Memory

Memories in computer are electronics components that stores data and program instructions.

            +--------+                 __
           / Register \ 1 Cycle         |
          +------------+                | Primary
         /    Caches    \ ~10           | Storage
        +----------------+              |
       /   Main Memory    \ ~100        |
      +--------------------+           __
     /      Flash Disk      \ ~ 1M      |
    +------------------------+          | Secondary
   /     Traditional Disk     \ ~ 10M   | Storage
  +----------------------------+        |
 /   Remote Secondary Storage   \       |
+--------------------------------+     __

<------- Storage Capacity ------->

Register

It is the fastest memory component, it reads and write in 1 CPU cycle because it is on the CPU, volatile memory.

Caches

Its storage capacity is bigger than Register, but it is slower and it is on the CPU too, volatile memory.

Main Memory (RAM)

Its storage capacity is bigger than Caches, but it is slower than Caches and it is not on the CPU, volatile memory.
Types:

• SRAM: Static RAM
  • It is larger (physical size), consume more power, and smaller in capacity than DRAM.
  • But it is faster
• DRAM: Dynamic RAM
  • it is smaller, and slower than SRAM.
  • But it has more capacity, consume less power.

Flash Disk (ROM)

Its storage capacity is bigger than RAM but slower, and it is non-volatile
Types:

• MROM: Maskable ROM, and can not be programmed
• PROM: Programmable ROM, and can be programmed once.
• EPROM: Erasable PROM, it can be erased using UV and reprogrammed.
• EEPROM: Electrically EPROM, it can be electrically erase and reprogrammed.
• Flash: It is EEPROM with larger page size.

Traditional Disk (HDD)

Its storage capacity is bigger than Flash disk but slower, and it is non-volatile.

Remote Secondary Storage

Its storage capacity is bigger than Traditional disk, but slower, and depends on the network speed.