| 摘要 |
<p>PURPOSE:To select easily an input character data by providing a display device representing a light pen detection enable state to a light pen detection field on a picture plane. CONSTITUTION:When the operator indicates an n-row/m-column designated character [?] of a display section 5 by using a light pen, an AND gate 9 is turned on by a light pen detection pulse signal 20 and a light pen switch on signal 21 from a light pen 6, the content of a display counter 7 is stored in a register 8 and an interruption FF10 and a mask FF11 are set. A processing unit 1 receives an interruption request signal 24, decides the cause of interruption and uses a light pen processing program to apply processing. When it is decided as a light pen detection interruption, the content of the register 8 is read and the value is corrected in column direction. Based on the corrected display screen address, a light pen detection field at a near column on the same row and in the light pen detectable state is searched in a refresh memory 2.</p> |
