M38867E8AHP MITSUBISHI [Mitsubishi Electric Semiconductor], M38867E8AHP Datasheet - Page 62

• Manufacturer Part Number: M38867E8AHP
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER??
• Manufacturer: MITSUBISHI [Mitsubishi Electric Semiconductor]

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 P3
in a read or write state, the corresponding read or write cycle is
extended by one cycle of . 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 0000
0440
Fig. 64 ONW function timing
62
* T e r m w h e r e O N W i n p u t s i g n a l i s r e c e i v e d .
D u r i n g t h i s t e r m , t h e O N W s i g n a l m u s t b e f i x e d a t e i t h e r “ H ” o r “ L ” . A t a l l o t h e r t i m e s , t h e i n p u t l e v e l o f t h e O N W
s i g n a l h a s n o a f f e c t o n o p e r a t i o n s . T h e b u s c y c l e s i s n o t e x t e n d e d f o r a n a d d r e s s i n t h e a r e a 0 0 0 8
b e c a u s e t h e O N W s i g n a l i s n o t r e c e i v e d .
A D
16
to FFFF
1 5
O N W
— A D
W R
R D
16
0
, and only read and write cycles are extended.
R e a d c y c l e
*
2
/ONW pin when the CPU is
D u m m y c y c l e W r i t e c y c l e
16
to 0007
16
and
*
R e a d c y c l e D u m m y c y c l e
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
W r i t e c y c l e
*
3886 Group
1 6
t o 0 4 3 F
1 6 ,