The following waveforms show the behavior of altsyncram megafunction for the chosen set of parameters in design reg_ram.v. For the purpose of this simulation, the contents of the memory at the start of the sample waveforms is assumed to be ( FFFFFFF0, FFFFFFF1, FFFFFFF2, FFFFFFF3, ...). The design reg_ram.v has one read port and one write port. The read port has 32 words of 32 bits each and the write port has 32 words of 32 bits each. The output of the read port is unregistered.
The above waveform shows the behavior of the design under normal read conditions. The read happens at the rising edge of the enabled clock cycle. The output from the RAM is undefined until after the first rising edge of the read clock. The clock enable on the read side input registers are disabled. The clock enable on the output registers are disabled.
The above waveform shows the behavior of the design under normal write conditions. The write cycle is assumed to be from the rising edge of the enabled clock in which wren is high till the rising edge of the next clock cycle. In DUAL_PORT mode, when the write happens at the same address as the one being read in the other port, the read output is unknown. Actual write into the RAM happens at the falling edge of the write clock. The clock enable on the write side input registers are disabled. The clock enable on the output registers are disabled.