Many computer users will be familiar with RAM.
You might not know that the RAM youre thinking of is a key in of DRAM.
your machine also has some SRAM in it too.
SRAM is significantly more expensive but much faster.
This gives rise to their two different uses.
DRAM is used as the main system RAM.
The low cost and high density are helpful because you need gigabytes of it in modern computers.
SRAM is used as the CPU cache.
The differences above, however, dont really explain why one is considered static and the other dynamic.
The difference is actually in how the memory cell works.
Static RAM simply needs to be written to.
A DRAM cell is recharged by reading its contents and then writing back the same data.
Note:Both DRAM and SRAM are volatile memory.
Both will lose any data they hold if they lose power.
This is also true of PSDRAM.
This would be entirely unnecessary and confusing to users.
Which adds to the load on the memory controller.
SRAM doesnt have to do any of this.
Each SRAM cell doesnt suffer from charge decay, so the cell never needs to be refreshed.
The Best of Both Worlds?
While it is relatively inexpensive, the density is lower than true DRAM.
This is because PSDRAM introduces extra internal circuitry that automatically refreshes the memory cells.
Like SRAM, the memory controller doesnt need to do anything to keep data in PSDRAM.
The simplification means that the command circuitry needed to interact with PSDRAM is less complicated than DRAM.
This specific issue means that there may be unexpectedly high memory latency in some cases.
Conclusion
PSDRAM is a middle ground between DRAM and SRAM.
Memory cells need to be refreshed regularly because theyre built on the same process as DRAM.
At the end of the day, though, PSDRAM doesnt offer many particular benefits.
It is not used in standard computers at all.
