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MX
3500
Pin
No
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
Polarity
Signal
Name
SYSR
FD3
COAB
RO1B
GND
Vcc
RO2B
R03B
RDB
CLK
R04B
MPX
GND
CASB
GND
INTB
IN/OUT
IN
IN
IN
OUT
IN
IN
OUT
IN
OUT
OUT
IN
OUT
IN
OUT
Function
System
reset
signal.
Used
to
reset
I/O
port
in the
MMR.
(System
Reset)
Input
from
the
sytem
assignment
dip
switch.
"See
the dip
switch description, provided
separately.
Shared
RAM
select
signal.
Address
of the
shared
RAM is
*F800-#FFFF
for the
main
CPU
(Common
RAM
Address)
Select
signal
for 8KB
area
allocated
to
slot
1.
Valid
when
SD2 is
active (ROM
based
BASIC)
and SD3
(RAM
based
BASIC)
(ROM
1)
Ground
5V
supply
Select
signal
for 8KB
area
allocated
to
slot
2 or 3
Valid
when
SD2 is
active (ROM
based
BASIC)
and SD3
(RAM
based
BASIC).
(ROM2,
3)
Read
signal
from
the
main CPU.
(Read)
EAIT signal generation
clock.
(Clock)
Select
signal
for 8KB
area
allocated
to
slot
4.
Valid
when
SD2 or SD3
(RAM based BASIC)
are
active.
(ROM
4)
RAS/CAS
address
switching
signal
for the
main
CPU
DRAM.
High:
Row
address Low: Column
address
(Multiplex)
Ground
CAS
(Column
Address) signal
for the
main
CPU 64K
DRAM.
•Refresh
for the RAM
only.
(Column
Address
Select
Buffer)
Ground
(Interrupt)
Not
used
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22
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