Netiquette
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Sunday, September 5, 2010
Monday, August 9, 2010
Virus
Virus:
A computer virus is a computer program that can copy itself and infect a computer. The term "virus" is also commonly but erroneously used to refer to other types of malware.
Viruses can increase their chances of spreading to other computers by infecting files on a network file system or a file system that is accessed by another computer.
Malware:
Short for malicious software, is software designed to infiltrate a computer system without the owner's informed consent.
Malware includes computer viruses, worms, trojan horses, spyware, crimeware, most rootkits.
Worm:
is a self-replicating malware computer program. It uses a computer network to send copies of itself to other nodes (computers on the network) and it may do so without any user intervention. This is due to security shortcomings on the target computer. Unlike a virus, it does not need to attach itself to an existing program. Worms almost always cause at least some harm to the network, if only by consuming bandwidth, whereas viruses almost always corrupt or modify files on a targeted computer.
Trojan Horse:
A Trojan horse, or Trojan, is malware that appears to perform a desirable function for the user prior to run or install but instead facilitates unauthorized access of the user's computer system. "It is a harmful piece of software that looks legitimate. Users are typically tricked into loading and executing it on their systems", as Cisco describes.
A Trojan horse may modify the user's computer to display advertisements in undesirable places, such as the desktop or in uncontrollable pop-ups, or it may be less notorious, such as installing a toolbar on to the user's Web browser without prior mentioning.
Once a Trojan horse has been installed on a target computer system, a hacker may have access to the computer remotely and perform various operations, limited by user privileges on the target computer system and the design of the Trojan horse
Spyware:
Spyware is a type of malware that is installed on computers and collects little bits of information at a time about users without their knowledge. The presence of spyware is typically hidden from the user, and can be difficult to detect. Typically, spyware is secretly installed on the user's personal computer. Sometimes, however, spywares such as keyloggers are installed by the owner of a shared, corporate, or public computer on purpose in order to secretly monitor other users.
Crimeware:
Crimeware is designed to perpetrate identity theft in order to access a computer user's online accounts at financial services companies and online retailers for the purpose of taking funds from those accounts or completing unauthorized transactions that enrich the thief controlling the crimeware.
Rootkit:
Rootkits can target the BIOS, hypervisor, boot loader, kernel or less commonly, libraries or applications.
The most common forms of rootkit either damage the systems they occupy or redirect the systems' resources for purposes ranging from pranks to gratifying their authors' egos to crime.
Virus vs. Worm:
A virus stays on your computer and your computer only.
Worms crawl through networks.
Unlike a worm, a virus cannot infect other computers without assistance. It is spread via trading programs with others (file sharing programs, email).
Spyware vs. Adware:
Symptoms: Sluggish Pc, Increased pop-ups, homepage changes, strange search results.
Both are data miners, meaning they are looking for information. Both cause the above symptoms.
Can lead to identity theft.
9 out of 10 pc’s are infected.
Good place to look for info? http://www.webroot.com/spywareinformation
Spyware Removal:
You can try to do it manually- but is often very difficult.
Often it can disrupt major computer processes.
You can check out the following free programs:
AdAware
SpySweeper (both versions, free&pay)
NOTE: Please be careful when downloading these tools, some programs claim to remove spyware, but instead, come with their own spyware embedded.
Top Spyware Threats:
PurityScan
N-Case
Gator
CoolWebSearch
Tansponder
ISTbar/AUpdate
KeenValue
Internet Optimizer (bargain buddy)
Perfect Keylogger
TIBS Dialer
For more information on these, visit:
http://www.webroot.com/spywareinformation/spywaretopthreats/
A computer virus is a computer program that can copy itself and infect a computer. The term "virus" is also commonly but erroneously used to refer to other types of malware.
Viruses can increase their chances of spreading to other computers by infecting files on a network file system or a file system that is accessed by another computer.
Malware:
Short for malicious software, is software designed to infiltrate a computer system without the owner's informed consent.
Malware includes computer viruses, worms, trojan horses, spyware, crimeware, most rootkits.
Worm:
is a self-replicating malware computer program. It uses a computer network to send copies of itself to other nodes (computers on the network) and it may do so without any user intervention. This is due to security shortcomings on the target computer. Unlike a virus, it does not need to attach itself to an existing program. Worms almost always cause at least some harm to the network, if only by consuming bandwidth, whereas viruses almost always corrupt or modify files on a targeted computer.
Trojan Horse:
A Trojan horse, or Trojan, is malware that appears to perform a desirable function for the user prior to run or install but instead facilitates unauthorized access of the user's computer system. "It is a harmful piece of software that looks legitimate. Users are typically tricked into loading and executing it on their systems", as Cisco describes.
A Trojan horse may modify the user's computer to display advertisements in undesirable places, such as the desktop or in uncontrollable pop-ups, or it may be less notorious, such as installing a toolbar on to the user's Web browser without prior mentioning.
Once a Trojan horse has been installed on a target computer system, a hacker may have access to the computer remotely and perform various operations, limited by user privileges on the target computer system and the design of the Trojan horse
Spyware:
Spyware is a type of malware that is installed on computers and collects little bits of information at a time about users without their knowledge. The presence of spyware is typically hidden from the user, and can be difficult to detect. Typically, spyware is secretly installed on the user's personal computer. Sometimes, however, spywares such as keyloggers are installed by the owner of a shared, corporate, or public computer on purpose in order to secretly monitor other users.
Crimeware:
Crimeware is designed to perpetrate identity theft in order to access a computer user's online accounts at financial services companies and online retailers for the purpose of taking funds from those accounts or completing unauthorized transactions that enrich the thief controlling the crimeware.
Rootkit:
Rootkits can target the BIOS, hypervisor, boot loader, kernel or less commonly, libraries or applications.
The most common forms of rootkit either damage the systems they occupy or redirect the systems' resources for purposes ranging from pranks to gratifying their authors' egos to crime.
Virus vs. Worm:
A virus stays on your computer and your computer only.
Worms crawl through networks.
Unlike a worm, a virus cannot infect other computers without assistance. It is spread via trading programs with others (file sharing programs, email).
Spyware vs. Adware:
Symptoms: Sluggish Pc, Increased pop-ups, homepage changes, strange search results.
Both are data miners, meaning they are looking for information. Both cause the above symptoms.
Can lead to identity theft.
9 out of 10 pc’s are infected.
Good place to look for info? http://www.webroot.com/spywareinformation
Spyware Removal:
You can try to do it manually- but is often very difficult.
Often it can disrupt major computer processes.
You can check out the following free programs:
AdAware
SpySweeper (both versions, free&pay)
NOTE: Please be careful when downloading these tools, some programs claim to remove spyware, but instead, come with their own spyware embedded.
Top Spyware Threats:
PurityScan
N-Case
Gator
CoolWebSearch
Tansponder
ISTbar/AUpdate
KeenValue
Internet Optimizer (bargain buddy)
Perfect Keylogger
TIBS Dialer
For more information on these, visit:
http://www.webroot.com/spywareinformation/spywaretopthreats/
Sunday, August 8, 2010
Basic Computer Maintenance
LCD Monitor:
- Do not touch or attach items to the screen.
- Turn off to clean.
- Spray mild window cleaner on a soft cloth.
- Do not spray directly on screen.
- Do not use paper towels.
Wires:
- Avoid pulling or putting stress on your wires.
- Avoid putting objects on top of wires.
- Always disconnect cords by grasping the plug, not the cord.
CPU:
-Turn power off before cleaning.
- Any type of household cleaner for outside.
- Once a month take off cover and gently blow off dust.
- Always disconnect power cord by grasping plug- not cord.
Surge Protectors:
- Use a surge protector to protect electronic devices from power surges.
- Will not offer 100% protection.
- To be safe, never use computer during a storm.
CD-ROM Drives:
- Always use the button to open and close the drive.
- Do not use compressed air to clean the floppy diskette, CD, DVD or Zip drives.
CDs and DVDs:
- Use a soft cotton cloth
- Wipe against the tracks starting from the middle and wiping outwards
- Never wipe with the tracks
- Water w/ soap or rubbing alcohol
Keyboard:
- Do not eat or drink while typing on your computer.
- Turn off before cleaning.
- Spray Windex onto cloth, not on keyboard
- Use Compressed air
Mouse:
- Clean the top of your mouse like your keyboard
- Scrape guck off bottom with your fingernail
Installing Software:
- Do not use “bootleg” software
- Be sure to reboot after each program is installed
- Test your computer for problems before installing another program
Protect Against Viruses:
- Don’t open email attachments from people you don’t know.
- If your computer suddenly starts acting strange, you should run a virus scan.
- Be careful about disks and CDs from other computers- not everyone has virus protection.
- Use a firewall. A firewall is a piece of software or hardware that helps screen out hackers, viruses, and worms that try to reach your computer over the internet.
- Be careful about what you download from the Internet!
- Be sure that everyone who uses your computer follows these rules!
General Troubleshooting:
- If your computer does not start the first thing to check is the power source… is it plugged in?
- If your computer locks up (freezes) the first thing you should do is restart the computer.
- If your document fails to print you should check the
a. paper supply,
b. power source,
c. paper feeder.
- If you install a new software program on your computer and it does not work the most likely reason is that you do not have enough memory.
- Do not touch or attach items to the screen.
- Turn off to clean.
- Spray mild window cleaner on a soft cloth.
- Do not spray directly on screen.
- Do not use paper towels.
Wires:
- Avoid pulling or putting stress on your wires.
- Avoid putting objects on top of wires.
- Always disconnect cords by grasping the plug, not the cord.
CPU:
-Turn power off before cleaning.
- Any type of household cleaner for outside.
- Once a month take off cover and gently blow off dust.
- Always disconnect power cord by grasping plug- not cord.
Surge Protectors:
- Use a surge protector to protect electronic devices from power surges.
- Will not offer 100% protection.
- To be safe, never use computer during a storm.
CD-ROM Drives:
- Always use the button to open and close the drive.
- Do not use compressed air to clean the floppy diskette, CD, DVD or Zip drives.
CDs and DVDs:
- Use a soft cotton cloth
- Wipe against the tracks starting from the middle and wiping outwards
- Never wipe with the tracks
- Water w/ soap or rubbing alcohol
Keyboard:
- Do not eat or drink while typing on your computer.
- Turn off before cleaning.
- Spray Windex onto cloth, not on keyboard
- Use Compressed air
Mouse:
- Clean the top of your mouse like your keyboard
- Scrape guck off bottom with your fingernail
Installing Software:
- Do not use “bootleg” software
- Be sure to reboot after each program is installed
- Test your computer for problems before installing another program
Protect Against Viruses:
- Don’t open email attachments from people you don’t know.
- If your computer suddenly starts acting strange, you should run a virus scan.
- Be careful about disks and CDs from other computers- not everyone has virus protection.
- Use a firewall. A firewall is a piece of software or hardware that helps screen out hackers, viruses, and worms that try to reach your computer over the internet.
- Be careful about what you download from the Internet!
- Be sure that everyone who uses your computer follows these rules!
General Troubleshooting:
- If your computer does not start the first thing to check is the power source… is it plugged in?
- If your computer locks up (freezes) the first thing you should do is restart the computer.
- If your document fails to print you should check the
a. paper supply,
b. power source,
c. paper feeder.
- If you install a new software program on your computer and it does not work the most likely reason is that you do not have enough memory.
Monday, July 26, 2010
Networking: Basic Topologies
Network Topologies
What is a Topology?
- The way in which the connections are made among all the computers is called the topology of the network.
- Network topology specifically refers to the physical layout of the network, specially the location of the computers and how the cable is run between them.
The most common topologies are:
Bus
Star
Ring
Mesh
Bus:
The bus topology is the simplest and most common.
It is often used when a network installation is small, simple, or temporary.
It is a Passive topology. This means that computers on the bus only listen for data being sent, they are not responsible for moving the data from one computer to the next.
- In an active topology network, the computers regenerate signals and are responsible for moving the data through the network.
- On a bus network, all the computer are connected to a single cable.
- When one computer sends a signal using the cable, all the computers on the network receive the information, but only one (Addressee) accepts it. The rest disregard the message.
Advantages of Bus:
1. The bus is simple, reliable in very small network, and easy to use.
2. The bus requires the least amount of cable to connect the computers together and is therefore less expensive than other cabling arrangements.
3. Failure of one node does not affect the rest of network.
Disadvantages of Bus:
1. Heavy network traffic can slow a bus considerably.
2. A break in the cable or lake of proper termination can bring the network down.
3. It is difficult to troubleshoot a bus.
Appropriateness of the bus topology:
- The network is small
- The network will not be frequently reconfigured
- The least expensive solution is required
- The network is not expected to grow much
Star Topology:
- In a star topology, each device has a dedicated point to point link only to central controller, usually called a hub/server/host.
- Each computer on a star network communicates with a central hub that resends the message appropriate computer(s)
- The hub can be active or passive.
- An active hub regenerate the electrical signal and sends it to all the computers connected to it.
Advantages of Star Topology:
1. It is easy to modify and add new computers to a star network
2. During adding/deleting a node network can function normally.
3. When the capacity of the central hub is exceeded, it can be replaced with one that has a larger number of ports to plug lines into.
4. Provide for centralised monitoring and management of the network.
5. Single computer failure do not necessarily bring down the whole star network.
Disadvantages of Star Topology:
1. If the central hub fails, the whole network fails to operate.
2. It cost more to cable a star network.
3. Require dedicated server and NOS
Appropriateness of Star Topology:
- It must be easy to add or remove client computer.
- It must be easy to troubleshoot.
- The network is large.
- The network is expected to grow in the future.
Ring Topology:
- In a ring topology, each computer is connected directly to the next computer in line, forming a circle of cable.
- It uses token to pass the information from one computer to another.
- Every computer is connected to the next compute in the ring, and each retransmit what it receives from the previous computer.
- The message flow around the ring in one direction.
- Ring is an active topology.
- There is no termination because there is no end to the ring
Token Passing method:
Token passing a method of sending data in a ring topology
A small packet, called the token passed around the ring to each computer in tern
If a computer has information to send, it modifies the token, adds address information and the data and sends it down the ring.
The information travels around the ring until it either reaches its destination or returns to the sender.
A token can circle a ring 200 meters in diameter at about 10,000 times a second.
Advantages of Ring Topology:
1. All the computers have equal access to the network.
2. Even with many users, network performance is even
3. Allows error checking, and acknowledgement.
Disadvantages of Ring Topology:
1. Failure of one computer can affect the whole network.
2. It is difficult to troubleshoot the ring network.
3. Adding or removing computers disturbs the network.
Appropriateness of Ring Topology:
- The network must operate reasonably under a heavy load
- A higher-speed network is required.
- The network will not be frequently reconfigured.
Mesh Topology:
- In a mesh topology, every devices has a dedicated point to point link to every other device.
- A fully connected mesh network therefore has n(n-1)/2 physical channels to link n devices.
- To accommodate that many links, every device on the network must have n-1 input/output ports.
Advantages of Mesh Topology:
1. Because of the dedicated link, no traffic between computers.
2. Failure of one node computer not affect rest of the network.
3. Because of the dedicated link privacy and security are guaranteed
4. Point to point links make fault identification and fault isolation easy.
Disadvantages of Mesh Topology:
1. Due to the amount of cabling and number of input output ports, it is expensive.
2. Large space is require to run the cables.
Variations of the Major Topologies:
1. Hybrid Star:
A star network can be extended by placing another star hub where a computer might otherwise go, allowing several more computers or hubs to be connected to that hub.
2. Star Bus:
The star bus topology combine the bus and the star, linking several star hubs together with bus trunks. If one computer fails, the hub can detect the fault and isolate the computer.
If a hub fails, computers connected to it will not be able to communicate, and the bus network will be broken into two segments that can not reach each other.
3. Hybrid Topologies:
Often a network combines several topologies as subnetworks linked together is a large topology.
For instance one department of business may have decided to use a bus topology while another department has a ring.
The two can be connected to each other a central controller in a star topology
When two or more topologies are connected together it forms a hybrid topology
What is a Topology?
- The way in which the connections are made among all the computers is called the topology of the network.
- Network topology specifically refers to the physical layout of the network, specially the location of the computers and how the cable is run between them.
The most common topologies are:
Bus
Star
Ring
Mesh
Bus:
The bus topology is the simplest and most common.
It is often used when a network installation is small, simple, or temporary.
It is a Passive topology. This means that computers on the bus only listen for data being sent, they are not responsible for moving the data from one computer to the next.
- In an active topology network, the computers regenerate signals and are responsible for moving the data through the network.
- On a bus network, all the computer are connected to a single cable.
- When one computer sends a signal using the cable, all the computers on the network receive the information, but only one (Addressee) accepts it. The rest disregard the message.
Advantages of Bus:
1. The bus is simple, reliable in very small network, and easy to use.
2. The bus requires the least amount of cable to connect the computers together and is therefore less expensive than other cabling arrangements.
3. Failure of one node does not affect the rest of network.
Disadvantages of Bus:
1. Heavy network traffic can slow a bus considerably.
2. A break in the cable or lake of proper termination can bring the network down.
3. It is difficult to troubleshoot a bus.
Appropriateness of the bus topology:
- The network is small
- The network will not be frequently reconfigured
- The least expensive solution is required
- The network is not expected to grow much
Star Topology:
- In a star topology, each device has a dedicated point to point link only to central controller, usually called a hub/server/host.
- Each computer on a star network communicates with a central hub that resends the message appropriate computer(s)
- The hub can be active or passive.
- An active hub regenerate the electrical signal and sends it to all the computers connected to it.
Advantages of Star Topology:
1. It is easy to modify and add new computers to a star network
2. During adding/deleting a node network can function normally.
3. When the capacity of the central hub is exceeded, it can be replaced with one that has a larger number of ports to plug lines into.
4. Provide for centralised monitoring and management of the network.
5. Single computer failure do not necessarily bring down the whole star network.
Disadvantages of Star Topology:
1. If the central hub fails, the whole network fails to operate.
2. It cost more to cable a star network.
3. Require dedicated server and NOS
Appropriateness of Star Topology:
- It must be easy to add or remove client computer.
- It must be easy to troubleshoot.
- The network is large.
- The network is expected to grow in the future.
Ring Topology:
- In a ring topology, each computer is connected directly to the next computer in line, forming a circle of cable.
- It uses token to pass the information from one computer to another.
- Every computer is connected to the next compute in the ring, and each retransmit what it receives from the previous computer.
- The message flow around the ring in one direction.
- Ring is an active topology.
- There is no termination because there is no end to the ring
Token Passing method:
Token passing a method of sending data in a ring topology
A small packet, called the token passed around the ring to each computer in tern
If a computer has information to send, it modifies the token, adds address information and the data and sends it down the ring.
The information travels around the ring until it either reaches its destination or returns to the sender.
A token can circle a ring 200 meters in diameter at about 10,000 times a second.
Advantages of Ring Topology:
1. All the computers have equal access to the network.
2. Even with many users, network performance is even
3. Allows error checking, and acknowledgement.
Disadvantages of Ring Topology:
1. Failure of one computer can affect the whole network.
2. It is difficult to troubleshoot the ring network.
3. Adding or removing computers disturbs the network.
Appropriateness of Ring Topology:
- The network must operate reasonably under a heavy load
- A higher-speed network is required.
- The network will not be frequently reconfigured.
Mesh Topology:
- In a mesh topology, every devices has a dedicated point to point link to every other device.
- A fully connected mesh network therefore has n(n-1)/2 physical channels to link n devices.
- To accommodate that many links, every device on the network must have n-1 input/output ports.
Advantages of Mesh Topology:
1. Because of the dedicated link, no traffic between computers.
2. Failure of one node computer not affect rest of the network.
3. Because of the dedicated link privacy and security are guaranteed
4. Point to point links make fault identification and fault isolation easy.
Disadvantages of Mesh Topology:
1. Due to the amount of cabling and number of input output ports, it is expensive.
2. Large space is require to run the cables.
Variations of the Major Topologies:
1. Hybrid Star:
A star network can be extended by placing another star hub where a computer might otherwise go, allowing several more computers or hubs to be connected to that hub.
2. Star Bus:
The star bus topology combine the bus and the star, linking several star hubs together with bus trunks. If one computer fails, the hub can detect the fault and isolate the computer.
If a hub fails, computers connected to it will not be able to communicate, and the bus network will be broken into two segments that can not reach each other.
3. Hybrid Topologies:
Often a network combines several topologies as subnetworks linked together is a large topology.
For instance one department of business may have decided to use a bus topology while another department has a ring.
The two can be connected to each other a central controller in a star topology
When two or more topologies are connected together it forms a hybrid topology
Sunday, July 25, 2010
Nature and Types of Software
Software - is the collection of computer programs and related data that provide the instructions telling a computer what to do.
There are two types of software:
1. Systems software: the operating system.
2. Applications software: the programs we use.
Systems software:
is the control software that operates the hardware and allows the applications to run.
Operating Systems:
- Operating Systems run in the background without the users being aware of it.
- It controls the inputs, outputs, interrupts, and storage of files as requested by the applications software.
- examples is the windows XP operating System
Efficient Management of the Computer Resources:
1. Managing memory, i.e. allocating memory to more than one program running simultaneously. Some files may get moved to the hard drive temporarily. The place on the hard drive is stored in a directory for fast access when needed again.
2.Interrupts, for Enter, Printer out of paper, or a hardware or software malfunction.
3.Diagnostic checks on the system on Boot up, sending error messages where necessary.
4.Selecting and controlling peripheral devices through small Driver programs.
Utility Programs:
Systems software include other utility programs such as:
1. Systems software include other utility programs.
2. Virus checking and cleaning.
3. Security using identification and passwords.
4. File and hard disk management for efficiency and storage.
5. Customising the computer to the users requirements, i.e. short cut menus from mouse click.
6. Setting peripheral devices to the users requirements, i.e. setting the monitor resolution.
Types of Operating Systems:
1. Command driven: DOS.
- the user has to type in the command
- it has to be in the correct syntax, errors were common
- more adaptable than Windows when used by an experienced user.
2. Windows, Icons, Mouse and Pull down menus.
- originally developed by Apple for the Macintosh
- later developed by Microsoft for Windows 3.1.
- uses a mouse to click onto an icon to navigate to programs and files.
Applications Software:
Used for a specific purpose or application:
- Word processing;
- Numerical analysis and storage;
- Recording of data;
- Designing and graphics;
- Image processing;
- Presentations;
- Desk top publishing;
- Web design.
Three Groups of application Software:
1. Generic:
- general purpose for business;
- most common applications are Word Processing, Spreadsheet & Database.
- Most generic software for business comes in an integrated package such as: Microsoft Office, Lotus Smart-Suite, Coral Draw.
- The cost of the integrated package is much less than the sum of the separate applications.
- Microsoft Office is the most popular package used in business, it contains the applications: Word, Excel, Access, Power-Point, Front-Page.
2. Bespoke:
- tailor made, specifically written for a specific application.
- Software that is specially written for an application.
- An expensive but a perfect solution to a requirement when there is no suitable package available.
- Often a one off piece of software written for a large organisation as a perfect match to their needs.
3. Specific Task:
particular tasks for business;
most common are payroll, CAD, and stock control.
Appropriate Software Packages:
1. In business the software needs are most important and the hardware is purchased to accommodate the applications.
2. If the hardware is already in place, the software has to be able to run on it.
3. Is the cost within budget?
4. Should it be evaluated for appropriate use?
5. What problems did other users have?
6. Does it contain any known bugs?
7. Is it easy to install and get up and running?
8. What technical support comes with it, is any training available, is there good documentation?
9. What are the details of the licence agreement?
There are two types of software:
1. Systems software: the operating system.
2. Applications software: the programs we use.
Systems software:
is the control software that operates the hardware and allows the applications to run.
Operating Systems:
- Operating Systems run in the background without the users being aware of it.
- It controls the inputs, outputs, interrupts, and storage of files as requested by the applications software.
- examples is the windows XP operating System
Efficient Management of the Computer Resources:
1. Managing memory, i.e. allocating memory to more than one program running simultaneously. Some files may get moved to the hard drive temporarily. The place on the hard drive is stored in a directory for fast access when needed again.
2.Interrupts, for Enter, Printer out of paper, or a hardware or software malfunction.
3.Diagnostic checks on the system on Boot up, sending error messages where necessary.
4.Selecting and controlling peripheral devices through small Driver programs.
Utility Programs:
Systems software include other utility programs such as:
1. Systems software include other utility programs.
2. Virus checking and cleaning.
3. Security using identification and passwords.
4. File and hard disk management for efficiency and storage.
5. Customising the computer to the users requirements, i.e. short cut menus from mouse click.
6. Setting peripheral devices to the users requirements, i.e. setting the monitor resolution.
Types of Operating Systems:
1. Command driven: DOS.
- the user has to type in the command
- it has to be in the correct syntax, errors were common
- more adaptable than Windows when used by an experienced user.
2. Windows, Icons, Mouse and Pull down menus.
- originally developed by Apple for the Macintosh
- later developed by Microsoft for Windows 3.1.
- uses a mouse to click onto an icon to navigate to programs and files.
Applications Software:
Used for a specific purpose or application:
- Word processing;
- Numerical analysis and storage;
- Recording of data;
- Designing and graphics;
- Image processing;
- Presentations;
- Desk top publishing;
- Web design.
Three Groups of application Software:
1. Generic:
- general purpose for business;
- most common applications are Word Processing, Spreadsheet & Database.
- Most generic software for business comes in an integrated package such as: Microsoft Office, Lotus Smart-Suite, Coral Draw.
- The cost of the integrated package is much less than the sum of the separate applications.
- Microsoft Office is the most popular package used in business, it contains the applications: Word, Excel, Access, Power-Point, Front-Page.
2. Bespoke:
- tailor made, specifically written for a specific application.
- Software that is specially written for an application.
- An expensive but a perfect solution to a requirement when there is no suitable package available.
- Often a one off piece of software written for a large organisation as a perfect match to their needs.
3. Specific Task:
particular tasks for business;
most common are payroll, CAD, and stock control.
Appropriate Software Packages:
1. In business the software needs are most important and the hardware is purchased to accommodate the applications.
2. If the hardware is already in place, the software has to be able to run on it.
3. Is the cost within budget?
4. Should it be evaluated for appropriate use?
5. What problems did other users have?
6. Does it contain any known bugs?
7. Is it easy to install and get up and running?
8. What technical support comes with it, is any training available, is there good documentation?
9. What are the details of the licence agreement?
Sunday, July 11, 2010
CLASSIFICATION OF COMPUTERS ACCORDING TO SIZE,TECHNOLOGY AND PURPOSE
According to size
• Supercomputers
• Mainframe Computers
• Minicomputers
• Workstations
• Microcomputers, or Personal Computers
Supercomputers :
are widely used in scientific applications such as aerodynamic design simulation, processing of geological data.
• Supercomputers are the most powerful computers. They are used for problems requiring complex calculations.
• Because of their size and expense, supercomputers are relatively rare.
• Supercomputers are used by universities, government agencies, and large businesses.
Mainframe Computers:
are usually slower, less powerful and less expensive than supercomputers. A technique that allows many people at terminals, to access the same computer at one time is called time sharing. Mainframes are used by banks and many business to update inventory etc.
• Mainframe computers can support hundreds or thousands of users, handling massive amounts of input, output, and storage.
• Mainframe computers are used in large organizations where many users need access to shared data and programs.
• Mainframes are also used as e-commerce servers, handling transactions over the Internet.
Minicomputers:
are smaller than mainframe, general purpose computers, and give computing power without adding the prohibitive expenses associated with larger systems. It is generally easier to use.
• Minicomputers usually have multiple terminals.
• Minicomputers may be used as network servers and Internet servers.
Workstations
• Workstations are powerful single-user computers.
• Workstations are used for tasks that require a great deal of number-crunching power, such as product design and computer animation.
• Workstations are often used as network and Internet servers.
Microcomputers, or Personal Computers :
is the smallest, least expensive of all the computers. Micro computers have smallest memory and less power, are physically smaller and permit fewer peripherals to be attached.
• Microcomputers are more commonly known as personal computers. The term “PC” is applied to IBM-PCs or compatible computers.
• Desktop computers are the most common type of PC.
• Notebook (laptop) computers are used by people who need the power of a desktop system, but also portability.
• Handheld PCs (such as PDAs) lack the power of a desktop or notebook PC, but offer features for users who need limited functions and small size.
Personal Computers(PC):
According to Technology
• Analog Computers
• Digital Computers
• Hydride Computers
Analog Computers:
These computers recognize data as a continuous measurement of a physical property ( voltage, pressure, speed and temperature).
Example: Automobile speedometer
Digital Computers:
These are high speed programmable electronic devices that perform mathematical calculations, compare values and store results. They recognize data by counting discrete signal representing either a high or low voltage state of electricity.
Hybrid Computers:
A computer that processes both analog and digital data.
According to Purpose
1. General purpose Computers
2. Special Computers
General purpose Computers
A ‘General Purpose Computer’ is a machine that is capable of carrying out some general data processing under program control.
Refers to computers that follow instructions, thus virtually all computers from micro to mainframe are general purpose. Even computers in toys, games and single-function devices follow instructions in their built-in program.
Special purpose Computers
A computer that is designed to operate on a restricted class of problems.
Use special purpose computer equipment to obtain patient diagnostic information.
reference: http://wasaa.wordpress.com/2008/06/22/classification-of-computers/
• Supercomputers
• Mainframe Computers
• Minicomputers
• Workstations
• Microcomputers, or Personal Computers
Supercomputers :
are widely used in scientific applications such as aerodynamic design simulation, processing of geological data.
• Supercomputers are the most powerful computers. They are used for problems requiring complex calculations.
• Because of their size and expense, supercomputers are relatively rare.
• Supercomputers are used by universities, government agencies, and large businesses.
Mainframe Computers:
are usually slower, less powerful and less expensive than supercomputers. A technique that allows many people at terminals, to access the same computer at one time is called time sharing. Mainframes are used by banks and many business to update inventory etc.
• Mainframe computers can support hundreds or thousands of users, handling massive amounts of input, output, and storage.
• Mainframe computers are used in large organizations where many users need access to shared data and programs.
• Mainframes are also used as e-commerce servers, handling transactions over the Internet.
Minicomputers:
are smaller than mainframe, general purpose computers, and give computing power without adding the prohibitive expenses associated with larger systems. It is generally easier to use.
• Minicomputers usually have multiple terminals.
• Minicomputers may be used as network servers and Internet servers.
Workstations
• Workstations are powerful single-user computers.
• Workstations are used for tasks that require a great deal of number-crunching power, such as product design and computer animation.
• Workstations are often used as network and Internet servers.
Microcomputers, or Personal Computers :
is the smallest, least expensive of all the computers. Micro computers have smallest memory and less power, are physically smaller and permit fewer peripherals to be attached.
• Microcomputers are more commonly known as personal computers. The term “PC” is applied to IBM-PCs or compatible computers.
• Desktop computers are the most common type of PC.
• Notebook (laptop) computers are used by people who need the power of a desktop system, but also portability.
• Handheld PCs (such as PDAs) lack the power of a desktop or notebook PC, but offer features for users who need limited functions and small size.
Personal Computers(PC):
- Desk Top
- Lap Top
- Palm Top
- PDA
According to Technology
• Analog Computers
• Digital Computers
• Hydride Computers
Analog Computers:
These computers recognize data as a continuous measurement of a physical property ( voltage, pressure, speed and temperature).
Example: Automobile speedometer
Digital Computers:
These are high speed programmable electronic devices that perform mathematical calculations, compare values and store results. They recognize data by counting discrete signal representing either a high or low voltage state of electricity.
Hybrid Computers:
A computer that processes both analog and digital data.
According to Purpose
1. General purpose Computers
2. Special Computers
General purpose Computers
A ‘General Purpose Computer’ is a machine that is capable of carrying out some general data processing under program control.
Refers to computers that follow instructions, thus virtually all computers from micro to mainframe are general purpose. Even computers in toys, games and single-function devices follow instructions in their built-in program.
Special purpose Computers
A computer that is designed to operate on a restricted class of problems.
Use special purpose computer equipment to obtain patient diagnostic information.
reference: http://wasaa.wordpress.com/2008/06/22/classification-of-computers/
Computer Hardware General Overview
Hardware: The internal structure of computers, how they operate and how they are used in solving problems.
Programming -is about Software…why do we have to learn about Hardware and other stuff? Because we as computer students will be future doctors of computers and it is very essential to learn all about computers.
What is a Computer System?
What is it comprise of?
How would you define it?
Computer System is composed of two major factors.
1. Hardware
2. Software
Hardware=The physical components (electrical circuits) that make up the computer
Software=The computer programs (sequences of instructions) that tell the computer what to do in response to a command or some event.
Components of a Computer
INPUT DEVICES - For reading data into Main Memory
PROCESSOR - For processing the data
MAIN MEMORY - The program currently being executed is stored here.(it is divided into storage units called BYTES)
AUXILIARY STORAGE - For permanent storage of programs and data
OUTPUT DEVICES - For printing, displaying Or out-put of info
Think of the Brain (System)
1. INPUT - Study for exam
2. PROCESS - Understand and memorize information
3. OUTPUT - Results of the exam
Computer Systems are the same
Data is INPUT
Data is PROCESSED
Something is OUTPUT
*GIGO (Garbage in…Garbage out..)
Types of Computer:
1. Microcomputer
2. Minicomputers
3. Mainframe Computers
4. Supercomputers
Minicomputers:
- Multi-user systems
- 100’s of workstations or terminals attached to central minicomputer
- E.g. EPOS (Electronic Point of Sale) Systems
Mainframe computers
- Large Organisations –banks, building societies, airlines, governments
- May have 1000’s of terminals –geographically remote locations
- Could occupy a whole site
- 100’s of disk drives & hardware units
- Location often kept secret! (terrorist attacks)
Supercomputers
- Largest Category of computer
- Cost Millions
- Mostly used by scientific and industrial research departments
- NASA –government agencies
- Weather Centres
- Stock Exchanges
- Large Commercial Organisations
The processor:
- PROCESSES!
- Faster the processor, better the PC?
Brain of the computer
- Processes instructions
THREE STEPS:
1) Fetches Instructions
2) Decodes Instruction
3) Executes Instruction
CHIP:
A computer chip is an electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a thin substrate of semiconductor material.
An electric circuit is made from different electrical components such as transistors, resistors, capacitors and diodes, that are connected to each other in different ways. These components have different behaviors.
The transistor acts like a switch
Resistor –resists electricity –so you can control current
Capacitor –controls electricity
Diode –also allows control of current and flow
Why Integrated Circuits (transistors)?
- Before –there were VACUUM TUBE
- They were huge
–costly
–bulky
–easily burned out
- The first Computer –ENIAC –huge 30 ton monster! *use of 18000 or so vacuum tubes*
A hybrid integrated circuit is a miniaturized electronic circuit constructed of individual semiconductor devices, as well as passive components, bonded to a substrate or circuit board.
MAIN MEMORY (MM):
- The program currently being executed and the data used by the program is held in MAIN MEMORY
- MM is divided into millions of individually addressable storage units called BYTES
- One byte can hold one character Or one byte can hold a code representing something –i.e a part of a picture, or a sound, or a program instruction.
The total number of bytes in MM = The computers MEMORY SIZE.
Computer Memory Sizes:
1 KB (KB) =1024 Bytes
1 MB =1024KB
1 GB =1024MB
1Tb =1024GB (about 1 trillion bytes)
RAM and ROM:
There are two kinds of Memory:
RAM
–Random Access Memory (MM)
- (this is used for storing programs that are currently running and data that is being processed)
- Main Memory
- Stores info about applications that are open and data
- VOLATILE = When you switch off the machine, it disappears!!!
ROM
–Read Only Memory
- (its contents are PERMANENTLY etched into the memory chip at the manufacturing stage. It is used –for example –to load the bootstrap loader (the program that loads as soon as you start the machine)
- Non-Volatile (does not change)
- Programs that are necessary for the computer to run
- Boot up program
- stores files and programs.
Cache Memory
- This is a very FAST type of memory that is used to improve the spped of a computer, DOUBLING it ….in some cases.
- Acts as an intermediate store between CPU and MM
- It works by storing most frequently or recently used instructions so that it is fast to retrive them again.
- Cache is usually between 1KB and 512KB
Disk Storage:
- Auxiliary storage is also called
- SECONDARY MEMORY
- BACKING STORE
- EXTERNAL MEMORY
- The most common secondary memory (auxiliary storage) is DISK!
Other types of Storage:
- Flash Memory Cards
- Sticks
- Floppy discs
- Disks
INPUT AND OUTPUT devices:
Input devices are the means whereby computers can accept data or instructions
Keyboards, magnetic strip cards, smart cards, magnetic ink character recognition devices,
Output –printer, VDU monitors, speakers, etc
Embedded Computers and special-purpose computers:
Not necessarily all computers are general purpose compuers with a screen, keyboard and disk drive. Special-purpose or dedicated computers can do all sorts of things from controlling the temperature in a greenhouse to controlling traffic lights or using a cash point. Embedded Computers are used in household goods automobiles and in industry
Programming -is about Software…why do we have to learn about Hardware and other stuff? Because we as computer students will be future doctors of computers and it is very essential to learn all about computers.
What is a Computer System?
What is it comprise of?
How would you define it?
Computer System is composed of two major factors.
1. Hardware
2. Software
Hardware=The physical components (electrical circuits) that make up the computer
Software=The computer programs (sequences of instructions) that tell the computer what to do in response to a command or some event.
Components of a Computer
INPUT DEVICES - For reading data into Main Memory
PROCESSOR - For processing the data
MAIN MEMORY - The program currently being executed is stored here.(it is divided into storage units called BYTES)
AUXILIARY STORAGE - For permanent storage of programs and data
OUTPUT DEVICES - For printing, displaying Or out-put of info
Think of the Brain (System)
1. INPUT - Study for exam
2. PROCESS - Understand and memorize information
3. OUTPUT - Results of the exam
Computer Systems are the same
Data is INPUT
Data is PROCESSED
Something is OUTPUT
*GIGO (Garbage in…Garbage out..)
Types of Computer:
1. Microcomputer
2. Minicomputers
3. Mainframe Computers
4. Supercomputers
Minicomputers:
- Multi-user systems
- 100’s of workstations or terminals attached to central minicomputer
- E.g. EPOS (Electronic Point of Sale) Systems
Mainframe computers
- Large Organisations –banks, building societies, airlines, governments
- May have 1000’s of terminals –geographically remote locations
- Could occupy a whole site
- 100’s of disk drives & hardware units
- Location often kept secret! (terrorist attacks)
Supercomputers
- Largest Category of computer
- Cost Millions
- Mostly used by scientific and industrial research departments
- NASA –government agencies
- Weather Centres
- Stock Exchanges
- Large Commercial Organisations
The processor:
- PROCESSES!
- Faster the processor, better the PC?
Brain of the computer
- Processes instructions
THREE STEPS:
1) Fetches Instructions
2) Decodes Instruction
3) Executes Instruction
CHIP:
A computer chip is an electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a thin substrate of semiconductor material.
An electric circuit is made from different electrical components such as transistors, resistors, capacitors and diodes, that are connected to each other in different ways. These components have different behaviors.
The transistor acts like a switch
Resistor –resists electricity –so you can control current
Capacitor –controls electricity
Diode –also allows control of current and flow
Why Integrated Circuits (transistors)?
- Before –there were VACUUM TUBE
- They were huge
–costly
–bulky
–easily burned out
- The first Computer –ENIAC –huge 30 ton monster! *use of 18000 or so vacuum tubes*
A hybrid integrated circuit is a miniaturized electronic circuit constructed of individual semiconductor devices, as well as passive components, bonded to a substrate or circuit board.
MAIN MEMORY (MM):
- The program currently being executed and the data used by the program is held in MAIN MEMORY
- MM is divided into millions of individually addressable storage units called BYTES
- One byte can hold one character Or one byte can hold a code representing something –i.e a part of a picture, or a sound, or a program instruction.
The total number of bytes in MM = The computers MEMORY SIZE.
Computer Memory Sizes:
1 KB (KB) =1024 Bytes
1 MB =1024KB
1 GB =1024MB
1Tb =1024GB (about 1 trillion bytes)
RAM and ROM:
There are two kinds of Memory:
RAM
–Random Access Memory (MM)
- (this is used for storing programs that are currently running and data that is being processed)
- Main Memory
- Stores info about applications that are open and data
- VOLATILE = When you switch off the machine, it disappears!!!
ROM
–Read Only Memory
- (its contents are PERMANENTLY etched into the memory chip at the manufacturing stage. It is used –for example –to load the bootstrap loader (the program that loads as soon as you start the machine)
- Non-Volatile (does not change)
- Programs that are necessary for the computer to run
- Boot up program
- stores files and programs.
Cache Memory
- This is a very FAST type of memory that is used to improve the spped of a computer, DOUBLING it ….in some cases.
- Acts as an intermediate store between CPU and MM
- It works by storing most frequently or recently used instructions so that it is fast to retrive them again.
- Cache is usually between 1KB and 512KB
Disk Storage:
- Auxiliary storage is also called
- SECONDARY MEMORY
- BACKING STORE
- EXTERNAL MEMORY
- The most common secondary memory (auxiliary storage) is DISK!
Other types of Storage:
- Flash Memory Cards
- Sticks
- Floppy discs
- Disks
INPUT AND OUTPUT devices:
Input devices are the means whereby computers can accept data or instructions
Keyboards, magnetic strip cards, smart cards, magnetic ink character recognition devices,
Output –printer, VDU monitors, speakers, etc
Embedded Computers and special-purpose computers:
Not necessarily all computers are general purpose compuers with a screen, keyboard and disk drive. Special-purpose or dedicated computers can do all sorts of things from controlling the temperature in a greenhouse to controlling traffic lights or using a cash point. Embedded Computers are used in household goods automobiles and in industry
Sunday, June 27, 2010
The 5 generations of computers
In the beginning ...
A generation refers to the state of improvement in the development of a product. This term is also used in the different advancements of computer technology. With each new generation, the circuitry has gotten smaller and more advanced than the previous generation before it. As a result of the miniaturization, speed, power, and memory of computers has proportionally increased. New discoveries are constantly being developed that affect the way we live, work and play.
The first generation computers were huge, slow, expensive, and often undependable. In 1946two Americans, Presper Eckert, and John Mauchly built the ENIAC electronic computer which used vacuum tubes instead of the mechanical switches of the Mark I. The ENIAC used thousands of vacuum tubes, which took up a lot of space and gave off a great deal of heat just like light bulbs do. The ENIAC led to other vacuum tube type computers like the EDVAC (Electronic Discrete Variable Automatic Computer) and the UNIVAC I (UNIVersal Automatic Computer).
The vacuum tube was an extremely important step in the advancement of computers. Vacuum tubes were invented the same time the light bulb was invented by Thomas Edison and worked very similar to light bulbs. It's purpose was to act like an amplifier and a switch. Without any moving parts, vacuum tubes could take very weak signals and make the signal stronger (amplify it). Vacuum tubes could also stop and start the flow of electricity instantly (switch). These two properties made the ENIAC computer possible.
The ENIAC gave off so much heat that they had to be cooled by gigantic air conditioners. However even with these huge coolers, vacuum tubes still overheated regularly. It was time for something new.
The transistor computer did not last as long as the vacuum tube computer lasted, but it was no less important in the advancement of computer technology. In 1947 three scientists, John Bardeen, William Shockley, and Walter Brattain working at AT&T's Bell Labs invented what would replace the vacuum tube forever. This invention was the transistor which functions like a vacuum tube in that it can be used to relay and switch electronic signals.
There were obvious differences between the transisitor and the vacuum tube. The transistor was faster, more reliable, smaller, and much cheaper to build than a vacuum tube. One transistor replaced the equivalent of 40 vacuum tubes. These transistors were made of solid material, some of which is silicon, an abundant element (second only to oxygen) found in beach sand and glass. Therefore they were very cheap to produce. Transistors were found to conduct electricity faster and better than vacuum tubes. They were also much smaller and gave off virtually no heat compared to vacuum tubes. Their use marked a new beginning for the computer. Without this invention, space travel in the 1960's would not have been possible. However, a new invention would even further advance our ability to use computers.
Transistors were a tremendous breakthrough in advancing the computer. However no one could predict that thousands even now millions of transistors (circuits) could be compacted in such a small space. The integrated circuit, or as it is sometimes referred to as semiconductor chip, packs a huge number of transistors onto a single wafer of silicon. Robert Noyce of Fairchild Corporation and Jack Kilby of Texas Instruments independently discovered the amazing attributes of integrated circuits. Placing such large numbers of transistors on a single chip vastly increased the power of a single computer and lowered its cost considerably.
Since the invention of integrated circuits, the number of transistors that can be placed on a single chip has doubled every two years, shrinking both the size and cost of computers even further and further enhancing its power. Most electronic devices today use some form of integrated circuits placed on printed circuit boards-- thin pieces of bakelite or fiberglass that have electrical connections etched onto them -- sometimes called a mother board.
These third generation computers could carry out instructions in billionths of a second. The size of these machines dropped to the size of small file cabinets. Yet, the single biggest advancement in the computer era was yet to be discovered.
This generation can be characterized by both the jump to monolithic integrated circuits(millions of transistors put onto one integrated circuit chip) and the invention of the microprocessor (a single chip that could do all the processing of a full-scale computer). By putting millions of transistors onto one single chip more calculation and faster speeds could be reached by computers. Because electricity travels about a foot in a billionth of a second, the smaller the distance the greater the speed of computers.
However what really triggered the tremendous growth of computers and its significant impact on our lives is the invention of the microprocessor. Ted Hoff, employed by Intel (Robert Noyce's new company) invented a chip the size of a pencil eraser that could do all the computing and logic work of a computer. The microprocessor was made to be used in calculators, not computers. It led, however, to the invention of personal computers, or microcomputers.
It wasn't until the 1970's that people began buying computer for personal use. One of the earliest personal computers was the Altair 8800 computer kit. In 1975 you could purchase this kit and put it together to make your own personal computer. In 1977 the Apple II was sold to the public and in 1981 IBM entered the PC (personal computer) market.
Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.
A generation refers to the state of improvement in the development of a product. This term is also used in the different advancements of computer technology. With each new generation, the circuitry has gotten smaller and more advanced than the previous generation before it. As a result of the miniaturization, speed, power, and memory of computers has proportionally increased. New discoveries are constantly being developed that affect the way we live, work and play.
The First Generation: 1946-1958 (The Vacuum Tube Years)
The first generation computers were huge, slow, expensive, and often undependable. In 1946two Americans, Presper Eckert, and John Mauchly built the ENIAC electronic computer which used vacuum tubes instead of the mechanical switches of the Mark I. The ENIAC used thousands of vacuum tubes, which took up a lot of space and gave off a great deal of heat just like light bulbs do. The ENIAC led to other vacuum tube type computers like the EDVAC (Electronic Discrete Variable Automatic Computer) and the UNIVAC I (UNIVersal Automatic Computer).
The vacuum tube was an extremely important step in the advancement of computers. Vacuum tubes were invented the same time the light bulb was invented by Thomas Edison and worked very similar to light bulbs. It's purpose was to act like an amplifier and a switch. Without any moving parts, vacuum tubes could take very weak signals and make the signal stronger (amplify it). Vacuum tubes could also stop and start the flow of electricity instantly (switch). These two properties made the ENIAC computer possible.
The ENIAC gave off so much heat that they had to be cooled by gigantic air conditioners. However even with these huge coolers, vacuum tubes still overheated regularly. It was time for something new.
The Second Generation: 1959-1964 (The Era of the Transistor)
The transistor computer did not last as long as the vacuum tube computer lasted, but it was no less important in the advancement of computer technology. In 1947 three scientists, John Bardeen, William Shockley, and Walter Brattain working at AT&T's Bell Labs invented what would replace the vacuum tube forever. This invention was the transistor which functions like a vacuum tube in that it can be used to relay and switch electronic signals.
There were obvious differences between the transisitor and the vacuum tube. The transistor was faster, more reliable, smaller, and much cheaper to build than a vacuum tube. One transistor replaced the equivalent of 40 vacuum tubes. These transistors were made of solid material, some of which is silicon, an abundant element (second only to oxygen) found in beach sand and glass. Therefore they were very cheap to produce. Transistors were found to conduct electricity faster and better than vacuum tubes. They were also much smaller and gave off virtually no heat compared to vacuum tubes. Their use marked a new beginning for the computer. Without this invention, space travel in the 1960's would not have been possible. However, a new invention would even further advance our ability to use computers.
The Third Generation: 1965-1970 (Integrated Circuits - Miniaturizing the Computer)
Transistors were a tremendous breakthrough in advancing the computer. However no one could predict that thousands even now millions of transistors (circuits) could be compacted in such a small space. The integrated circuit, or as it is sometimes referred to as semiconductor chip, packs a huge number of transistors onto a single wafer of silicon. Robert Noyce of Fairchild Corporation and Jack Kilby of Texas Instruments independently discovered the amazing attributes of integrated circuits. Placing such large numbers of transistors on a single chip vastly increased the power of a single computer and lowered its cost considerably.
Since the invention of integrated circuits, the number of transistors that can be placed on a single chip has doubled every two years, shrinking both the size and cost of computers even further and further enhancing its power. Most electronic devices today use some form of integrated circuits placed on printed circuit boards-- thin pieces of bakelite or fiberglass that have electrical connections etched onto them -- sometimes called a mother board.
These third generation computers could carry out instructions in billionths of a second. The size of these machines dropped to the size of small file cabinets. Yet, the single biggest advancement in the computer era was yet to be discovered.
The Fourth Generation: 1971-Today (The Microprocessor)
This generation can be characterized by both the jump to monolithic integrated circuits(millions of transistors put onto one integrated circuit chip) and the invention of the microprocessor (a single chip that could do all the processing of a full-scale computer). By putting millions of transistors onto one single chip more calculation and faster speeds could be reached by computers. Because electricity travels about a foot in a billionth of a second, the smaller the distance the greater the speed of computers.
However what really triggered the tremendous growth of computers and its significant impact on our lives is the invention of the microprocessor. Ted Hoff, employed by Intel (Robert Noyce's new company) invented a chip the size of a pencil eraser that could do all the computing and logic work of a computer. The microprocessor was made to be used in calculators, not computers. It led, however, to the invention of personal computers, or microcomputers.
It wasn't until the 1970's that people began buying computer for personal use. One of the earliest personal computers was the Altair 8800 computer kit. In 1975 you could purchase this kit and put it together to make your own personal computer. In 1977 the Apple II was sold to the public and in 1981 IBM entered the PC (personal computer) market.
Fifth Generation (Present and Beyond) Artificial Intelligence.
Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.
Wednesday, June 23, 2010
History of Computer
Computer History
The history of the computer owes its existence to the fact that people, who are lazy by nature, have always sought to improve their ability to calculate, in order to reduce errors and save time.
Origins: The abacus
The "abacus" was invented in the year 700; it was in use for a long time, and still is in some countries.
Then came the logarithm
The invention of the logarithm is generally credited to the Scotsman John Napier (1550-1617). In 1614, he showed that multiplication and division could be performed using a series of additions. This discovery led, in 1620, to the invention of the slide rule.
However, the true father of logarithm theory is Mohamed Ybn Moussa Al-Khawarezmi, an Arab scholar from the Persian town of Khawarezm. This scholar also developed algebra, a term which comes from the Arabic "Al-Jabr", meaning compensation, with the implication being "looking for the unknown variable X in order to compensate by balancing the results of the calculations."
The first calculating machines
In 1623, William Schickard invented the first mechanical calculating machine.
In 1642, Blaise Pascal created the arithmetic machine (called the Pascaline), a machine that could add and subtract, intended to help his father, a tax collector.
In 1673, Gottfried Wilhelm Von Leibniz added multiplication and division to the Pascaline.
In 1834, Charles Babbage invented the difference engine, which could evaluate functions.
However, once he learned that a weaving machine (called a Jacquard loom) was programmed with perforated cards, he started building a calculating machine that could take advantage of this revolutionary idea.
In 1820, the first four-function mechanical calculators debuted. They could:
• add
• subtract
• multiply
• divide
By 1885, they were being built with keyboards for entering data. Electrical motors quickly supplanted cranks.
Programmable computers
In 1938, Konrad Zuse invented a computer based around electromechanical relays: The Z3. This computer was the first to use binary instead of decimals
In 1937, Howard Aiken developed a programmable computer 17 metres long and 2.5 metres high, which could calculate 5 times faster than a human.
It was IBM's Mark I.
It was built using 3300 gears and 1400 switches linked with 800 km of electrical wiring.
In 1947, the Mark II appeared, with its predecessor's gears being replaced by electronic components.
Vacuum tube computers
In 1942, the ABC (Atanasoff Berry Computer), named after its designers, J.V. Atanasoff and C.Berry, was introduced.
In 1943, the first computer with no mechanical parts was created by J.Mauchly and J.Presper Eckert: the ENIAC (Electronic Numerical Integrator And Computer). It was made using 18000 vacuum tubes, and took up 1500 m2 of space. It was used for calculations required for designing the H-bomb.
The ENIAC's main drawback was its programming:
It could only be programmed manually, by flipping switches or plugging in cables.
The first computer error was caused by an insect, which was attracted to the vacuum tubes by the heat and became lodged in them, creating a short circuit. Thus, the name "bug" came to mean a computer error.
Indeed, as the tubes were poor conductors, they required a great deal of electrical energy, which they released as heat. This problem was solved in 1946 with the creation of the EDVAC (Electronic Discrete Variable Computer), which could store programs in memory (1024 words in central memory and 20000 words in magnetic memory).
The transistor
In 1948, the transistor was created by the firm Bell Labs (thanks to the work of the engineers John Bardeen, Walter Brattain and William Shockley). With transistors, the computers of the 1950s could be made less bulky, less energy-hungry, and therefore less expensive: This marked a turning point in computing history.
The integrated circuit
The integrated circuit was perfected in 1958 by Texas Instruments, and made even smaller and cheaper computers possible, by integrating multiple transistors on the same circuit without using electrical wiring.
The first transistor computers
In 1960, the IBM 7000 became the first transistor computer.
In 1964, the IBM 360 appeared, along with the DEC PDP-8.
Microcomputers
In 1971, the first microcomputer came out: the Kenback 1, with a 256-byte memory.
Microprocessors
In 1971, the first microprocessor, the Intel 4004, appeared. It could carry out 4 bits of operations at once.
Around the same time, Hewlett Packard put out the HP-35 calculator.
The Intel 8008 processor (which could process 8 bits at a time) was released in 1972.
In 1973, The Intel 8080 processor was used in the first microcomputers: the Micral and the Altair 8800, with 256 bytes of memory. In late 1973, Intel came out with processors that were already 10 times faster than their predecessor (the Intel 8080) and included 64 Kb of memory.
In 1976, Steve Wozniak and Steve Jobs created the Apple I in a garage. This computer had a keyboard, a 1 MHz microprocessor, 4 Kb of RAM and 1 KB of video memory.
The story goes that the two friends didn't know what to name the computer; Steve Jobs, seeing an apple tree in the garden, decided he would call the computer "apple" if he couldn't think up another name in the next five minutes.
In 1981, IBM sold the first "PC", made from an 8088 processor with a clock speed of 4.77 MHz.
Computers today
It is very difficult today to tell where computers are going. Their development has followed Moore's Law: "Every three years, four times as many transistors can be put on a chip."
This would imply that there will be 1 billion transistors on a chip around the year 2010.
http://en.kioskea.net/contents/histoire/ordinateur.php3
Computer History
Year/Enter Computer History
Inventors/Inventions Computer History
Description of Event
1936
Konrad Zuse - Z1 Computer First freely programmable computer.
1942
John Atanasoff & Clifford Berry
ABC Computer Who was first in the computing biz is not always as easy as ABC.
1944
Howard Aiken & Grace Hopper
Harvard Mark I Computer The Harvard Mark 1 computer.
1946
John Presper Eckert & John W. Mauchly
ENIAC 1 Computer 20,000 vacuum tubes later...
1948
Frederic Williams & Tom Kilburn
Manchester Baby Computer & The Williams Tube Baby and the Williams Tube turn on the memories.
1947/48
John Bardeen, Walter Brattain & Wiliam Shockley
The Transistor No, a transistor is not a computer, but this invention greatly affected the history of computers.
1951
John Presper Eckert & John W. Mauchly
UNIVAC Computer First commercial computer & able to pick presidential winners.
1953
International Business Machines
IBM 701 EDPM Computer IBM enters into 'The History of Computers'.
1954
John Backus & IBM
FORTRAN Computer Programming Language The first successful high level programming language.
1955
(In Use 1959)
Stanford Research Institute, Bank of America, and General Electric
ERMA and MICR The first bank industry computer - also MICR (magnetic ink character recognition) for reading checks.
1958
Jack Kilby & Robert Noyce
The Integrated Circuit Otherwise known as 'The Chip'
1962
Steve Russell & MIT
Spacewar Computer Game The first computer game invented.
1964
Douglas Engelbart
Computer Mouse & Windows Nicknamed the mouse because the tail came out the end.
1969
ARPAnet The original Internet.
1970
Intel 1103 Computer Memory The world's first available dynamic RAM chip.
1971
Faggin, Hoff & Mazor
Intel 4004 Computer Microprocessor The first microprocessor.
1971
Alan Shugart &IBM
The "Floppy" Disk Nicknamed the "Floppy" for its flexibility.
1973
Robert Metcalfe & Xerox
The Ethernet Computer Networking Networking.
1974/75
Scelbi & Mark-8 Altair & IBM 5100 Computers The first consumer computers.
1976/77
Apple I, II & TRS-80 & Commodore Pet Computers More first consumer computers.
1978
Dan Bricklin & Bob Frankston
VisiCalc Spreadsheet Software Any product that pays for itself in two weeks is a surefire winner.
1979
Seymour Rubenstein & Rob Barnaby
WordStar Software Word Processors.
1981
IBM
The IBM PC - Home Computer From an "Acorn" grows a personal computer revolution
1981
Microsoft
MS-DOS Computer Operating System From "Quick And Dirty" comes the operating system of the century.
1983
Apple Lisa Computer The first home computer with a GUI, graphical user interface.
1984
Apple Macintosh Computer The more affordable home computer with a GUI.
1985
Microsoft Windows Microsoft begins the friendly war with Apple.
SERIES TO BE CONTINUED
http://inventors.about.com/library/blcoindex.htm
The history of the computer owes its existence to the fact that people, who are lazy by nature, have always sought to improve their ability to calculate, in order to reduce errors and save time.
Origins: The abacus
The "abacus" was invented in the year 700; it was in use for a long time, and still is in some countries.
Then came the logarithm
The invention of the logarithm is generally credited to the Scotsman John Napier (1550-1617). In 1614, he showed that multiplication and division could be performed using a series of additions. This discovery led, in 1620, to the invention of the slide rule.
However, the true father of logarithm theory is Mohamed Ybn Moussa Al-Khawarezmi, an Arab scholar from the Persian town of Khawarezm. This scholar also developed algebra, a term which comes from the Arabic "Al-Jabr", meaning compensation, with the implication being "looking for the unknown variable X in order to compensate by balancing the results of the calculations."
The first calculating machines
In 1623, William Schickard invented the first mechanical calculating machine.
In 1642, Blaise Pascal created the arithmetic machine (called the Pascaline), a machine that could add and subtract, intended to help his father, a tax collector.
In 1673, Gottfried Wilhelm Von Leibniz added multiplication and division to the Pascaline.
In 1834, Charles Babbage invented the difference engine, which could evaluate functions.
However, once he learned that a weaving machine (called a Jacquard loom) was programmed with perforated cards, he started building a calculating machine that could take advantage of this revolutionary idea.
In 1820, the first four-function mechanical calculators debuted. They could:
• add
• subtract
• multiply
• divide
By 1885, they were being built with keyboards for entering data. Electrical motors quickly supplanted cranks.
Programmable computers
In 1938, Konrad Zuse invented a computer based around electromechanical relays: The Z3. This computer was the first to use binary instead of decimals
In 1937, Howard Aiken developed a programmable computer 17 metres long and 2.5 metres high, which could calculate 5 times faster than a human.
It was IBM's Mark I.
It was built using 3300 gears and 1400 switches linked with 800 km of electrical wiring.
In 1947, the Mark II appeared, with its predecessor's gears being replaced by electronic components.
Vacuum tube computers
In 1942, the ABC (Atanasoff Berry Computer), named after its designers, J.V. Atanasoff and C.Berry, was introduced.
In 1943, the first computer with no mechanical parts was created by J.Mauchly and J.Presper Eckert: the ENIAC (Electronic Numerical Integrator And Computer). It was made using 18000 vacuum tubes, and took up 1500 m2 of space. It was used for calculations required for designing the H-bomb.
The ENIAC's main drawback was its programming:
It could only be programmed manually, by flipping switches or plugging in cables.
The first computer error was caused by an insect, which was attracted to the vacuum tubes by the heat and became lodged in them, creating a short circuit. Thus, the name "bug" came to mean a computer error.
Indeed, as the tubes were poor conductors, they required a great deal of electrical energy, which they released as heat. This problem was solved in 1946 with the creation of the EDVAC (Electronic Discrete Variable Computer), which could store programs in memory (1024 words in central memory and 20000 words in magnetic memory).
The transistor
In 1948, the transistor was created by the firm Bell Labs (thanks to the work of the engineers John Bardeen, Walter Brattain and William Shockley). With transistors, the computers of the 1950s could be made less bulky, less energy-hungry, and therefore less expensive: This marked a turning point in computing history.
The integrated circuit
The integrated circuit was perfected in 1958 by Texas Instruments, and made even smaller and cheaper computers possible, by integrating multiple transistors on the same circuit without using electrical wiring.
The first transistor computers
In 1960, the IBM 7000 became the first transistor computer.
In 1964, the IBM 360 appeared, along with the DEC PDP-8.
Microcomputers
In 1971, the first microcomputer came out: the Kenback 1, with a 256-byte memory.
Microprocessors
In 1971, the first microprocessor, the Intel 4004, appeared. It could carry out 4 bits of operations at once.
Around the same time, Hewlett Packard put out the HP-35 calculator.
The Intel 8008 processor (which could process 8 bits at a time) was released in 1972.
In 1973, The Intel 8080 processor was used in the first microcomputers: the Micral and the Altair 8800, with 256 bytes of memory. In late 1973, Intel came out with processors that were already 10 times faster than their predecessor (the Intel 8080) and included 64 Kb of memory.
In 1976, Steve Wozniak and Steve Jobs created the Apple I in a garage. This computer had a keyboard, a 1 MHz microprocessor, 4 Kb of RAM and 1 KB of video memory.
The story goes that the two friends didn't know what to name the computer; Steve Jobs, seeing an apple tree in the garden, decided he would call the computer "apple" if he couldn't think up another name in the next five minutes.
In 1981, IBM sold the first "PC", made from an 8088 processor with a clock speed of 4.77 MHz.
Computers today
It is very difficult today to tell where computers are going. Their development has followed Moore's Law: "Every three years, four times as many transistors can be put on a chip."
This would imply that there will be 1 billion transistors on a chip around the year 2010.
http://en.kioskea.net/contents/histoire/ordinateur.php3
Computer History
Year/Enter Computer History
Inventors/Inventions Computer History
Description of Event
1936
Konrad Zuse - Z1 Computer First freely programmable computer.
1942
John Atanasoff & Clifford Berry
ABC Computer Who was first in the computing biz is not always as easy as ABC.
1944
Howard Aiken & Grace Hopper
Harvard Mark I Computer The Harvard Mark 1 computer.
1946
John Presper Eckert & John W. Mauchly
ENIAC 1 Computer 20,000 vacuum tubes later...
1948
Frederic Williams & Tom Kilburn
Manchester Baby Computer & The Williams Tube Baby and the Williams Tube turn on the memories.
1947/48
John Bardeen, Walter Brattain & Wiliam Shockley
The Transistor No, a transistor is not a computer, but this invention greatly affected the history of computers.
1951
John Presper Eckert & John W. Mauchly
UNIVAC Computer First commercial computer & able to pick presidential winners.
1953
International Business Machines
IBM 701 EDPM Computer IBM enters into 'The History of Computers'.
1954
John Backus & IBM
FORTRAN Computer Programming Language The first successful high level programming language.
1955
(In Use 1959)
Stanford Research Institute, Bank of America, and General Electric
ERMA and MICR The first bank industry computer - also MICR (magnetic ink character recognition) for reading checks.
1958
Jack Kilby & Robert Noyce
The Integrated Circuit Otherwise known as 'The Chip'
1962
Steve Russell & MIT
Spacewar Computer Game The first computer game invented.
1964
Douglas Engelbart
Computer Mouse & Windows Nicknamed the mouse because the tail came out the end.
1969
ARPAnet The original Internet.
1970
Intel 1103 Computer Memory The world's first available dynamic RAM chip.
1971
Faggin, Hoff & Mazor
Intel 4004 Computer Microprocessor The first microprocessor.
1971
Alan Shugart &IBM
The "Floppy" Disk Nicknamed the "Floppy" for its flexibility.
1973
Robert Metcalfe & Xerox
The Ethernet Computer Networking Networking.
1974/75
Scelbi & Mark-8 Altair & IBM 5100 Computers The first consumer computers.
1976/77
Apple I, II & TRS-80 & Commodore Pet Computers More first consumer computers.
1978
Dan Bricklin & Bob Frankston
VisiCalc Spreadsheet Software Any product that pays for itself in two weeks is a surefire winner.
1979
Seymour Rubenstein & Rob Barnaby
WordStar Software Word Processors.
1981
IBM
The IBM PC - Home Computer From an "Acorn" grows a personal computer revolution
1981
Microsoft
MS-DOS Computer Operating System From "Quick And Dirty" comes the operating system of the century.
1983
Apple Lisa Computer The first home computer with a GUI, graphical user interface.
1984
Apple Macintosh Computer The more affordable home computer with a GUI.
1985
Microsoft Windows Microsoft begins the friendly war with Apple.
SERIES TO BE CONTINUED
http://inventors.about.com/library/blcoindex.htm
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