We have a lot to cover! We will not go into great detail Basics of operation of CPU, Motherboard, Buses Survey of Slots and Ports Enough to tie our picture together
The Processor The heart of the computer is the processor CPU, for Central Processing Unit Very complicated beasts! We will summarize its function
The CPU Performs all instructions in programs Processes information Does all math, comparison, etc. Info goes in, info comes out! The ALU (Arithmetic and Logic Unit) performs these tasks Controls other devices in the system Includes a small amount of built-in memory To store the data it is currently using ‘Registers’ and ‘Cache’
In the System Processor (CPU) InputOutput Storage
CPUs: Different packages
CPUs: Things to notice See all of the pins sticking out? These are the wires that connect it to the outside world Wires means information in and out
How a CPU plugs into the computer Plugs into the ‘Motherboard’ The pins all plug into a socket What is a motherboard?
Motherboards We’ve talked about how all information in a computer passes over ‘wires’ Electrical current! There are lots of components to connect! If we just used WIRES, it would look like spaghetti!
Motherboard Rather than dealing with spaghetti, a system has been developed where one component contains ALL of the wiring Well, almost all… The wiring is all done with printed circuits No wires dangling! Every other component plugs into this component, to be connected to the others
Motherboard This component is the Motherboard (or Mainboard) Motherboard provides wiring to connect components All components plug into motherboard Motherboard also controls things like timing Don’t worry too much about this
Memory We know that the computer needs Memory Stores the programs and data currently in use RAM: Random Access Memory
RAM RAM comes in chips called DIMMS (now) RAM works very simply… Every bit is represented by a CAPACITOR A capacitor can store an electrical charge (sort of like a battery…) Store a bit: Store the electrical charge (on or off) Read a bit: Test to see if there is a charge or not Don’t worry about any more detail than that!
RAM comes in many sizes, speeds RAM keeps evolving, to become bigger and faster Typical modules today are 128M, 256M, 512M There is a list of terms on page 107 Latest types DDR- Like SDRAM, but faster Rambus- Faster still, but expensive!
What RAM looks like Long, thin chips Inserted in motherboard in rows
How RAM connect to motherboard Notice the markings on the board?
Buses We pause for a moment, and talk about the wiring itself We know that: Information is transferred over wires Much of the wiring is provided by the motherboard
Buses Indeed, the wiring on the motherboard transfers information Important channels (‘highways’) of information are called BUSES Like a highway, multiple devices all share the same bus There may be 10 devices on the bus, but any two of them can use the bus to communicate
Buses: Multiple devices sharing the same lines
Buses However, we know that to transmit USEFUL information, we need more than 1 bit!
Buses: Multiple Bits It is possible to send multiple bits over a single wire Send them one at a time! In SERIAL
Buses: Multiple Bits However, it is faster if we can send multiple bits at the same time In PARALLEL
Buses: Multiple Bits So parallel is faster But, how do we send multiple bits at the same time? MULTIPLE WIRES!
Buses: Multiple Bits So: Information needs to be passed as quickly as possible on the motherboard’s buses Parallel is faster than serial Multiple wires are needed for parallel Therefore, BUSES ARE MADE UP OF MULTIPLE WIRES
Buses: Multiple, Parallel Wires If you look at the motherboard, you can see the buses They are the groups of lines that run in parallel
Buses Data is passed around on the motherboard using buses Components plug into the motherboard to connect to other devices Therefore, components connect to the buses! As we learn about other connectors, you will be able to see that they all connect to a bus!
Slots/Ports/Etc.: Familiarity Required There is a great deal of information on various expansion cards, ports, etc. You are not expected to memorize it all! Read over for familiarity What you will be expected to know: Only for types mentioned in the presentation Name (acronym, not the full name) The degree to which it is used today What types of devices typically use the interface How fast it is (relative to other ports which can be used for the same type of device)
Expansion Slots and Ports We know that we can connect lots of different devices to our computer These items must connect to the motherboard somehow There are two primary methods: Expansion Slots, and Ports
Expansion Slots Devices may be either INTERNAL (inside the ‘box’) or EXTERNAL Sometimes, we have a choice E.g., Modems Expansion slots are often used for INTERNAL devices
Expansion Slots In earlier readings (p. 14), you learned about circuit boards Virtually all electronic devices use circuit boards With an external device, you need to package up that circuit board, build a way for it to connect to the computer, etc. Expensive!
Expansion Slots With internal devices, we can avoid all of this expense! Just provide a circuit board, with no additional packaging This is called an EXPANSION BOARD Plugs directly into the motherboard
Things to notice… They are normal circuit boards Lots of components! They each have a set of ‘pins’ which plugs into the slot These pins are the wires that connect it to the motherboard Why so many pins? They connect to a BUS on the motherboard Lots of lines for information Other wires for controlling the board, etc.
Expansion Slots/Buses If you look on the motherboard, you will see that there are ‘bus’ wires running to each of the expansion slots Plugging a board in connects it to a bus The board can now communicate with the motherboard, and other components!
Expansion Boards/Slots An expansion board plugs into an expansion slot This is an example of an INTERFACE! What do we know about interfaces? They have to match EXACTLY For this reason, they are often standardized
Expansion Slot Standards Expansion slots are standardized To ensure that any manufacturer’s board will work with anyone else’s motherboard There are a handful of standard interfaces that you need to know about
ISA Slots… Are an older technology (Supports 16 data bits) May not exist on newer PCs Slower than current technologies Used for general internal peripherals Modems, sound cards, network boards, etc., etc.
PCI Bus/Slots New technology (32 data bits) Primary general-purpose slot for modern PCs Use for modems, sound cards, network boards, (sometimes) video, etc. Much faster than ISA That’s why it replaced ISA!
AGP stands for Accelerated Graphics Port Only used for VIDEO cards Most common graphics interface today Normally, you only have 1 AGP slot on your motherboard Very, very fast Much faster than PCI Needs to be fast, to support games!
Slots on a Motherboard
Slots on another Motherboard
How do you tell the difference? You get to know them… Color can provide you a clue PCI are normally white ISA are black There is only one AGP… You normally know what type of card you have It will only fit one type of slot You can then tell what type of slot it is!
How can you tell what a board does? Usually, you can tell by the jacks (ports) on the back of the board Headphone-type jacks-> sound card Telephone jack-> modem Network jack->network card Monitor(VGA) port->video card
Ports We’ve discussed the role of expansion slots Internal devices However, sometimes devices are external Why, if it’s more expensive? Convenience – portability, etc. Physical requirement – can you imaging using an internal printer, or joystick?
Ports How do external devices connect They use cables The cables plug into the computer They plug into PORTS! So, a port is similar in idea to a slot, but it’s for external use
Ports If you want to see ports, look at the back of your computer All of those sockets are ports How do we make sense of them? Again, there are standards for ports You’ll find plugs will only plug into ONE TYPE of socket Prevents you from inserting the plug in the wrong socket
Serial Ports Also known as RS-232 Very simple, found on virtually every PC Very OLD! ‘Serial’, because the only have one wire to send data Data is sent one bit after another Slow! Other wires for control, etc. General purpose port Not used much now, because of speed Now, sometimes used for mice, PDAs, Digital Cameras, etc.
Parallel Ports Also very old Faster than serial ports Instead of one wire for data, it has 8 wires, and sends 8 bits at a time (‘in parallel’) Hence, more pins than serial! Other wires for control, etc. Often called ‘Printer Ports’ Used mostly for printers, even today, and sometimes scanners
USB Ports A much newer type of port New devices support this type of port Much higher speed than serial, parallel General purpose port There are devices of all kinds which can use USB Network adapters, joysticks, keyboards, scanners, digital cameras, hard drives, etc., etc.! USB stands for Universal Serial Bus Because it is a BUS, you can connect multiple devices to it Using the same port Supports lots of advanced features See your text for details
PS/2 Ports Specialized ports, used only for keyboards and mice These devices don’t require much speed
A couple of other Ports There are two more types of connections which we will talk about They don’t strictly fit into either category Require a cable to be used But, often used for internal devices
IDE Connections IDE connections are used for hard drives, CD-ROMs and DVDs Found in virtually every PC Requires a cable A flat, ‘ribbon’ cable A cable can connect up to two devices Only used INTERNALLY
IDE Ports- Notice the name?
IDE Normally, a computer has two ports Each port can support two devices SO, a maximum of 4 IDE hard drives/CD- ROMs/DVDs in a system
SCSI SCSI is the last connection type we will talk about Small Computer System Interface Pronounced ‘scuzzy’ A very high speed connection Uses a BUS Can connect multiple devices to same port
SCSI Used for very high speed transfer Higher-end hard drives Higher-end scanners Etc. Drawback: Expensive Not normally found in a basic PC Needs to be added on
SCSI: Many different connectors
Assembling a PC A good, step-by-step guide to installation of parts can be found at: system-05.html
Summary You should have a broad understanding of how the various components of a computer connect with each other How they plug in How the data is transferred