| 摘要 |
PROBLEM TO BE SOLVED: To make it easy to specify the cause of abnormal operation in such a case by taking an operation diagnosis of a mounted memory in an idle period wherein a task needed for image formation temporarily stops. SOLUTION: A free memory area consisting of a prescribed number of bytes is obtained in an extension RAM 20. The memory capacity which is obtained here is about several K bytes exceeding the capacity of a cache memory in a CPU 11. Then it is judged whether or not the addresses of the obtained free memory are proper. At this time, when it is judged that the addresses are not proper, that is displayed at an LCD display part 15. When it is judged that the addresses are proper, data which are written are read out of the same memory cells at the same timing with ordinary operation and it is checked whether the data are all 0×55 (55 in hexadecimal notation). At this time, if there is even one piece of different data, the LCD display part 15 displays the abnormality of the extension RAM 20. |
