PC Case

The PC case is a thin sheet metal enclosure that houses the motherboard, power supply and various drives (HDD, FDD, CD, DVD).

• Cases are offered in two styles, desktop and tower. Today the tower type is predominant. It stands upright and is much taller than it is wide. It is usually placed on the floor next to, or under a desk. The desktop has a pizza box profile and usually sits on the desktop.
  
  
• Tower cases are offered in two basic sizes, one that can fit ATX (12" wide) motherboards and one that can accommodate ATX mini (8.5" wide) motherboards. The number of drive bays offered also varies depending on manufacturer.
  
  
• The motherboard and power supply mount to the floor at the rear of the case. The drives (hard, floppy and CD/DVD) mount in enclosures called drive bays at the front of the case.
  
  
• Cases run from $20 to $70 depending on size (ATX or ATX mini), number of drive bays and the wattage of the power supply.

Motherboard

The motherboard is the main circuit board in a PC. It contains all the circuits and components that run the PC.

Major Components found on the motherboard are:

• CPU - the Central Processing Unit is often an Intel Pentium or Celeron processor. It is the heart of every PC. All scheduling, computation and control occurs here.
  
  
• BIOS - Basic Input Output System is a non-volatile memory that contains configuration information about the PC. It contains all the code required for the CPU to communicate with the keyboard, mouse video display, disk drives and communications devices.
  
  When a PC is powered on it uses the BIOS 'boot code' to set up many required functions that bring the PC to a point where it is ready to work.
  
  
• RTC - the Real Time Clock chip keeps date, day and time in a 24 hour format just like your watch. The PC uses this clock to 'time stamp' files as they are created and modified. When you print a file it time stamps the pages as they are printed.
  
  
• Chip Set - these are large chip(s) that integrate many functions that used to be found in separate smaller chips on the motherboard. They save space and cost.
  
  The functions performed by these chip sets often broken into two devices with one providing an interface from the CPU to the memory and the other providing controllers for IDE, ISA, PCI and USB devices (see below).
  
  

Computer hardware is the physical part of a computer, including the digital circuitry, as distinguished from the computer software that executes within the hardware. The hardware of a computer is infrequently changed, in comparison with software and data, which are "soft" in the sense that they are readily created, modified or erased on the computer. Firmware is a special type of software that rarely, if ever, needs to be changed and so is stored on hardware devices such as read-only memory (ROM) where it is not readily changed (and is therefore "firm" rather than just "soft").
specification of a computer

1. Hard Disk
   
2. Mother Board
3. RAM
4. Processor

the above are the most essential parts for the CPU ( central processing unit ). Each of which can be further categorized depending on the quality and quantity.