650
Table B.2
Pin States in Address Space Accesses (cont)
DRAM Space
16-Bit Space
2-CAS System
2-WE System
Pin Name
8-Bit
Space
Upper
Byte
Lower
Byte
Word
Upper
Byte
Lower
Byte
Word
CS7
–
CS2
,
CS0
High
High
High
High
High
High
High
CS1
Low
—
—
—
Low
Low
Low
RAS
RAS
RAS
RAS
RAS
RAS
RAS
RAS
CASH
High
CASH
High
CASH
High
High
High
CASL
CAS
High
CASL
CASL
CASL
CASL
CASL
AH
Low
Low
Low
Low
Low
Low
Low
RD
R
Low
Low
Low
Low
Low
Low
Low
W
High
High
High
High
High
High
High
WRH
R
High
High
High
High
High
High
High
W
High
High
High
High
Low
High
Low
WRL
R
High
High
High
High
High
High
High
W
Low
Low
Low
Low
High
Low
Low
A0
A0
A0
A0
A0
A0
A0
A0
A21–A1
Address Address
Address
Address
Address
Address
Address
AD15–AD8
High-Z
Data
High-Z
Data
Data
High-Z
Data
AD7–AD0
Data
High-Z
Data
Data
High-Z
Data
Data
DPH
High-Z
Parity
High-Z
Parity
Parity
High-Z
Parity
DPL
Parity
High-Z
Parity
Parity
High-Z
Parity
Parity
R: Read
W: Write
—: The
CS1
pin is used as the
CASH
signal output pin.
RAS
: When a row address is output from A21–A0, an address strobe signal is output.
CAS
: When a column address is output from A21–A0, an address strobe signal is output.
CASH
: When a column address is output from A21–A0 during an upper byte access, an address
strobe signal is output.
CASL
: When a column address is output from A21–A0 during a lower byte access, an address
strobe signal is output.
Parity: When a DRAM space parity check is selected with the parity check enable bits
(PCHK1,PCHK0) in the parity control register (PCR), this pin is used as the parity pin.
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