Agriculture

1. Comp 501 – Computer
Applications for Agriculture
1. Introduction to Computers (Review)
2. Review of Microsoft Word and Excel
3. More Advanced Use of Microsoft Word and Excel
4. Using the Internet
5. Using PowerPoint Presentations

2. 1. Introduction to Computers (Review)
• Computers are automatic, electronic machines that:
 accept data & instructions from a user (INPUT)
 store the data & instructions (STORAGE)
 manipulate the data according to the instructions
(PROCESSING)
 store (STORAGE) and/or output the results to the user
(OUTPUT)

3. • Data – A collection of unorganized facts.
 May include numbers, words, image or sound.
 E.g. employee name, employee number, monthly salary
of an employee in a payroll.
• Information – organized data.
 more useful than data.
 Data information.
 E.g. the net pay of an employee in a payroll.
• Information & Communication Technology (ICT) – a
merger of two technologies: computing and high-
speed communication.
processing

4. • A computer has the following characteristics:
 It is automatic
 It is extremely fast
 It is highly accurate
 It is diligent
 It is highly versatile
 It has high power of remembering
 It has no IQ
 It has no feeling
Characteristics of Computers

5. Types of Computers

6. Classification (Cont’d)
• Analog computers process analog data.
- By analog, we mean continuously varying quantity.
• Digital computers process digital data.
- Digital data assume one of two values, 1 (high) or 0 (low).
- Hybrid computers exhibit features of analog and
digital computers.

7. Types of Computers (Cont’d)
Supercomputers
• High capacity
• Used by large organizations
• Tracking space
• Tracking weather
Mainframe computers
• Occupies specially wired, air-
conditioned rooms
• Capable of great processing
speeds and data storage
• Not as powerful as
supercomputers

8. Types of Computers (Cont’d)
Minicomputers
• Known as midrange computers
• Medium-size companies
• Used by departments of large
companies
Microcomputers
• Least powerful
• Widely used
• Four types
• Desktop
• Notebook or laptop
• Tablet PC
• Handheld

9. Types of Computers (Cont’d)
• Based on their applications, computers are classified
as:
 General–purpose computers – used for a variety of tasks
- E.g. the PCs in wide use in our labs and Internet cafés, or
Special–purpose computers – perform specific tasks.
- E.g a computer that guides a missile

10. Components of a Personal Computer (Desktop)
• Hardware – physical components that you can feel and touch.
System Unit
Mouse
Keyboard
Monitor
CD-ROM
Drive
Floppy Disk
Drive

11. Inside the System Unit
Motherboard
CPU
(Central Processing Unit)

12. Inside the System Unit (Cont’d)
SIMM
(Single Inline Memory Module)
HDD
(Hard Disk Drive)
Power Supply

13. Personal Computer – Schematic Diagram
Ports
CPU
RAM
Disk
controller
Graphics
card
Sound
card
Network
card
Printer
Mouse
Keyboard
Modem
Monitor
Speakers
bus
Computer

14. Hardware Devices
•Input Devices (Get information)
• Keyboard
• Mouse
• Scanner
•Output Devices (Give information)
• Screen/monitor
• Printer

15. Hardware Devices (Cont’d)
•Processing Device (Arithmetic/logic/repetition)
–Central Processing Unit (CPU)
 286, 386, 486, Pentium
 Has three basic parts
• Arithmetic Logic Unit (ALU)
• executes all the arithmetic and logic instructions
• Control Unit
• decodes instructions and determines which is next to be executed
• Buses/Registers
• Buses are paths for information entering/exiting the CPU
• Registers are memory for processing information

16. Hardware Devices (Cont’d)
• The CPU continuously follows the fetch-decode-execute cycle:
fetch
Retrieve an instruction from main memory
decode
Determine what the
instruction is
execute
Carry out the
instruction

17. Hardware Devices (Cont’d)
• Storage – stores programs, data and information.
• Two types: Primary and secondary
• Primary Storage (main memory)
• On board memory (located on the motherboard)
• Very fast, but expensive
• Two types
• RAM – Random Access Memory
• ROM – Read Only Memory

18. Hardware Devices (Cont’d)
• RAM - Random Access Memory
• Read/write capability
• Contents lost when computer is turned off (volatile)
• A program must be in RAM for it to execute
• 4GB to 16GB for a typical desktop computer

19. Hardware Devices (Cont’d)
• ROM - Read Only Memory
• Read but not write capability
• Permanent (non volatile)
• Stores the preliminary instructions to be executed when
the computer is turned on, for example
• To check RAM
• To check communications with peripheral devices
• Bootstrap loader program

20. Hardware Devices (Cont’d)
Address
9278
9279
9280
9281
9282
9283
9284
9285
9286
Large values are
stored in consecutive
memory locations
10011010
Each memory cell stores a set
number of bits (usually 8 bits, or
one byte)
Content
Main memory is
divided into many
memory locations
(or cells)
Each memory cell has a
numeric address, which
uniquely identifies it

21. Hardware Devices (Cont’d)
• Secondary Storage (secondary memory)
• External devices (not on the motherboard); either inside or
outside the computer
• Store programs and data permanently
• Slower, but cheaper
• RAM - nanoseconds, Drive - milliseconds
• Different sizes/styles
• Floppy Disk - 1.44 MB (portable)
• Zip Drive - 100-750MB (portable)
• CD - 650MB (portable)
• Jaz Drive – 1-2GB (portable) discontinued
• Hard Disk Drive >=20GB (portable and non-portable)
• Tape - 50GB (portable, very slow)
• Flash drives - >= 128MB (portable)

22. Hardware Devices (Cont’d)
• Other devices
• Port - for connecting peripheral devices
• PS2, USB, Parallel and Serial ports
• Modem (internal or external)
• For communicating over telephone lines
• NIC (Network Interface Cards)
• For connecting to a network
• Other Expansion Cards
• Fit into expansion slots; lend computer additional capability (e.g.
sound card)

23. Computer Software
• Program – set of instructions that tell the computer
what to do.
• Software – a collection of programs
• Computer gets its life from the blending of hardware
and software.
• Two categories of software:
• System software - essential for the computer to function; it helps
the computer manage its own tasks and devices.
• Application software - enables user perform specific tasks.

24. • System software consists of:
• Operating system – to manage processes, memory allocation, file,
device, and security as well as provide user interface.
• Device drivers – to allow the computer recognize and communicate
with external devices like printer, camera, scanner, etc.
• System utilities –maintenance of systems and performing routine
tasks like defragmenting, compressing, backing up, and scanning for
viruses.
Computer Software

25. • System development programs – allow to write and construct programs.
They include:
• Programming language – to write programs.
• Translator – to convert programs to machine language: Assembler, Interpreter and
Compiler
• Linker – links modules and libraries into one coherent program.
• Loader – loads and relocates executable program in the main memory.
• Application Software – used to perform specific tasks. It includes:
• Word processing like MS Word
• Spreadsheet like MS Excel
• Database Management Systems like MS Access
• Graphics software like Corel Draw and Paint.
Computer Software

26. Relationship Between Hardware and Software
System Software
Hardware
Application Software
Application layer executes on the system software layer, which lies on the hardware layer.

27. Data Communications and Computer
Networks

28. Data Communications and Computer
Networks
• Data communication - the exchange of data between two devices.
• It deals with:
• the transfer of data,
• the method of transfer, and
• the preservation of the data during the transfer.

29. Data communication & Computer Networks (cont’d)
• Five basic components:
• Message – data to be sent.
• Sender – sending device like a computer
• Receiver – receiving device like a computer
• Media – physical path followed by data.
• Protocol – rules governing the communication.
• Data transmission modes
• Simplex – unidirectional.
• Half duplex – bidirectional, at different times.
• Full duplex – bidirectional and at the same time.

30. • Bandwidth – rate at which data is transmitted
• Expressed in bits per second (bps). Other units include
• Kilobits per second (1 Kbps = 103 bps)
• Megabits per second (1 Mbps = 106 bps)
• Gigabits per second (1 Gbps = 109 bps)
• Terabits per second (1 Tbps = 1012 bps)
• Narrow band – slow rates (<256 Kbps)
• Broadband – high rates (>=256 Kbps)
Data communication & Computer Networks (cont’d)

31. Transmission Media
• Two broad categories: guided and unguided.
• In guided media, cable is used to guide the data flow.
• In unguided media, no cable exists to guide the data flow
• Guided media may be copper or optical fiber cables.

32. • For data communication, we use the following copper cables:
Transmission Media (cont’d)
– Coaxial cable – consists of a single copper conductor at
its center, an outer braided metal shield and a plastic
layer insulation in-between.
• Two types of coaxial cable are:
– ThinNet (or 10Base2) – where the 2 refers to the max segment length,
which is 185m (200m)
– ThinNet cables use BNC connectors
– ThickNet (or 10Bas5) – where the 5 refers to the max segment length,
which is 500m
– In both cases, the 10 refers to the max. transmission rate, which is
10Mbps
Coaxial cable
BNC Connector

33. • Twisted Pair Cable – made of two or more pairs of
insulated copper wires twisted together.
• May be unshielded or shielded (UTP/STP).
• UTP is the most popular and is generally the best
option for most networking.
• It is cheap, easy to wok with and supports high transmission
rate.
• Currently, Cat5 (100MBps), Cat6 (1Gbps) and Cat 7 (10Gbps)
are in use
• It uses RJ-45 connectors
Transmission Media (cont’d)

34. • STP has shield to protect data from EMI and RFI.
• It is suitable for environments with electrical interference.
• The extra shielding can make the cables quite bulky.
Transmission Media (cont’d)

35. • Optical fiber cables are also used in data communications.
• Much longer distance than copper cables.
• Support higher transmission rate.
• Immune to interference.
Transmission Media (cont’d)
Connectors

36. Specification Cable Type Maximum length
10BaseT Unshielded Twisted Pair 100 meters
100BaseT Unshielded Twisted Pair
100 meters
10Base2 Thin Coaxial 185 meters
10Base5 Thick Coaxial 500 meters
10BaseF Fiber Optic 2000 meters
Transmission Media (cont’d)
Summary for guided media

37. • Unguided media are used where guided media cannot be used.
• They may use:
• Infra-red
• For short distances, with no obstacle
• Radio wave
• For medium distances, say 100m
• Micro wave
• For longer distances
• Terrestrial or satellite communication
Transmission Media (cont’d)

38. Networking Devices
• Networking devices inter-connect end devices.
• They include:
– Network Interface Card (NIC)
• Inserted into the computer expansion slot.
• provides physical, electrical, and electronic connections to the
network media.
– Repeater
• extend the maximum reach of a network.
• receive signals on one port, amplify them, and repeat them out
on the other port
– Hub
• Multiport repeater
• Central device in a star topology network

39. • Bridge
• separates a single network into two segments.
• improve network performance
• Switch
• high-performance, multi-interface bridges.
• filter transmission of data into unintended segments.
• Router
• connects multiple networks into an internetwork.
• can decide how best to get network data to its destination.
Networking Devices

40. Computer Network
• A computer network is a connection of two or more computers to share
information and resources.
• Based on the area they cover, networks may be classified as:
• Local Area Network (LAN) – a single room, building or campus.
• Metropolitan Area Network (MAN) – spans a city.
• Wide Area Network (WAN) – spans more than one city.

41. Computer Networks (cont’d)
• WANs differ from LANs in the following ways:
• WANs cover greater distance.
• WAN speeds are slower.
• WAN connections can be on demand or permanent; LAN
connections are permanent.
• Media used by WANs are typically public while those used by LANs
are private.

42. • Based on security and access, networks are classified into peer-to-peer
and client/server networks .
• Peer-to-peer networks
• All computers are equal
• No dedicated client or server
• Security is not centralized
• Network is not scalable; good only for <= 10 computers
• No specialized network operating system is required.
Computer Networks (cont’d)

43. • Client/Server Networks
• Dedicated servers to provide services/resources
• Security is centralized
• Network is scalable; can have hundred of computers
• Specialized network operating system is required.
Computer Networks (cont’d)

44. • Advantages of networks include:
• Speed – info. Can be transported at high speed.
• Cost – software can be shared.
• Security – centrally-stored software are more secure.
• Centralized software management is possible.
• Resources can be shared.
• Communication is enhanced.
• Workgroup computing is possible.
Computer Networks (cont’d)

45. • Disadvantages of networks include:
• Installation cost could be high.
• Requires administrative expertise and time.
• In the event that central devices like server fail, the entire system fails.
• Cables may break.
Computer Networks (cont’d)

46. • Network Topology - the physical configuration of computers, cables and
network devices.
• Common configurations include the bus, star ring and mesh topologies.
• Bus topology
• all computers are connected to a single cable.
• cable is terminated at its ends to avoid signal bouncing.
• Data on the cable is seen by all computers, but only that to which it is addressed will pick it
and respond to.
Computer Networks (cont’d)

47. • Advantages of a Bus Topology
• Easy to connect a computer or peripheral.
• Requires less cable.
• Disadvantages of a Bus Topology
• Entire network shuts down if there is a break in the main cable.
• Difficult to identify the problem if the entire network shuts down.
• Network can slow down in heavy traffic.
Computer Networks (cont’d)

48. • Star Topology
• Each computer is connected to a central device (hub) by a separate cable.
• All data are transmitted through the
Central device.
Computer Networks (cont’d)
–Advantages
• Easy to install and wire.
• No disruptions to the network when connecting or removing devices.
• Easy to detect faults and to remove parts.
• Failure of one computer does not affect the rest of the network
–Disadvantages
• Requires more cable length than a linear topology.
• If the hub or concentrator fails, nodes attached are disabled.
• More expensive than linear bus topologies because of the cost of the concentrators.

49. • Ring Topology
• Computers are connected to form a ring.
• Data moves down a one-way path from one computer and if the next computer is the
recipient it accepts the data; otherwise it amplifies it and sends it to the next computer
down the path.
• Any break disrupts the entire network.
• Advantages of a Ring Topology
• System provides equal access for all computers.
• Performance is even despite many users.
• Disadvantages of a Ring Topology
• Failure of one computer can impact the rest of the network.
• Problems are hard to isolate.
• Network reconfiguration disrupts operation.
Computer Networks (cont’d)

50. • Mesh Topology
• Each computer is directly connected to every other computer.
• It uses several cabling. For n computers,
½ n(n-1) cables are required.
• Mesh topology is rarely used, and then only in a WAN environment.
• Advantages of a Mesh Topology
• System provides increased redundancy and reliability as well as ease of troubleshooting.
• Disadvantages of a Mesh Topology
• System is expensive to install because it uses a lot of cabling.
Computer Networks (cont’d)

51. • Considerations When Choosing a Topology:
• Money
• A linear bus topology is the least expensive to install a network.
• Length of cable needed
• The linear bus network uses shorter lengths of cable.
• Future growth
• With a star topology, expanding a network is easily done by adding another concentrator.
• Cable type
• The most common cable is the UTP, which is most often used with star topologies.
Computer Networks (cont’d)

52. • Media Access – shared media requires that some rules be in place for
devices to effectively use the media.
• Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
• Used in Ethernet networks.
• Computers can send data only when the media is idle, can detect collision and back off in that
event.
• Token Passing
• Used in ring topology.
• A special frame called frame circulates in the ring; when it passes through a computer that wants
to send data, it will be held by that computer until it is over with sending its data. When the
computer finishes sending its data, it releases the token which then again circulates.
Computer Networks (cont’d)