| 摘要 |
PURPOSE:To make the operator of this device recognize misoperation, by providing a CRT display controller equipped with a line register, video RAM, etc., and detecting the misoperation when the misoperation takes place, and then, changing the displaying form of a displaying picture. CONSTITUTION:When the operator of this device depresses a key 'CENTER' for the purpose of centering a character string 'CENTERING' between the left and right margins, a line register LR in a CRT display controller CRLTC is checked. Namely, whether or not a character string exists on a line corresponding to the value of the line register LR is checked on a statement memory SM and, when the character string exists, all corresponding bit information on the 25th line lf a video RAM VRAM is inverted as misoperation. Therefore, the 25th line of the displaying picture of a CRT is white-black inverted. Since misoperation is detected and the displaying form of a displaying picture is changed in such a way when the misoperation takes place, the operator of this device can recognize the misoperation.
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