M38062M3-156FP MITSUBISHI [Mitsubishi Electric Semiconductor], M38062M3-156FP Datasheet - Page 31

• Manufacturer Part Number: M38062M3-156FP
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
• Manufacturer: MITSUBISHI [Mitsubishi Electric Semiconductor]

Bus control with memory expansion
The 3806 group has a built-in ONW function to facilitate access to
external memory and I/O devices in memory expansion mode or
microprocessor mode.
If an “L” level signal is input to the ONW pin when the CPU is in a
read or write state, the corresponding read or write cycle is ex-
tended by one cycle of . During this extended period, the RD or
___
WR signal remains at “L”. This extension period is valid only for
writing to and reading from addresses 0000
0440
memory expansion mode, and only read and write cycles are ex-
tended.
Fig. 30 ONW function timing
AD
16
:
Period during which ONW input signal is received
During this period, the ONW signal must be fixed at either “H” or “L”. At all other times, the input level of the ONW
signal has no affect on operations.
The bus cycles is not extended for an address in the area 0008
is received.
to FFFF
15
_____
to AD
ONW
WR
RD
16
0
in microprocessor mode, 0440
Read cycle
_____
_____
Dummy cycle Write cycle
16
16
to 0007
to YYYY
16
___
16
and
in
Read cycle Dummy cycle
16
to 043F
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
16,
regardless of whether the ONW signal
MITSUBISHI MICROCOMPUTERS
Write cycle
3806 Group
31