| 摘要 |
PURPOSE:To make self-diagnosis rapid and easy without increasing a memory capacity, by storing a self-diagnostic program in an external memory and providing an external memory selection order circuit to the external memory. CONSTITUTION:When an external memory 1 is connected to an external memory storing part, the output signal Z of an external memory selection order circuit 10 becomes a low level from a high level by the function thereof. As a result, the output signal Y of a memory access change-over means 14 changes from a high level to a low level and the output signal X of the means 4 changes from a low level to a high level. From this point of time, a built-in memory 3 becomes a stop state and the memory part 1A of the external memory 1 becomes an operating state. A self-diagnostic program is outputted to a data bus 11 from the memory part 1A on the basis of the order sent through an address pulse 12 to start the self-diagnosis of a printer. |
