CY7C144, CY7C145
Document #: 38-06034 Rev. *E
Page 5 of 20
Table 3. Non-Contending Read/Write
Inputs
Outputs
Operation
CE
R/W
OE
SEM
I/O0−7/8
H
X
X
H
High Z
Power Down
H
H
L
L
Data Out
Read Data in Semaphore
X
X
H
X
High Z
I/O Lines Disabled
H
X
L
Data In
Write to Semaphore
L
H
L
H
Data Out
Read
LL
X
H
Data In
Write
L
X
X
L
Illegal Condition
Table 4. Interrupt Operation Example (assumes BUSYL = BUSYR = HIGH)
Function
Left Port
Right Port
R/W
CE
OE
A0−12
INT
R/W
CE
OE
A0−12
INT
Set Left INT
XX
X
X
L
L
L
X
1FFE
X
Reset Left INT
XL
L
1FFE
H
X
L
L
X
X
Set Right INT
L
L
X
1FFF
X
XXX
X
L
Reset Right INT
X
X
X
XXX
L
L
1FFF
H
Table 5. Semaphore Operation Example
Function
I/O0-7/8 Left
I/O0-7/8 Right
Status
No action
1
1
Semaphore free
Left port writes semaphore
0
1
Left port obtains semaphore
Right port writes 0 to semaphore
0
1
Right side is denied access
Left port writes 1 to semaphore
1
0
Right port is granted access to semaphore
Left port writes 0 to semaphore
1
0
No change. Left port is denied access
Right port writes 1 to semaphore
0
1
Left port obtains semaphore
Left port writes 1 to semaphore
1
1
No port accessing semaphore address
Right port writes 0 to semaphore
1
0
Right port obtains semaphore
Right port writes 1 to semaphore
1
1
No port accessing semaphore
Left port writes 0 to semaphore
0
1
Left port obtains semaphore
Left port writes 1 to semaphore
1
1
No port accessing semaphore
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