TYPES OF MEMORY AND HDD

                                      MEMORIES ARE OF TWO TYPES 

1. VOLATILE MEMORY             - IT IS ALSO 
    CALLED TEMPORARY MEMORY.
2. NON VOLATILE MEMORY   - IT IS ALSO 
   CALLED PERMANENT MEMORY. 

                              MEMORYIES ARE OF ANOTHER  TWO TYPES

1. PRIMARY MEMORY          - RAM , ROM
2. SECONDARY MEMORY   - HARD DISK , FLOPPY DISK , DVD/CD.

                               TYPES OF HARD DISK BASED ON CONNECTORS 

1. I.D.E        - INTEGRATED DRIVE ELECTRONICS 
2. P.A.T.A   - PARALLEL ADVANCE TECHNOLOGY ATTACHMENT 
3. S.A.T.A   - SERIAL ADVANCE TECHNOLOGY ATTACHMENT 
4. S.C.S.I    - SMALL SYSTEM COMPUTER INTERFACE 

                                         I.D.E HARD DISK ARE OF TWO TYPES : 
1. CABLE 40 
2. CABLE 80

                                         DIFFERENCE BETWEEN

                 I.D.E POWER CONNECTOR & S.A.T.A POWER CABLE 

1. I.D.E IS A MOLE X CONNECTOR WHERE AS S.A.T.A IS A POWER CONNECTOR
2. I.D.E HAS 4 PINS WHERE AS S.A.T.A HAS 15 PINS

•    NO OF PINS IN S.C.S.I HARD DISK ARE 50 PINS, 68 PINS OR 80 PINS
•    FIRST HARD DISK WAS SHIPPED BY IBM IN RAM AC 305