Without reference, identify principles relating
to Computers with at least 70 percent
accuracy.
 People – Despite all the technological advances that have
occurred over the years, computer users are still the most
important component in a computer system. They input,
review, verify, and manipulate data. Along with the users
are the designers and engineers who engineers who create
the software and hardware for computer use
 Application Software - Any instructions or collection of
related programs designed to be carried out by a computer
to satisfy a user’s specific needs are applications software.
You will frequently encounter this type of software when
dealing with computer controlled medical devices.
 Procedures – A procedure is a specific sequence of steps
performed to complete one or more information processing
activities. A person usually responds to these steps
initiated by the computer in response to the date fed into it.
The procedures that need to be followed for each computer
system will depend on the system and application software
being used.
 Data/information – The purpose of a computer system is to
convert data into usable information. Data is raw,
unevaluated facts, figures, concepts, or instructions. This
raw material is processed into useful information.
Information is the product of data processing. This
processing includes refining, summarizing, categorizing,
and otherwise manipulating data into a useful form for
decision-making.
 Connectivity – This occurs when one computer system is set
up to communicate with another computer system. As in a
network. The manner in which the various individual
systems are connected (for example: by phone lines,
coaxial cables, fiber optics, infrared, satellite, or category 5
cable) is an element of the total computer system.
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Computer categories – There are four basic
categories
 Supercomputers – The supercomputer can use over 120
microprocessors operating in parallel, and 128 gigabytes of
memory to handle up to eight trillion floating point
operations per second or FLOPS. These computers are
markedly faster than ordinary mainframe computers.
Supercomputers are used in the areas of government,
industry, scientific and biomedical research.
 Mainframe computers – This is a large computer housed in
a controlled environment, which can support the processing
requirements of 100 to 500 users at a time. They are used
in banks, large insurance companies, or a large university.
Each user has a terminal that is linked to the mainframe
computer.
 Minicomputer – The minicomputer is similar to, but less
powerful than a mainframe computer. It can support from
10 to 100 users. Many small and medium size companies
use this type of system; however, with the increased power
of the microcomputer, many companies are replacing their
minicomputers with networked microcomputers. This is
the computer system that you’ll likely be dealing with the
most.
Just Kidding!
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Central processing unit
 The Function of the Expansion Bus
• Expansion slots on the motherboard allow flexibility when
adding hardware devices to your PC
• When IBM invented the PC, they realized that they needed a
way to add new devices to the PC as they became available
• IBM came up with expansion slots as a way of adding these
new devices
• These slots are standardized connections that provide a
common access point for installation of devices
• All expansion slots on the motherboard connect to the
external data bus (EDB) and address bus
• This gives the CPU access to the hardware items to get work
done more efficiently
 The Expansion Bus
• It as, as its name implies, an expansion of the EDB
• The expansion bus is part of the EDB
• Sometimes called the system bus or the EDB; hard wired
between the CPU, main memory and a chip called the North
Bridge
• This can be misleading
• The EDB connects to everything in the computer, i.e. the
system bus part or the expansion bus part
 The Chipset
• When first introduced the PC could have over 100 chips on a
motherboard
 Each of these chips had its individual purpose
 An example of one of these chips was the 8259
 This chip was the interrupt controller chip
• Motherboards were very expensive during that time
period and one of the main reasons was that buying all
those chips and putting them on the motherboard was
expensive
• In 1986, Chips and Technology Inc. (now owned by
Intel), came out with a revolutionary new chip called
the 82C206
 The 82C206 had almost all the functions required by the
motherboard built into it
 The 82C206 only needed four support chips
Dropping the chip count down to five chips greatly reduced
the manufacturing cost of motherboards
• A number of companies started producing these
multi-purpose chips, now called chipset
• In 1993 Intel decided to go full force in the
chipset business and by 1994 dominated
the market
Only a few chipset makers have survived.
They are Intel, Ali, VIA and SiS
The reason for Intel moving so strongly into the
chipset business is they got tired of waiting for
chipset manufacturers to come out with a chipset
for whatever new processor Intel introduced
Before 1994, after the introduction of a new
processor, customers had to wait for more than a
year until they could buy a motherboard for that
new processor
Now, new motherboards and processors are
available for purchase on the day of introduction
 This lesson will only cover one
chipset of the many available
 It is the 440BX
The 440BX is a Pentium II class chipset
It has three main chips in the set
 The first chip is the "North bridge"
 The Second chip is the "south bridge"
 The third chip is an I/O chip
North Bridge
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The 440BX
• The North Bridge or host bridge is an 82443BX chip
• The South Bridge is an 82371AB PCI-TO-ISA/IDE XCELERATOR,
also called a PIIX4
• The third chip is an I/O control chip
• The 82443BX has the following features an characteristics:
 Optimized for the Pentium II at 100 MHz EDB
 Will work at 66MHz for the Celeron
 The Pentium III can also work with this bridge
 A DRAM controller (MCC) that can support up to 1 GB using DIMMs
» It is the Chipset that limits the amount of RAM and the type of Ram installed on a
motherboard
» Supports up to 4 double-sided DIMMs and ECC
» DIMMs must be SDRAM
‫ ـ‬If the EBD is operating at 100 MHz the SDRAM must be PC-100
‫ ـ‬PC-100 is a specification for timing inside the DRAM modules
 Supports a PCI bus
•
Peripheral Component Interface or Interconnect
(PCI)
 PCI is the latest type of Expansion Bus (AGP at this time
is a port not a bus)
 PCI is completely independent of the CPU
 This flexibility allows its use with any other expansion
bus as well
 Sometimes called the mezzanine bus since it physically
sits between the North and South Bridge
 All data transferred by the South Bridge must go through
the PCI bus to the North Bridge to get to main memory,
the CPU or the AGP port
• The PCI Bus acts as an intermediary between PCI devices,
devices that go through the South Bridge and the EDB
• The PCI Bus acts as a bus master by taking control of the
EDB to transfer data when the CPU is not using the EDB

Advanced Graphics Port (AGP)
 AGP is a port, not a bus, because currently its only
use is for video
 AGP enables high-speed-direct access to the
system memory by the graphics controller rather
than forcing it to pre-load the data into the video
cards memory
 AGP does not have to act as an intermediary for
devices the way the PCI bus does
 AGP is a 32-bit port

Input/Output (I/O) Addressing
 Cover how the CPU can communicate with one particular device of an modern interfaced system
 The CPU communicates with devices by each having a unique I/O Address
 The CPU places a low on the M/ - wire to notify devices that it is NOT accessing a memory location,
instead, it "calls" a hardware device to perform a function
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The CPU places a low on the to transfer data to memory or I/O device
• The CPU places a low on the to receive data from memory or an I/O device
The Address Bus is at least 20 wires.
When the M/ is low, only the first 16 Address wires are monitored.
The wire that tells the system Memory or I/O is the M/ wire
All devices, both soldered to the motherboard or plugged into a port or slot must have a unique
address assigned
This unique address allows the CPU to talk / listen to only one device at a time, and only the one
represented by the unique address
The I/O Address for devices is usually a specific RANGE of addressable locations
ALL devices must have and I/O Address assigned and no two devices can have overlapping ranges
•
Some of the ranges are already reserved through the BYOB or System BIOS; for example the
Primary hard drive controller's addresses are 01F0-01FF
•
We normally only refer to the first location of the range, which is called the base I/O address.
Example: 1F0
•
Many devices, such as sound cards, modems, etc. have jumper settings and/or device drivers
that allow adjustment of the I/O Address both on the device or through software
 When installing a new hardware device that requires you to assign the I/O
Address manually, you should ALWAYS read the manual
 A conflict occurs when two devices share an I/O Address range, and
neither will respond to commands
 The best way to avoid this, though it won't prevent it, is to document all assigned
I/O addresses for each device
 Get a software program that will display the I/O addresses. (Windows has one)
 If maintaining a large group of machines that have identical hardware devices, you
should configure them identically for simplicity

Interrupt Requests (IRQs)
 The means by which a hardware device initiates communication with the
CPU is through a mechanism called an Interrupt
 Every CPU has an input wire called interrupt signal (INTR)
 If this wire goes high, the CPU will finish what it is doing and then answer,
Interrupt Acknowledge (INTA), the INTR
 The original PC had a chip called the 8259 that had 8 inputs, (0 through 7)
called IRQs and one output called INTR

COM and LPT Ports
 It is very important that the I/O Address and IRQ is
unique for each hardware device
 In some cases, such as COM and LPT ports, there are
already preset combinations assigned
 Ports (short for portal, or two-way access) were created
to simplify installation, programming and operation of
hardware devices like modems and printers
• An external modem itself does not have any settings for I/O
Address or IRQ
• Instead you select a COM Port which already has a preset I/O
Address and IRQ
• In this way, a programmer does not need to know the I/O
Address or IRQ for a specific modem, only the COM port

Installing a New Device
 Read the manufacturer's literature
 Remember to always write down the I/O Addresses, IRQs and DRQs of all
devices in the PC
 Confirm settings, especially if jumpers are being utilized
 In the event a software program cannot isolate the conflict, you can install a
POST Card

Plug n Play (PnP)
 A set of standards that govern how a device will be self-configuring
 You need a PnP device, PnP Operating System and PnP BIOS to make it work
 In theory all you do is install the device, the BIOS and OS will configure the
device in your system by setting the I/O address, IRQ and device drivers
 PnP works most of the time
 The problem with PnP is the ISA Bus
 ISA is not PnP and sometimes interferes with installation of a PnP device
 ISA devices are known as Legacy devices
 Some manufacturers are finally making Legacy free PC's
 Legacy free PC's have a better PnP because there is no ISA bus

USB - Universal Serial Bus
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USB is another set of standards that governs a new serial port
USB 2.0 (the second revision) has a fast transfer rate of 60MB/sec
You can install up to 127 devices at a time on one USB port
You do not have to set anything: just plug the device in and use it
You can also plug in a new device while the system is turned on
The OS will pick up the new device and you can use it
No need to turn the system off to install a device
You need a USB plug on the back of your PC and a USB ready OS
Win95 and newer are USB ready
This bus is still young. If all the hype is true, then we truly have a
PnP Bus, the USB