| 摘要 |
<p>PURPOSE:To test one-chip microcomputers at a factory completely by testing the output states of all I/O ports. CONSTITUTION:In addition to a state controlling circuit TC provided with a test terminal TO and changeover switches SW1 and SW2 (not shown in figure), an I/O port selecting circuit provided with a port selection terminal T5 and changeover switches SW3 and SW4 (not shown in figure) is provided. Namely, the changeover switches SW1 and SW2 are those switching an input of an instruction PLA to an I/O port side or ROM output terminals t0-t7 (not shown in figure), but the change- over switches SW3 and SW4 switch their I/O port groups. When the switch SW3 is on and the SW4 is off, I/O ports I/O0-I/O7 are selected and when the SW3 is off and the SW4 is on, I/O ports I/O8-I/O15 are selected.</p> |
