is done on an alternate line basis under control of an external signal (FIELDO^/), with the omitted lines being filled in a subsequent write operation so as to convert the interlaced input to a standard printer format. At appropriate times, the two parts of the memory are switched so that the readout from memory (34) on output (20) for the printing is carried out from the part into which information has just been written, and subsequent writing takes place in the part of the memory which has been cleared during the preceding read operation.</p> |
