Technical information
APPLICATION
2.4 Processor mode
2-50
3800 GROUP USER’S MANUAL
2.4.3 Processor mode application examples
(1) Application example of memory expansion in the case where the ONW (One-Wait)
function is not used
Outline : The external memory is accessed in the microprocessor mode.
At f(X
IN) = 8 MHz, an available RAM is given by the following :
• OE access time : ta (OE) ≤ 50 ns
• Setup time for writing data : tsu (D) ≤ 65 ns
For example, the M5M5256BP-10 whose address access is 100 ns is available.
Figure 2.4.3 shows an expansion example of a 32K byte ROM and a 32K byte RAM.
Fig. 2.4.3 Expansion example of ROM and RAM
3800 group
CNV
SS
ONW
AD
15
8
8
8
AD
14
AD
0
DB
0
DB
7
RD
WR
M5M27C256AK-10
M5M5256BP-10
CE
A
0
–A
14
D
0
–D
7
OE
A
0
–A
14
DQ
1
–DQ
8
OE W
8MHz
V
CC
= 5.0V
±
10 %
0000
16
8000
16
0440
16
0040
16
0008
16
FFFF
16
External RAM area
(M5M5256BP)
SFR area
Internal RAM area
External RAM area
(M5M5256BP)
External ROM area
(M5M27C256AK)
Memory map
74F04
S
–
–
15
8
2 , P3
1
EPROM SRAM
2
P3
0
P4
P5
P6
P7