Data Cycle

The data processing cycle is the order in which data is processed. There are four stages;

1. Data collection
2. Data input
3. Data processing and storage
4. Data output

ASCII Table

ASCII stands for American Standard Code for Information Interchange. It's a 7-bit character code where every single bit represents a unique character. On this webpage you will find 8 bits, 256 characters, according to ISO 8859-1 and Microsoft Windows Latin-1 increased characters, which is available in certain programs such as Microsoft Word.

ASCII control characters (character code 0-31) The first 32 characters in the ASCII-table are unprintable control codes and are used to control peripherals such as printers.

DEC OCT HEX BIN Symbol HTML Number HTML Name Description 0 000 00 00000000 NUL �   Null char 1 001 01 00000001 SOH    Start of Heading 2 002 02 00000010 STX    Start of Text 3 003 03 00000011 ETX    End of Text 4 004 04 00000100 EOT    End of Transmission 5 005 05 00000101 ENQ    Enquiry 6 006 06 00000110 ACK    Acknowledgment 7 007 07 00000111 BEL    Bell 8 010 08 00001000 BS    Back Space 9 011 09 00001001 HT 	   Horizontal Tab 10 012 0A 00001010 LF 
   Line Feed 11 013 0B 00001011 VT    Vertical Tab 12 014 0C 00001100 FF    Form Feed 13 015 0D 00001101 CR 
   Carriage Return 14 016 0E 00001110 SO    Shift Out / X-On 15 017 0F 00001111 SI    Shift In / X-Off 16 020 10 00010000 DLE    Data Line Escape 17 021 11 00010001 DC1    Device Control 1 (oft. XON) 18 022 12 00010010 DC2    Device Control 2 19 023 13 00010011 DC3    Device Control 3 (oft. XOFF) 20 024 14 00010100 DC4    Device Control 4 21 025 15 00010101 NAK    Negative Acknowledgement 22 026 16 00010110 SYN    Synchronous Idle 23 027 17 00010111 ETB    End of Transmit Block 24 030 18 00011000 CAN    Cancel 25 031 19 00011001 EM    End of Medium 26 032 1A 00011010 SUB    Substitute 27 033 1B 00011011 ESC    Escape 28 034 1C 00011100 FS    File Separator 29 035 1D 00011101 GS    Group Separator 30 036 1E 00011110 RS    Record Separator 31 037 1F 00011111 US    Unit Separator

Data Representation

Digitizing- the process of taking information and converting it into its binary form.
Bit- smallest unit of data that a computer uses
Byte- 8 bits. Is equal to 1 character.


 Technologies for storing Binary Information:
1.Magnetic
2.Optical
3.Electronic


Conversion:
1.Decimal to Hexa-Decimal
2.Decimal to Binary
3.Binary to Hexa-Decimal
4.Binary to Decimal
5.Hexa-Decimal to Decimal
6.Hexa-Decimal to Binary

MATH IS FUN!!! \m/

Machine Cycle

SEQUENCE:
1.Fetch
2.Decode
3.Execute
4.Store

Troubleshooting

1. Don't panic.
   Relax.  Take a breath. 
2. Many computer problems appear more serious than they really are.
3. It may look like the computer has crashed and all your data is lost forever. But there are a host of problems that keep you from reaching your data or the network that can be fixed, sometimes in a matter of minutes.

If it’s your computer at the school, all the documents on the “H” drive (your “My Documents folder) are saved on the server and not on the individual computers in the classroom and labs so they’re most likely still there.  Even if they’ve been saved on the “C” drive of your home computer computer, they may still be there waiting for you.

That's not to say catastrophic data loss doesn’t happen – it can, but not very often.

2. Make sure there really is a problem.
   Can't start your computer? Check the basics.
1. Examine the cables, connectors, and power cords to make sure they're plugged in securely.  Often times a loose cable or connector (power, network, keyboard, mouse, speaker, monitor cable, etc.) is the cause of the problem.
2. If you're using a power strip or a surge protector, make sure it's on and that it works. Remember that a surge protector may not be working because it is designed to self-destruct. When an electric jolt is too much, your surge protector takes the hit saving your more expensive hardware from the voltage.
3. Try plugging something else directly into the electrical outlet to make sure there isn't a power problem.
4. Check to see if your monitor is on.  Sounds silly, but it has solved my own problem more than once.

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3. Can’t get on to the network or the Internet?

1.      Check to see if anyone else around you is having a similar problem. If so, there may be a service outage affecting a wider area
2.      Check to make sure the network cable is connected to both the computer and the wall or modem. 
3.      Check where the network cable connection is made to the back of the computer, you should see a little green light right where the cable connects.  If the light isn’t on or flashing, then you are not getting a signal to the computer.  If rebooting doesn’t fix it, contact the Help Desk or your ISP.

4. Error Messages - Write them down.
1. What tipped you off to the problem? Sometimes it's an error code or message displayed on screen. Be sure to write it down — it may describe the problem and how serious it is. Be sure to document the exact wording of any error messages.  This can make the job of the Help Desk much faster. 
2. Other times you get no warning — everything just freezes. Message or no message, be sure note what was going on when the problem occurred. Were you starting your computer? Were you on the Windows Desktop? Were you in a particular application? Surfing the Web?

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5. Think about what changed recently on your computer.
   Try to pinpoint when the trouble first started. Did the problem coincide with any recent changes?
1. Did you change any settings?  If you did you might want to change them back the way they were.
2. Any peripherals been added or removed recently (such as a printer or external Memory Card reader?)
3. Has anyone else been using your computer recently?
4. Have downloaded anything off the Web?  File sharing and free MP3’s are an easy way to get a virus on your machine. 

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6. The computer is on but…

1        Everything on the screen is frozen and the keyboard and mouse are not responding. 
Try tapping on the Num Lock key.  It’s located on the right-hand side of the keyboard above the number 7. While tapping the Num Lock key, notice whether or not the Num Lock light goes on and off. If it doesn’t, the computer is completely locked up.  You’ll have to REBOOT the computer.  If the light does go off and on, wait a minute before giving up hope.  It may come back to life on its own. 
2        Pressing Alt + F4
If a software program stops working or freezes up, try pressing the ALT+F4 keys to close the window that you’re currently working in.  This can shut down a frozen window and bring the computer back to life.  If the keyboard is frozen as well, you’ll have to reboot.
 
3        The “Blue Screen” has appeared.
 
The dreaded “Blue Screen of Death”. There’s not a lot to be done except to reboot the machine.  If it keeps occurring, this is an indication of a major problem with the computer.
 
4        The computer is on, but there is no sound.
Is there a speaker icon next to the clock on the taskbar? (It’s in the lower right side of the screen)  If you can find it, double click the speaker icon to bring up the audio controls for the computer.  See if any of the volume controls have been muted or turned all the way down.  Uncheck any Mute boxes that are selected.
5        The computer is on, but the keyboard doesn’t work
Swap the keyboard or try plugging the keyboard into another computer. If it doesn't work on the other computer, there is likely something wrong with the keyboard. If it does work on the other computer, there is likely something wrong on the computer or the connection to the computer.
6        CTRL-ALT-DEL

When you press the Ctrl-Alt-Delete buttons together, you will bring up a control panel where you can select “Task Manager” and see if any of the programs are shown as “not responding”.   You may be able to shut down the offending program from there.  If you can’t get to this screen, you’ll have to reboot.
 
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7. Rebooting can do wonders.

Don’t just pull the plug!
A simple reboot may clear up the problem. Go to the Start Menu and select Shutdown. Didn't work? It's time to try a forced reboot — with, unfortunately, no way to save your work — by pressing the keys CTRL-ALT-DEL simultaneously twice in a row.
If that didn't work, you have no choice: you have to turn the computer off manually with the power switch. Hold the power button down (for  about 5 -10 seconds) and the computer will shut down.  Wait at least 10 seconds for the hard drive to stop spinning and then restart the machine.
If the computer starts up, start the applications you were using when the crash occurred. Some programs, like Microsoft Word, make timed backups of your work and may bring up recovered files. If the program notifies you that there is a “recovered document” save the file under a different name and compare them to your previously saved files.

Computer System Unit Components

1. Motherboard
A motherboard is the main printed circuit board (PCB) found in computers and other expandable systems. It holds many of the crucial electronic components of the system, such as the central processing unit (CPU) and memory, and provides connectors for other peripherals. Unlike a backplane, a motherboard contains significant sub-systems such as the processor and other components.

 

 

 

 

2. RAM

Random-access memory is a form of computer data storage. A random-access memory device allows data items to be read and written in roughly the same amount of time regardless of the order in which data items are accessed. In contrast, with other direct-access data storage media such as hard disks, CD-RWs, DVD-RWs and the older drum memory, the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement delays.

 

 

 

3. Power Box

A power supply unit (PSU) converts mains AC to low-voltage regulated DC power for the internal components of a computer. Modern personal computers universally use a switched-mode power supply. Some power supplies have a manual selector for input voltage, while others automatically adapt to the supply voltage.

 

 

 

 



4. CPU

A central processing unit (CPU) is the electronic circuitry within a computer that carries out the instructions of a computer program by performing the basic arithmetic, logical, control and input/output (I/O) operations specified by the instructions. The term has been used in the computer industry at least since the early 1960s. Traditionally, the term "CPU" refers to a processor and its control unit (CU), distinguishing these core elements of a computer from external components such as main memory and I/O circuitry.

 

 

 

5. Hard Disk

 A hard disk drive (HDD) is a data storage device used for storing and retrieving digital information using rapidly rotating disks (platters) coated with magnetic material. An HDD retains its data even when powered off. Data is read in a random-access manner, meaning individual blocks of data can be stored or retrieved in any order rather than sequentially. An HDD consists of one or more rigid ("hard") rapidly rotating disks (platters) with magnetic heads arranged on a moving actuator arm to read and write data to the surfaces.

Introduced by IBM in 1956, HDDs became the dominant secondary storage device for general-purpose computers by the early 1960s. Continuously improved, HDDs have maintained this position into the modern era of servers and personal computers. More than 200 companies have produced HDD units, though most current units are manufactured by Seagate, Toshiba and Western Digital. Worldwide disk storage revenues were US $32 billion in 2013, down 3% from 2012.



 

 

6.  Sata Cables

SATA is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives and optical drives. Serial ATA succeeded the older Parallel ATA (PATA) standard, offering several advantages over the older interface: reduced cable size and cost (seven conductors instead of 40 or 80), native hot swapping, faster data transfer through higher signalling rates, and more efficient transfer through an (optional) I/O queuing protocol.

 















 

 

7. Optical Drive

Optical disc drives are an integral part of stand-alone consumer appliances such as CD players, DVD players and DVD recorders. They are also very commonly used in computers to read software and consumer media distributed on disc, and to record discs for archival and data exchange purposes. Floppy disk drives, with capacity of 1.44 MB, have been made obsolete: optical media are cheap and have vastly higher capacity to handle the large files used since the days of floppy discs, and the vast majority of computers and much consumer entertainment hardware have optical writers. USB flash drives, high-capacity, small, and inexpensive, are suitable where read/write capability is required.

 

 

 

8. Fan

A computer fan is any fan inside, or attached to, a computer case used for active cooling, and may refer to fans that draw cooler air into the case from the outside, expel warm air from inside, or move air across a heat sink to cool a particular component.

 

 

 

 

 

9. Video Card

A video card (also called a video adapter, display card, graphics card, graphics board, display adapter, graphics adapter or frame buffer and sometimes preceded by the word discrete or dedicated to emphasize the distinction between this implementation and integrated graphics) is an expansion card which generates a feed of output images to a display (such as a computer monitor). Within the industry, video cards are sometimes called graphics add-in-boards, abbreviated as AIBs, with the word "graphics" usually omitted.

 

 

10.  Network Card

A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter, and by similar terms) is a computer hardware component that connects a computer to a computer network.







OS

An operating system (OS) is software that manages computer hardware and software resources and provides common services for computer programs. The operating system is an essential component of the system software in a computer system. Application programs usually require an operating system to function.
Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources.
For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and frequently makes a system call to an OS function or be interrupted by it. Operating systems can be found on many devices that contain a computer—from cellular phones and video game consoles to supercomputers and web servers.
Examples of popular modern operating systems include Android, BSD, iOS, Linux, OS X, QNX, Microsoft Windows, Windows Phone, and IBM z/OS. All these examples, except Windows, Windows Phone and z/OS, share roots in UNIX.