Primary Memory : Types and differences from Secondary Storage Memory

Computer memory are of two types primary and secondary.
This video covers all about primary memory and secondary memory and differences between them in English.
Primary memory types includes RAM means Random Access Memory and ROM means Read Only Memory.
While Secondary storage includes HDD means Hard disk drives, Floppy disks, CD, DVDs etc.
This video also explains the Different types of RAM like SRAM, DRAM which stands for Static RAM and Dynamic RAM and also DDR SDRAM.
Computer permanent memory ROM also are of different types like Masked ROM, PROM, EPROM, EEPROM explained in detail.
And also how CPU uses these types of memory starting from its Register memory, cache memory and then main memory or RAM.