122 HITACHI
set to 1 to use the address multiplex function, bits A23–A0 are multiplexed and output from pins
A15–A0, so a maximum 16-Mbyte space can be used. When DRAM space is accessed, the
CS1
signal is not valid and the pin function controller should be set for access with
CAS
(
CASH
and
CASL
) and
RAS
signals.
H'9000000
H'93FFFFF
H'9400000
H'97FFFFF
H'9800000
H'9BFFFFF
H'9C00000
H'9FFFFFF
H'1000000
H'1400000
H'1800000
H'1C00000
H'13FFFFF
H'17FFFFF
H'1BFFFFF
H'1FFFFFF
A27 = 1:
16-bit space
Shadow
Shadow
Shadow
External
memory
space
(4 Mbytes)
A27 = 0:
8-bit space
Valid
address
A21–A0
(A23 and
A22 not
output)
CS1
valid
DRAME = 0 or DRAME = 1, MXE = 0
Logical address space
H'9000000
H'9FFFFFF
H'1000000
H'1FFFFFF
A27 = 1:
16-bit space
DRAM
space
(maximum
16 Mbytes)
DRAME = 1
Logical address space
Actual space
A27 = 0:
8-bit space
Multiplexed
(MXE = 1):
16-bit space
Not multi-
plexed
(MXE = 0):
4 Mbyte
space
CS1
not
valid (
CAS
,
RAS
output)
Actual space
Shadow
Shadow
Figure 8.6 Memory Map of Area 1
Areas 2–4:
Areas 2–4 are the areas where addresses A26–A24 are 010, 011 and 100, respectively,
and their address ranges are H'2000000–H'2FFFFFF and H'A000000–H'AFFFFFF (area 2),
H'3000000–H'3FFFFFF and H'B000000–H'BFFFFFF (area 3), and H'4000000–H'4FFFFFF and
H'C000000–H'CFFFFFF (area 4). Figure 8.7 is a memory map of area 2, which is representative
of areas 2–4.