| 摘要 |
<p>PURPOSE:To realize the conversion of a memory map of a system, by installing a converting switch, a circuit that applies temporarily the resetting to a CPU and a multiplexer that varies the input/output relation of an address decoder respectively. CONSTITUTION:A CPU19 is reset according to the state of a switch 30 and then started at the address 0000. For instance, when the output of a gate 31 is set at HIGH, a decoder 24 decodes the input 45. When the input 45 is 00, 10 and 11, outputs 49, 48, 47 and 46 are selectd respectively. Then an RAM27 and an ROM29 are selected when the switch 30 is in the state as shown in the diagram. When the switch 30 is set in the state opposite to that as shown in the diagram, the output of a gate 35 sets a latch 36. Then the CPU19 select only ROM28 and gives an access to it. In case the CPU19 jumps to a prescribed memory region and then resets a latch 36 by an input/output instruction, an access is given to the RAM27 and ROM28 respectively.</p> |
