CY7C138 CYPRESS [Cypress Semiconductor], CY7C138 Datasheet - Page 13

• Manufacturer Part Number: CY7C138
• Description: 4K x 8/9 Dual-Port Static RAM
• Manufacturer: CYPRESS [Cypress Semiconductor]

Table 1. Non-Contending Read/Write
Table 2. Interrupt Operation Example (assumes BUSY
Table 3. Semaphore Operation Example
Set Left INT
Reset Left INT
Set Right INT
Reset Right INT
No action
Left port writes semaphore
Right port writes 0 to semaphore
Left port writes 1 to semaphore
Left port writes 0 to semaphore
Right port writes 1 to semaphore
Left port writes 1 to semaphore
Right port writes 0 to semaphore
Right port writes 1 to semaphore
Left port writes 0 to semaphore
Left port writes 1 to semaphore
CE
H
H
H
X
L
L
L
R/W
X
H
X
H
X
L
Inputs
OE
H
X
X
X
X
L
L
Function
Function
SEM
H
H
H
L
X
L
L
High Z
Data Out
High Z
Data In
Data Out
Data In
Outputs
I/O
0-7/8
Power-Down
Read Data in
Semaphore
I/O Lines Disabled
Write to Semaphore
Read
Write
Illegal Condition
Operation
I/O
R/W
X
X
X
L
0-7/8
1
0
0
1
1
0
1
1
1
0
1
Left
L
CE
=BUSY
X
X
L
L
13
Left Port
I/O
OE
R
0-7/8
X
L
X
X
=HIGH)
1
1
1
0
0
1
1
0
1
1
1
Right
A
FFE
FFF
0-11
X
X
Semaphore free
Left port obtains semaphore
Right side is denied access
Right port is granted access to semaphore
No change. Left port is denied access
Left port obtains semaphore
No port accessing semaphore address
Right port obtains semaphore
No port accessing semaphore
Left port obtains semaphore
No port accessing semaphore
INT
H
X
X
L
R/W
X
X
X
L
CE
X
X
L
L
Status
Right Port
OE
X
X
X
L
CY7C138
CY7C139
A
FFE
FFF
0-11
X
X
INT
X
X
H
L