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The Visible PC. Chapter 1. Central Processing Unit (CPU). also called “microprocessor” performs all the calculations that take place inside a PC have a cooling fan have a make and model Intel Pentium / AMD Athlon, etc. CPU’s (continued).
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The Visible PC Chapter 1
Central Processing Unit (CPU) • also called “microprocessor” • performs all the calculations that take place inside a PC • have a cooling fan • have a make and model • Intel Pentium / AMD Athlon, etc.
CPU’s (continued) • measure potential performance with a clock speed measured in megahertz • first CPU - 4.77 MHz • today CPU - 1000 MHz = 1GHz • come in different packages • Pin Grid Array (PGA) * most common • Single Edge Cartridge (SEC)
Random Access Memory (RAM) • stores programs and data currently being used by the CPU • measured in units called bytes or megabytes • average PC will have from 32 - 128 MB • DIMM’s and SIMM’s • Dual Inline Memory Module • most common today - 168 pin • Single Inline Memory Module • basically obsolete
RAM (continued) • 2 most common sizes of SIMM’s • 30 pin and 72 pin • 3 most common sizes of DIMM’s • 168 pin • 2 Small Outline DIMM’s 72 and 144 pin (used for laptops mostly)
Motherboard • “chassis of an automobile” • everything connects directly or indirectly to it • thin, flat piece of circuit board • contains sockets and connectors for various components of the PC • use tiny wires called “traces” to connect the various components
Motherboard (continued) • use multipurpose expansion slots to add optional components • expansion cards plug into the expansion slots
Power Supply • provides the necessary electrical power • takes 110-volt AC power and converts it into 12-volt, 5-volt, and 3.3-volt DC power
Floppy Drives • two types of floppy drives • 3.5 inch (common) / 5.25 inch (old) • connects via a 34-pin ribbon cable • floppy cables are unique in 2 ways • narrowest ribbon cable (approx. 1.5 in. wide) • has a twist in the middle • they need power so they have a connector which attaches to the power supply
Hard Drive • store programs and data that are not currently being used • capacity measured in megabytes like RAM • cap. can vary from 500 MB - 75 GB • average PC will have 1 HD but can accept up to 4
Hard Drives (continued) • 2 common types of HD’s • EIDE and SCSI • 95% of PC’s use EIDE although both can coexist in one • EIDE - 40 pin, 2 in. cable • SCSI - 50 pin, 2.5 in. cable • SCSI can connect many different devices and will be discussed in detail later
CD-ROM Drive • used to have their own special controllers • now they run on EIDE or SCSI controllers • most PC’s have an EIDE hard drive and a EIDE CD-ROM Drive on one controller
Connectors • although PC’s use 50 different connectors, almost all connectors fit into one of seven major types: • DB - BNC • DIN - audio • Centronics - USB • RJ
Connectors • DB Connectors • have a slight “D” shape • can have from 9 to 37 pins, but rarely more than 25 • can be male/female • DIN Connectors • 2 sizes: DIN and mini-DIN • always female
Connectors • Centronics • also “D” shaped, but have a large central tab and contacts instead of pins • have wings to lock in place • rarely see in back of PC, but almost every printer in existence has 36-pin socket • RJ Connectors • RJ-11 - used for modems • RJ-45 - used for network cabling
Connectors • BNC Connectors • commonly referred to as coax connector • slowly fading, most PC’s use RJ-45 now • similar to the connection on back of your TV • Audio Connectors • used exclusively on sound cards and are exactly like the plug for headphones on a walkman
Connectors • Universal Serial Bus (USB) Connectors • distinctive rectangular shape • devices are hot-swappable • allows you to daisy-chain up to 127 devices • FireWire Connectors • also known as IEEE 1394 • moves data at incredibly high speeds making popular for streaming video
Sound Cards • perform 2 functions • take digital information and turn it into sound • take sound that is input and turn it into digital • all sound cards have jacks for speakers and a microphone, and a line-in and line-out • most provide a 15 pin DB socket that enables you to attach an instrument or joystick • also can connect to CD-ROM
Video and Network Cards • Video Cards • 15-pin female DB connector, 3 rows of pins • nothing else like it on the back of PC • Network Cards • will have one or more of the following types of connectors: RJ-45, BNC, 15-pin 2 row female DB, or 9-pin fem. DB
Keyboard / Mouse / Modem • Keyboard • 2 main types AT DIN and PS/2 style mini DIN • Mouse • 2 sizes: 25-pin (older) / 9-pin (most common) • many PC’s use USB for the mouse so there’s not excessive cable lying around in the PC • Modem • external and internal • have 2 RJ-11 sockets
Printer / Joystick • Printer • Use a parallel port as opposed to serial • use a 25-pin female DB connector • Joystick • use a 15-pin female DB connector • originally used as a mouse, now just used for games
Jumpers and Switches • Jumpers - tiny pins, usually half a centimeter long • shunts connect pins to create a circuit • jumpers without a shunt - open or off • jumpers with a shunt - closed or on • if a shunt is on only one pin and not connecting it is considered parked
Jumpers and Switches • Switches • same thing as jumpers but you don’t have to worry about losing the shunts • use a small screwdriver or a mechanical pen to flip the switches, not a pencil or pen • there is no industry standard for jumpers and switches so you must read the documentation on the particular PC to know which one is which