| 摘要 |
PURPOSE:To contrive higher efficiency in software debugging and in analysis of the cause of a fault, by providing a register group for checking a command sequence. CONSTITUTION:A register group 20 for checking a command sequence is provided, in addition to a character generator 10. The register group 20 comprises a sequence-checking counter 21, a page number counter 22 and a page sync counter 23. The first counter 21 sequentially counts up a plurality of commands when the commands are issued in a predetermined sequence, and finally returns to an initial value. The second counter 22 performs a counting operation when all necessary commands are issued on a page basis. The third counter 23 perform a counting operation by detecting the leading edge of a page sync signal. Since the command sequence is checked by the registers, it is made possible to discriminate between an abnormal condition due to a hardware fault and a software fault due to abnormality in the command sequence, and to contrive higher efficiency in software debugging and in analysis of the cause of a fault. |
