CY7C024AV/025AV/026AV
CY7C0241AV/0251AV/036AV
Document #: 38-06052 Rev. *H
Page 7 of 19
Table 1. Non-Contending Read/Write
Inputs
Outputs
Operation
CE
R/W
OE
UB
LB
SEM
I/O9–I/O17
I/O0–I/O8
H
X
X
X
X
H
High Z
High Z
Deselected: Power-Down
X
X
X
H
H
H
High Z
High Z
Deselected: Power-Down
L
L
X
L
H
H
Data In
High Z
Write to Upper Byte Only
L
L
X
H
L
H
High Z
Data In
Write to Lower Byte Only
L
L
X
L
L
H
Data In
Data In
Write to Both Bytes
L
H
L
L
H
H
Data Out
High Z
Read Upper Byte Only
L
H
L
H
L
H
High Z
Data Out
Read Lower Byte Only
L
H
L
L
L
H
Data Out
Data Out
Read Both Bytes
X
X
H
X
X
X
High Z
High Z
Outputs Disabled
H
H
L
X
X
L
Data Out
Data Out
Read Data in Semaphore Flag
X
H
L
H
H
L
Data Out
Data Out
Read Data in Semaphore Flag
H
X
X
X
L
Data In
Data In
Write DIN0 into Semaphore Flag
X
X
H
H
L
Data In
Data In
Write DIN0 into Semaphore Flag
L
X
X
L
X
L
Not Allowed
L
X
X
X
L
L
Not Allowed
Table 2. Interrupt Operation Example (assumes BUSYL = BUSYR = HIGH)
[9]
Left Port
Right Port
Function
R/WL
CEL
OEL
A0L–13L
INTL
R/WR
CER
OER
A0R–13R
INTR
Set Right INTR Flag
L
L
X
FFF[12]
XX
X
X
X
L[11]
Reset Right INTR Flag
X
X
X
X
X
X
L
L
FFF (or 1/3FFF)
H[10]
Set Left INTL Flag
XXX
X
L[10]
L
L
X
1FFE (or 1/3FFE)
X
Reset Left INTL Flag
X
L
L
1FFE[12]
H[11]
XX
X
X
X
Table 3. Semaphore Operation Example
Function
I/O0–I/O17 Left I/O0–I/O17 Right
Status
No action
1
1
Semaphore-free
Left port writes 0 to semaphore
0
1
Left Port has semaphore token
Right port writes 0 to semaphore
0
1
No change. Right side has no write access to semaphore
Left port writes 1 to semaphore
1
0
Right port obtains semaphore token
Left port writes 0 to semaphore
1
0
No change. Left port has no write access to semaphore
Right port writes 1 to semaphore
0
1
Left port obtains semaphore token
Left port writes 1 to semaphore
1
1
Semaphore-free
Right port writes 0 to semaphore
1
0
Right port has semaphore token
Right port writes 1 to semaphore
1
1
Semaphore free
Left port writes 0 to semaphore
0
1
Left port has semaphore token
Left port writes 1 to semaphore
1
1
Semaphore-free
Notes:
9.
See Functional Description for specific highest memory locations by device.
10. If BUSYR=L, then no change.
11. If BUSYL=L, then no change.
12. See Functional Description for specific addresses by device.
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