| 摘要 |
PURPOSE:To simply detect the erroneous operation of the entire character generating system and to prevent the erroneous output by comparing a check code read out when a font of one raster is written in a buffer with a value calculated by an adder previously. CONSTITUTION:A check code generator 4 transfers output information of one line from an input buffer 3 to a column buffer 5, a check code read out from a font memory 1 is simultaneously calculated, and when a line feed code is detected, the result is stored in a check code register 6. A check code read out simultaneously with the reading of the font is fed by a signal line to an adder 9, and when a line feed command is detected, a check code calculated value calculated in advance by a check code generator 4 is compared by a comparator 10 with the output of the adder 9. When these values become coincident, it is judged as that no erroneous operation occurred. |
