4. THE INPUT UNIT IS RESPONSIBLE FOR ACEEPTING INPUT i.e., DATA INSTRUCTIONS FROM THE USER.THIS WORK IS ACCOMPLISHED WITH THE HELP OF INPUT DEVICES. EXAMPLE:-KEYBOARD,MOUSE, MICROPHONE etc.

6. THE MOUSE IS POINTING DEVICE WITH A ROLLER ON ITS BASE. MOUSE CONTROLS MOVEMENT OF POINTER ON SCREEN. WHEN A MOUSE MOVES ON A FLAT SURFACE, THE CURSOR ON THE SCREEN ALSO MOVES IN THE DIRECTION OF MOUSE’S MOVEMENT. MOUSE GENERALLY HAS TWO OR THREE BUTTONS AND IT MAY OR MAY NOT HAVE A WHEEL. THE MOUSE IS POINTING DEVICE WITH A ROLLER ON ITS BASE. MOUSE CONTROLS MOVEMENT OF POINTER ON SCREEN. WHEN A MOUSE MOVES ON A FLAT SURFACE, THE CURSOR ON THE SCREEN ALSO MOVES IN THE DIRECTION OF MOUSE’S MOVEMENT. MOUSE GENERALLY HAS TWO OR THREE BUTTONS AND IT MAY OR MAY NOT HAVE A WHEEL.

11. IMPACT PRINTERS :- IN THESE PRINTERS, THERE IS A MECHANICAL CONTACT BETWEEN THE PRINT HEAD AND PAPER. EXAMPLE :- NON IMPACT PRINTERS :- IN THESE PRINTERS, THERE IS NO MECHANICAL CONTACT BETWEEN THE PRINT HEAD AND PAPER. EXAMPLE :-

13. MEMORY DEVICES SECONDARY MEMORY PRIMARY MEMORY

14. RAM ROM PRIMARY MEMORY FLOPPY DISKHARD DISK COMPACT DISKDIGITAL VIDEO DISK SECONDARY MEMORY PRIMARY MEMORY:- IT IS A VOLATILE MEMORY. SECONDARY MEMORY:- IT IS A NON VOLATILE MEMORY.

17. THE CACHE MEMORY IS A HIGH SPEED MEMORY AVAILABLE INSIDE CPU IN ORDER TO SPEED UP ACCESS TO THE DATA AND INSTRUCTIONS STORED IN RAM MEMORY. TWO TYPES OF CACHE MEMORY ARE:- 1.LEVEL 1 { L1 } CACHE ;- BUILT INSIDE THE CPU 2. LEVEL 2 { L2 } CACHE :- EXTERNAL TO THE CPU AND RESIDES ON THE MOTHERBOARD