Why does the Intel® Stratix® 10 Single Port RAM show Don’t care value instead of Old data for read during write?

Description

Due to a problem in the Intel® Quartus® Prime Pro Edition Software version 17.1 and earlier, you will see incorrect behavior in simulation for read during write to an Intel® Stratix® 10 FPGA single-port RAM with the following parameters settings:

altera_syncram_component.intended_device_family  = "Stratix 10"

altera_syncram_component.operation_mode  = "SINGLE_PORT"

altera_syncram_component.read_during_write_mode_port_a  = "OLD_DATA"

altera_syncram_component.ram_block_type  = "M20K"

This is only a simulation issue, you will not see this on hardware.

Resolution

To work around this problem, run the post-synthesis or post-fit netlist simulation instead of functional simulation.

This problem is fixed starting with the Intel® Quartus® Prime Pro Edition Software version 18.1.1.