1. PC COMPONENTS

2. System Unit Cases This is the cabinet that holds the main components of a computer. It includes a plastic front panel for aesthetic purpose. PC have been packaged in a number of different case designs. Each design offer characteristics that adapt to the system to different environment

3. The characteristics for case design include the following Ventilation characteristics Total drive capacity Foot print (amount of desk space the case takes up) Portability Mounting methods for the printed a circuit board

4. PC case designs fall into three basic styles 1. Desktop:- cases style in which the desktop unit sit horizontally on a desktop 2. Towers:- cases are designed to sit vertically on the floor to provide more usable workspace on the desktop. Mini tower & mid towers are short towers designed to take up less vertical space. 3. Portables:- To free users from their desks. These units package the system unit, input units and output unit into a single lightweight package that user can carry.

5. INSIDE THE SYSTEM UNIT The system unit is the basic of any PC system arrangement. The components inside the system unit can be divided into 5 distinct sub units. 1. Switching power supply 2. Disk drives 3. System board 4. Signal cables 5. Options adapter card

6. POWER SUPPLY The component in the system that converts the AC voltage from the commercial power outlet to the DC voltage required by the computer circuitry. It delivers power to the system board and its expansion slot. The form factor (shape& dimension) of the Power supply must much that of the case that it is supposed to go into and the mother board.

7. Figure 1: Power Supply

8. SYSTEM BOARDS It obtains the circuitry that determine the computing power and speed of the entire system it is also referred to as motherboard and planer boards. Types – BTX – Balanced Technology extended ATX – Advanced Technology Extended

9. The Differences Between BTX and ATX Slightly larger than ATX 325x266 divide the PC into zones, hence always the CPU appear in the same zone -designed to place the CPU towards the front of the case for better coiling is more efficient cooling Smaller than BTX 305x244 PC pulls air in through to back into the computer and pushes it directly into microprocessor

10. Figure 2: Motherboard

11. Tutorial Questions What are the differences between BTX and ATX motherboard?

12. Hard disk drives. These are the mainstay of mass data storage in a PC Its capacity is measured in the following units -MB -KB -GB -TB

13. Types of Hard disk 1. ATA (AT Attachment) 2. SCSI (Small Computer System Interface) 3. Fire wire 4. RAID (Redundant Array of inexpensive Disk) 5. Fiber channel

14. ATA PATA (Parallel ATA)  Uses 40-or-80 pins wide ribbon cable to transfer multiple bits simultaneously.  Requires 5volts for transmission.  Cable limit is 18 inches  When two disk are connected together, share the bandwidth Example: IDE Hard Disk SATA ( Serial ATA)  Serial data transfer (I bit at a time)  7 –pin data connection  Cable limit is I meter Only  Only one disk drive per serial so they do not have to share data bandwidth