Week 10
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Transcript of Week 10
Week 10
CPU/Motherboard/Memory/Buses/Slots/Ports
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 ProcessorThe 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)Input Output
Storage
CPUs: Different packages
CPUs: Things to noticeSee 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 computerPlugs into the
‘Motherboard’ The pins all plug
into a socketWhat is a
motherboard?
MotherboardsWe’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
Motherboard
MemoryWe 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, speedsRAM 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 likeLong, thin chips Inserted in motherboard in rows
How RAM connect to motherboard
Notice the markings on the board?
BusesWe 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 BUSESLike 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
BusesHowever, 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 BitsHowever, it is faster if we can send
multiple bits at the same time In PARALLEL
Buses: Multiple BitsSo parallel is fasterBut, how do we send multiple bits at the
same time? MULTIPLE WIRES!
Buses: Multiple BitsSo:
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 PortsWe 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 SlotsDevices 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 SlotsWith 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
An Example
An Example
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/SlotsAn 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 StandardsExpansion 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
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 Slots
PCI Slots
PCI Bus/SlotsNew 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 Slot
AGP Slot 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
PortsWe’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?
PortsHow 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 PortsAlso very oldFaster 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 PortsSpecialized ports, used only for
keyboards and miceThese devices don’t require much
speed
A couple of other PortsThere 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 Cable
IDENormally, a computer has two portsEach port can support two devices
SO, a maximum of 4 IDE hard drives/CD-ROMs/DVDs in a system
SCSISCSI is the last connection type we will
talk about Small Computer System Interface Pronounced ‘scuzzy’
A very high speed connectionUses a BUS
Can connect multiple devices to same port
SCSIUsed 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 PCA good, step-by-step guide to
installation of parts can be found at:
http://www6.tomshardware.com/howto/01q1/010115/pcsystem-05.html
SummaryYou 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