What is a computer?

1. What is a computer? A personal computer (PC) is a computing device that is made up of many distinct electronic components that all function together in order to accomplish some useful task.

2. Identifying components of a mother board. • The spine of the computer is the motherboard otherwise known as the system board, planar board or main board. It is the most important component in the computer because it connects all other components of a pc together. On the system board you will find: Central Processing Unit slot, Expansion slots, Video slots, Random access memory (RAM) slots and a variety of other components.

3. TYPES OF SYSTEM BOARDS • Nonintegrated- each major assembly (PART) is installed in the computer as an expansion card. Nonintegrated boards can be easily indentified because each expansion slot is usually occupied by one of these components eg video card, mouse and keyboard connectors. • Integrated- unlike the nonintegrated board most of the components are built onto the board leaving the expansion slots empty.

4. SYSTEM BOARD FORM FACTORS (DESIGN) • System boards are also classified by their form factor or design. • Advanced Technology Extended (ATX) • Micro ATX • New Low-Profile Extended (NLX) • Balanced Technology Extended (BTX)

5. SYSTEM BOARD COMPONENTS • CHIPSETS • EXPANSION SLOTS • MEMORY SLOTS • CPU SLOTS OR SOCKETS • POWER CONNECTORS • ONBOARD DISK DRIVE CONNECTORS • KEYBOARD AND MOUSE CONNECTORS • BIOS • CMOS • FIRMWARE • BUS

6. CHIPSETS • A chipset is a collection of chips or circuits that perform interface and peripheral functions for the processor. This collection of chips is usually the circuitry that provides interfaces for memory, expansion cards and onboard devices and generally dictates how the motherboard will communicate with the installed components. • Northbridge- manage high speed peripheral communications. Responsible for communications with integrated video using AGP and PCIE also the CPU to memory communication. • Southbridge- responsible for providing support to slower devices such as PS/2, Parallel,IDE etc.

7. EXPANSION SLOTS • The most visible parts of any mother board are the expand slots. Usually 1-6 inches long and approximately ½ inch wide. As the name suggests these slots are used to install various devices in the computer to expand its capabilities. Each type is different in appearance and functions. • PCI • AGP • PCIE • AMR • CNR

8. PERIPHERAL COMPONENT INTERCONNECT (PCI) • This slot is 32bit and are easily recognised usually 3 inches long, white or blue in colour (colour may vary) PCI slots can be found in any computer that has a pentium class processor or higher. Usually 3.3 or 5V. PCI slots are used to install devices such as dial up modems, network card, sound card etc.

9. ACCELERATED GRAPHICS PORT (AGP) • Are known for video card use. • AGP slots were designed to be a direct connection between the video circuitry and the PC’S memory. • Usually brown and located right next to the PCI slots on the motherboard and are slightly shorter than the PCI slots.

10. PERIPHERAL COMPONENT INTERCONNECT express(PCIe) • A newer expansion slot architecture that is being used by mother boards. • It was designed to replace AGP and PCI. • It has the capability of being faster than AGP while maintaining the flexibility of PCI. • Motherboards with PCIe slots may have regular PCI slots for backward compatibility with PCI. • Seven different types of PCIe • X1 X2 X4 X8 X12 X16 and X32. • X1 X4 and X16 is the most common.

11. AUDIO MODEM RISER (AMR) • The manufacturers develop a way of separating the analog circuitry, for example, modem and analog audio, onto it’s own expansion card. • This slot is slowly becoming obsolete.

12. COMMUNICATIONS AND NETWORKING RISER (CNR) • A slot found on certain PC motherboards and used for specialized networking, audio, and telephony equipment. A motherboard manufacturer can choose to provide audio, networking, or modem functionality in any combination on a CNR card. CNR slots were once commonly found on Pentium 4-class motherboards, but have since been phased out in favor of on-board or embedded components.

13. SIMM (single in-line memory modules)and DIMM(dual in-line memory module) Memory Modules • The available memory on your PC will dramatically effect the speed at which your computer works. • SIMM's, come in 30 and 72 pin sizes the latter now becoming the standard. If you are using a 486 motherboard you may well find that you have four 30 pin and two 72 pin sockets. Older boards used 30 pin sockets. • Generally, the 30 pin SIMM module was designed for 8-bit data flow, and are generally placed in groups of four to give a 32-bit data path. (4x8 = 32). This would mean that with 32 bit operation would be 4, 30 pin SIMM's at a time. Thus the 72 pin SIMM was designed for 32-pin operation, reducing the number of sockets required although this had to be off-set with a 50% increase in physical length. • To handle 64-bit operation the 72 pin SIMM would need to 'pair-up', once again, causing a space problem once more on the motherboard. One answer was the DIMM(dual in-line memory module). • Most Pentium motherboard now incorporate two, or more slots,  for a 168 pinn DIMM   module. DIMMs look similar to the older SIMM but differ in a key area. The   DIMM module uses both sides of the chip with 168 pin version having 84 pins on each side. Each pin is completely independent of the others, and makes a separate electrical contact. The density of the DIMM memory module is increased with only the slightest increase in the module’s physical size. • DIMM's also fit differently into the slot. The DIMM module is slid into 'channels' on the two edges of the socket. They are then pressed into the socket until they 'click' home.

14. SIMM MEMORY SLOT

15. DIMM MEMORY SLOT

16. TYPES OF RANDOM ACCESS MEMORY (RAM) • Synchronous Dynamic Random Access memory (SDRAM) • SDR-SDRAM- Single Data Rate • DDR –SDRAM- Double Data Rate

17. A Few Differences between SDRRAM AND DDRSDRAM. • SDRAM stands for Synchronous Dynamic Random Access Memory. DDR is short for "DDR SDRAM" and stands for Double Data Rate. Nowadays to avoid misunderstandings SDRAM is often specified as SDR SDRAM and SDR stands for Single Data Rate by analogy with DDR. Therefore, the main difference between SDR and DDR memory the doubled speed: DDR can transfer data at roughly twice the speed of SDRAM. For example, PC133 SDRAM runs at 133 MHZ, while 133 MHZ DDR effectively runs at 133 MHZ x 2 = 266 MHZ. SDRAM has 168 pins and two notches at the connector, which prevents it from being used in a DDR SDRAM motherboard and vice versa. It comes mainly in PC66, PC100 and PC133; the bus speeds of the RAM in MHz.DDR SDRAM has 184 pins and a single notch at the connector. It comes in speeds of PC1600 (166 MHz), PC1800 (200 MHz), PC2100 (266 MHz), PC2700 (333 MHz), PC3200 (400 MHz), and PC4400 (550 MHZ). The numbers represent the theoretical maximum bandwidth of the DDR SDRAM in Megabytes per second (MB/s). For example, PC2100 has a theoretical maximum bandwidth of 2100 MB/s.

18. SDR-SDRAM (To identify SDR-SDRAM look for the two cut-out on the memory module.)

19. DDR SDRAM (To identify DDR SDRAM look for the one cut-out on the memory module.)

20. SDR-SDRAM AND DDR-SDRAM

21. CENTRAL PROCESSING UNIT (CPU) • The central processing unit (CPU) or the “brain” is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. The central processing unit carries out each instruction of the program in sequence, to perform the basic arithmetical, logical, and input/output operations of the system. This term has been in use in the computer industry at least since the early 1960s.[1] The form, design and implementation of CPUs have changed dramatically since the earliest examples, but their fundamental operation remains much the same.

22. Die of an Intel 80486DX2 microprocessor (actual size: 12×6.75 mm) in its packaging. (Magnified many times)

23. The die from an Intel 8742

24. Intel 80486DX2 microprocessor in a ceramic PGA package.

25. Pentium 4 CPU in housing

26. CPU SOCKET AND SLOT • A CPU socket or CPU slot is a mechanical component that provides mechanical and electrical connections between the CPU and motherboard. This allows the CPU to be replaced without risking the damage of the CPU. When replacing or taking the CPU out of the socket or slot one should be very careful. • Common sockets utilize retention clips that are designed to apply a constant force, which must be overcome when a device is inserted. For chips that sport a high number of pinouts, either zero-insertion force (ZIF) sockets or land grid array (LGA) sockets are used instead. These designs apply a compression force once either a handle (for ZIF type) or a surface plate (LGA type) is put into place. This provides superior mechanical retention while avoiding the added risk of bending pins when inserting the chip into the socket. • CPU sockets are used in desktop and server computers (laptops typically use surface mount CPUs). Because they allow easy swapping of components.

27. The Socket 370 processor socket, a ZIF type PIN GRID ARRAY-PGA socket

28. Socket A (also known as Socket 462

29. MOTHERBOARD WITH TWO CPU SOCKETS

30. THINGS TO REMEMBER • Slots and sockets are not universal i.e no one Socket or slot can accommodate any type of CPU. • CPUs are made for a specific slot or socket so be careful when choosing a motherboard and CPU. • CPU speeds are calculated in MHZ and GHZ. • MHZ= Millions of cycles per second. • GHZ= Billions of cycles per second.

31. SLOT TYPE CPU

32. SLOT TYPE CPU

33. POWER CONNECTOR • ALLOWS THE MOTHERBOARD TO BE CONNECTED TO THE POWER SUPPLY IN ORDER TO RECEIVE POWER.

34. ATX POWER CONNECTOR (Advance Technology Extended)

35. OLDER VERSION (AT)

36. ONBOARD DISK DRIVE CONNECTORS • Almost every computer made today uses some type of disk drives to store data and programs until they are needed. All drives need some form of connection to the motherboard in order for the computer to communicate with the disk drives. These connections are known as “drive interfaces” • Floppy Drive Interface • Hard Disk Drive Interface

37. FLOPPY DRIVE INTERFACE(34 PINS)

38. HARD DISK DRIVE INTERFACE(40 PINS)

39. KEYBOARD AND MOUSE CONNECTORS • Purple – Keyboard • Green- Mouse

40. BIOS • Basic Input/Output System • Aside from the CPU it’s the most important chip. • Contains the BIOS system software that boots the Pc and allows the operating system to interact with the installed hardware. • A major function of the BIOS is to perform a process known as Power On Self Test (POST). • POST is a series of system test perform by the system BIOS. • POST routine verifies the integrity of the BIOS itself.

41. CMOS • COMPLEMENTARY METAL- OXIDE SEMI-CONDUCTOR. • Keeps settings of the PC when power is off and cord unplugged which includes: • Date, Time, Hard Drive Config, Memory, Integrated ports, Boot Sequence and Power management. • To prevent CMOS from loosing its rather important information, motherboard manufacturers include a small battery called the CMOS battery to power the CMOS memory.

42. FIRMWARE • FIRMWARE IS THE NAME GIVEN TO ANY SOFTWARE THAT IS ENCODED IN HARDWARE, USUALLY A READ ONLY MEMORY (ROM) CHIP. THE BEST EXAMPLE OF FIRMWARE IS THE BIOS ROUTINE, WHICH IS BURNED(ENCODED) IN TO A CHIP.

43. BUS • A BUS IN THIS SENSE IS A COMMON COLLECTION OF SIGNAL PATH WAYS OVER WHICH RELATED DEVICES COMMUNICATE WITHIN THE COMPUTER SYSTEM. • EXPANSION BUSES OF VARIOUS ARCHITECTURES, SUCH AS PCI AND AGP, INCORPORATE SLOTS AT CERTAIN POINTS IN THE BUS TO ALLOW INSERTION OF EXTERNAL DEVICES. • OTHER BUSES EXIST WITHIN THE SYSTEM TO ALLOW COMMUNICATION BETWEEN THE CPU AND OTHER DEVICES WITH WHICH DATA MUST BE EXCHANGED.