Visible to Intel only — GUID: rrk1514930092144
Ixiasoft
Visible to Intel only — GUID: rrk1514930092144
Ixiasoft
4.2.1.2.4. Read-During-Write Operation at the Same Address
There are two types of read-during-write operations: same-port operations and mixed-port operations.
- a single-port RAM
- the same port of a true-dual port RAM
- the same port a of simple quad-port RAM
- simple-dual port
- true-dual port
- simple-quad port mode
Intel® FPGA RAM and AMD* Xilinx* RAM support both read-during-write port modes. However, they have different output options. These options vary depending on the operation mode and type of embedded memory block or device that you select.
Intel® FPGA RAMs support configurations with output options of NEW_DATA (flow-through), OLD_DATA, DONT_CARE, or NEW_A_OLD_B. AMD* Xilinx* RAMs support configurations with output options READ_FIRST, WRITE_FIRST, or NO_CHANGE.
Description | Output after Read-During-Write operation | Types of RAM Output | |
---|---|---|---|
AMD* Xilinx* | Intel® FPGA | ||
Output reflects the new data at that address. | New data | WRITE_FIRST | NEW_DATA |
Outputs reflect the old data at that address before the new data is written into memory. | Old data | READ_FIRST | OLD_DATA |
Outputs reflect the previous read data and remains unaffected by the write operation. | Unaffected | NO_CHANGE | Not supported15 |
Read-during-write writes new data into memory, and the output displays unknown values. | Unknown | Not supported | DONT_CARE 16 |
For simple quad port, the read-during-write operation behaves differently for each port:
|
Port A: New data Port B: Old data |
Not supported | NEW_A_OLD_B |
In Intel® FPGA RAMs, the output choices depend on the operation mode and the type of embedded memory block. For information about output choices for same-port and mixed-port read-during-write modes, refer to the Embedded Memory Blocks chapter in the corresponding device handbook.