Computer Hardware Basics Basic Electronics, PC Maintenance, Upgrade and Repair

Computer Types Personal computers typically come in one of three styles . . . . The “desktop.” The original computer, not nearly as popular as it used to be . . . . The “tower.” The choice of most consumers . . . . And the laptop. Portable, convenient, and very difficult to work on.

Hardware - Power Supply The power supply converts the 120VAC from the wall outlet to DC voltage levels used by the various computer components. These voltages are typically 3.3V, 5V and 12V DC. These voltages are used by the motherboard, disk drives, expansion cards, etc.

Hardware - Motherboard A rectangular piece of circuit board covered with many conductors. Called a “computer bus.” This bus provides . . . . Electrical energy paths to the computer components and expansion slots, A way to distribute the digital signals carrying data, control instructions, And small amounts of electrical power to the many different components mounted on the board.

Hardware - Hard Drive Also called the internal drive or hard disk. The location where all computer programs and data are stored. Made up of several disks (often called platters) stacked inside a sealed box. Data and programs are stored on the hard drive as magnetic impulses. It is connected to the power supply by a wire harness made up of several different colored wires

Hardware - Hard Drive Data is transmitted to and from the hard drive through a flat parallel ribbon cable connected between the drive and the motherboard. Newer systems of today are using smaller serial cables to perform this function.

Hardware - CPU Acronym for “Central Processing Unit.” It is the microprocessor and the brain of the computer. Contains millions of microscopic electronic components called transistors. The transistors are electrically connected in such a way that they can interact with computer programs and process data.

Hardware - CPU The CPU controls the data in the computer. Commands are issued to the CPU via software and it translates the commands into actions. The CPU does not think or possess human intelligence. It simply carries out the program codes written in the software program.

Hardware - RAM Acronym for “Random Access Memory.” It is the location where computer programs are loaded from the hard drive. Is classified as volatile memory, which means that the data and programs loaded in it are lost when computer power is turned off. Usually mounted in several parallel slots on the motherboard.

Hardware - RAM RAM is a place where data is temporarily stored. It is emptied when the computer turns off. When the PC is turned back on, new information is loaded into the RAM.

Hardware - BIOS and CMOS BIOS is acronym for “Basic Input/Output System. Stored in a special kind of memory chip called an EEPROM, formerly just a PROM. Consists of software programs that support the compatibility between the CPU and devices like the hard drive, CD-ROM drive and the monitor. BIOS can be updated by “flashing” the EEPROM with the updated BIOS program.

Hardware - BIOS and CMOS CMOS is an acronym for “complimentary metal oxide semiconductor”, which describes the electronic technology to construct the chip (integrated circuit). BIOS setup information is stored in the CMOS chip. Information such as the date and time, as well as information about the computer’s hardware. A battery on the motherboard is used to hold the information in CMOS even after the computer is turned off.

Hardware - Expansion Cards Network Card Video Audio Card Card Expansion cards are often called interface cards or host adapters. They allow the computer to be custom-designed to meet the needs of different consumers. It may allow upgrade from a less capable motherboard integrated circuitry. The expansion cards fit into slots on the motherboard. Typical types of slots are ISA, EISA, and PCI. Video Card Network Card Audio Card

Hardware - Cooling Fans Cooling fans provide a constant stream of air across the computer components. The typical CPU comes with a fan mounted directly on top of it to assist in the cooling process. Heat KILLS! Electronic components are damaged or destroyed by excessive heat.

Hardware - Cables Cables connect all of the computer systems together. There are many different types of cables inside a PC. Flat ribbon cables are used to connect the motherboard to the hard drive, CD-ROM drive and floppy drive. Flat ribbon cables consist of many parallel conductors covered in insulation. Today’s hard disk drives use SATA cables instead of parallel ribbon cables.

Hardware - Cables Higher levels of electrical power can’t run through ribbon cable. Therefore, separate wiring harnesses from the power supply are used. There are also a lot of external cables used to connect various peripheral devices.

Hardware - Other Devices Floppy Drives – a floppy drive reads and writes to a 1.44MB magnetic floppy disk. It stores small amounts of data. CD-ROM Drive – (Compact Disk Read Only Memory Drive) A drive that can read large amounts of data from a CD-ROM using a laser beam of light. DVD Drive – (Digital Versatile Disk Drive) A drive that reads data from a DVD using a laser beam of light. DVD offers the highest storage capacity of all laser-based CD’s thus far.

Electrostatic Discharge Abbreviated “ESD”, is best defined in the world of computer maintenance as the transfer of static electrical energy from one object to another. Usually created by friction. When two dissimilar materials are rubbed together, an electric charge is produced. Integrated circuits (IC’s) in a computer are very small, and made of material that is very susceptible to ESD. The electrostatic discharge will damage (destroy) the IC.

Electrostatic Discharge To avoid ESD, technicians wear a ground strap when handling static sensitive devices. The anti-static wrist strap bleeds off any static charge buildup on a technician’s body and sends it to ground.. Also, when working with static sensitive material outside of the PC case, a static “mat” should be used. It works similarly to the wrist strap.