| 摘要 |
PURPOSE:To improve the noise margin of an apparatus by using a microcomputer, where a data bus line and an address bus line connecting a CPU and a memory are pulled up, in a control part. CONSTITUTION:A control part 1 of a printer consists of a CPU2, a memory 3, a data bus line (8 bits) 4, an address bus line (16bits) 5, a control bus line (which is not shown in Fig.) (these busses connects the CPU2 and the memory 3), and interfaces 6 and 7. The data bus line 4 and the address bus line 5 are pulled up by pull-up resistances R0-R7 and R8-R23 to take a countermeasure against noise. If a noise is mixed to change the value of a stack pointer when the CPU2 executes instructions of a subroutine, the operation of the CPU2 is returned to the step of CALL instruction by the action of the pulled-up data bus line 4, and the subroutine is executed repeatedly. |
