Cyclone II Memory Blocks
Figure 8–22. Cyclone II Same-Port Read-During-Write Functionality Note (1)
inclock
A
A
B
data
wren
q
Old
Note to Figure 8–22:
(1) Outputs are not registered.
Mixed-Port Read-During-Write Mode
This mode applies to a RAM in simple or true dual-port mode, which has
one port reading and the other port writing to the same address location
with the same clock.
In this mode, you also have two output choices: old data or don't care. In
Old Data Mode, a read-during-write operation to different ports causes
the RAM outputs to reflect the old data at that address location. In Don't
Care Mode, the same operation results in a "don't care" or unknown value
on the RAM outputs.
Figure 8–23. Cyclone II Mixed-Port Read-During-Write: Old Data Mode
Note (1)
inclock
address_a and
address_b
Address Q
B
data_a
A
wren_a
wren_b
q_b
Old
A
B
Note to Figure 8–23:
(1) Outputs are not registered.
Altera Corporation
February 2008
8–29
Cyclone II Device Handbook, Volume 1
ALTERA [ ALTERA CORPORATION ]
