DualPortRAM:

The difference between single port RAM and dual port RAM is that single port RAM can be accessed at one address at one time, thus you can read/write only one memory cell during each clock cycle. Dual port RAM has ability to simultaneously read and write different memory cells at different addresses.
SPRAM uses a 6 transistor basic ram cell, while the dual port ram cell uses 8 transistor cell for memory.
so the area of spram is much smaller than the area of dpram cell. To gain the advantages of both spram (less area) and dpram ( high speed) Pseudo dual port ram is introduced. which can read and write the data in the same clock, using rising and falling edges for the operations respectively, and using spram memory cell for the storage of data.