Memory

Memory

1. Random Access Memory (RAM)

   • RAM is volatile which means the data stored in the RAM is lost when there is no power.
   • RAM is very fast, which allows the CPU and Cache to access data quickly without having to access the secondary storage which is much slower.
   • The data is random because each memory location can be accessed in any order - making it random.

2. Read Only Memory (ROM)

   • ROM is located on the motherboard and stores the BIOS and boot up routine.
   • Unlike RAM, the data stored in ROM is kept when there is no power.
   • The Bootstrap Loader is located here which loads the OS

3. Types of Memory

   • Static Random Access Memory (SRAM)
     • Advantages
       • Can be Non-Volatile when used for Flash Memory
       • It is very fast, much faster than DRAM
       • Very Reliable and a Low Power Consumption
     • Disadvantages
       • It is very expensive per MB.
       • It has a very low capacity
     • It uses a group of transistors combined for each bit of data.
   • Dynamic Random Access Memory (DRAM)
     • It uses a transistor and a capacitor to represent and store data
     • Advantages
       • It is much cheaper compared to SRAM
       • It comes in much higher capacity than SRAM
     • Disadvantages
       • It is volatile so stored data is lost when there is no power.
       • It requires a memory refresh circuit to prevent data loss, this makes it Dynamic.

4. Other Types of Memory

   • Virtual Memory
     • When there is no more RAM storage left, the computer uses virtual memory.
       • The amount of secondary storage assigned can be changed in the OS.
     • Virtual Memory is assigning a small amount of secondary storage to act as main memory.
       • This is very very slow, therefore it is not ideal.
   • Flash Memory
     • This is ROM but can be programmed by forcing large amounts of electrical current through it.
     • A USB stick is an example of this.