Technical information
62
3886 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
BUS CONTROL AT MEMORY EXPANSION
The M38867M8A/E8A have a built-in ONW function to facilitate
access to an external (expanded) memory and I/O devices in
memory expansion mode or microprocessor mode.
If an “L” level signal is input to the P32/ONW pin when the CPU is
in a read or write state, the corresponding read or write cycle is
extended by one cycle of φ. During this extended term, the RD
and WR signals remain at “L.” This extension function is valid only
for writing to and reading from addresses 000016 to 000716 and
044016 to FFFF16, and only read and write cycles are extended.
Fig. 64 ONW function timing
φ
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—
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