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Guideline: Implement External Conflict Resolution
In the true dual-port RAM mode, you can perform two write operations to the same memory location.
However, the memory blocks do not have internal conflict resolution circuitry. To avoid unknown data
being written to the address, implement external conflict resolution logic to the memory block.
Guideline: Customize Read-During-Write Behavior
Customize the read-during-write behavior of the memory blocks to suit your design requirements.
Figure 2-1: Read-During-Write Data Flow
This figure shows the difference between the two types of read-during-write operations available—same
port and mixed port.
Port A
data in
Port B
data in
Port A
data out
Port B
data out
Mixed-port
data flow
Same-port
data flow
FPGA Device
Same-Port Read-During-Write Mode
The same-port read-during-write mode applies to a single-port RAM or the same port of a true dual-port
RAM.
Table 2-2: Output Modes for Embedded Memory Blocks in Same-Port Read-During-Write Mode
This table lists the available output modes if you select the embedded memory blocks in the same-port
read-during-write mode.
Description
Memory Type
Output Mode
The new data is available on the rising edge of
the same clock cycle on which the new data is
written.
M10K
"new data"
(flow-through)
The RAM outputs "don't care" values for a
read-during-write operation.
M10K, MLAB
"don't care"
Altera Corporation
Embedded Memory Blocks in Cyclone V Devices
2-3
Guideline: Implement External Conflict Resolution
CV-52002
2013.05.06