Data Storage Devices

optical disc encodes binary data (bits) in the form of pits (binary value of 0 or off, due to lack of reflection when read) and lands (binary value of 1 or on, due to a reflection when read) on a special material (often Aluminium) on one of its flat surfaces. The encoding material sits atop a thicker substrate which makes up the bulk of the disc and forms a dust defocusing layer. The encoding pattern follows a continuous, spiral path covering the entire disc surface and extending from the innermost track to the outermost track. The data is stored on the disc with a laser or stamping machine, and can be accessed when the data path is illuminated with a laser diode in an optical disc drive.

Because alternative media won't boot with alternative operating systems.

Read only memory (ROM)

Tony Jennings did he was the first person

NAICS 334112 applies to Computer Storage Device Manufacturing.

You only need to buy one copy of any software you wish to use. Software is loaded onto the network drive, and is accessed by users 'logging-on' to individual terminals. Putting the same software on (maybe) dozens of computers would be much more expensive.

The difference between a CD Rom and a hard disk is that a CD Rom translates the information on CD's and discs. On the other hand, a hard disk stores data and useful information.

dick lick the disk till it splashes

They are considered Flash storage or elecctronically errasable got this from my thechnology in action textbook in college

a tape

You need a blank writable DVD, a DVD burner in your computer and a DVD burning software like NERO or even any free/shareware DVD burning software. In the software you need to compile a list of songs or directories which you need to burn on the DVD and then you will be ready to burn it.

There are three types of internal storage devices mainly optical, semi conductor and magnetic storage. Compact disk is an example of magnetic storage whereas silicon chip is an example of a semi conductor storage device.

There are several. The Hard Drive is probably the most robust as it does the majority of storage of data. Any internally installed plate based drive uses magnets as opposed to laser to read and write data (laser read/write drives are CD, DVD, Blu-Ray).

In addition, the computers memory card functions as a short term hard drive though I think these are not magnet based, ie putting a memory card up to a magnet will not delete all of the data.

There is no single format. Binary code is merely the representation of numeric information encoded in binary. Humans use the symbols 0 and 1 to symbolise the binary digits (bits), but computers have no notion of a number let alone the intelligence to interpret the difference between a 1 or a 0. However, binary information can be encoded in many different ways.

In the early days of computers, the computer was programmed through a front panel of switches. The computer had several modes of operation which could be configured by turning these individual switches on or off. Once a configuration was set it could be committed to the computer's memory, which effectively copied the state of these switches to a much larger set of switches laid out in a large array, where each element in the array represented a separate instruction. Once all instructions were stored, they could be executed by copying them one after the other to the instruction register, another series of switches that actually set the mode of operation. By rapidly switching from one mode to the next, the computer was able execute a sequence of very simple instructions extremely quickly.

In order to encode these instructions so that the programmer could configure the input switches correctly, the instructions were encoded in binary notation using 1s and 0s, where a 1 meant the switch was on while a 0 meant the switch was off. The early computers didn't have many instructions -- they were only capable of a handful of very simple operations -- so there were very few switches. With 4 switches we can configure the machine in exactly 16 different ways:

0000 0001 0010 0011

0100 0101 0110 0111

1000 1001 1010 1011

1100 1101 1110 1111

Each additional switch doubles the number of configurations thus if the computer has 17 to 32 instructions we would use at least 5 switches while 33 to 64 instructions would require at least 6 switches, and so on.

Each binary digit (bit) represents an increasing power of 2 where the least significant bit represents 2^0, followed by 2^1, 2^2, 2^3 and so on. This is no different to decimal notation where each digit represents an increasing power of 10 (10^0, 10^1, 10^2, 10^3 and so on). Knowing this we can easily convert from binary to decimal, such that 1101 means (from least significant to most significant digit):

1 = 1x(2^0) = 1x1 = 1

0 = 0x(2^1) = 0x2 = 0

1 = 1x(2^2) = 1x4 = 4

1 = 1x(2^3) = 1x8 = 8

1+0+4+8 = 13

Thus 1101 is the binary equivalent of 13 decimal.

If we say that 1101 represents a specific machine instruction, then we really mean instruction 13. What that instruction means to the machine depends on the machine itself -- it is a machine code and machine codes are always machine-dependent (only machines of the same type will understand what instruction 13 means). Since it represents a specific machine instruction then we call it an operation code, or an opcode for short.

Opcode 13 may require operands (one or more inputs). For instance, if opcode 13 were one of the machine's move instructions, it will need two operands: a source and a destination. These must also be encoded in binary and these codes will either represent a memory address or a CPU register, depending on the operand types expected by the opcode.

CPU registers are a bank of switches that are used to specify the inputs and outputs required by the instruction register (which is also a CPU register). Two special registers are used to keep track of the current and the next instruction. Normally, the next instruction is the one that immediately follows the current instruction in memory. However, if the current instruction is a jump instruction, the encoding in the next instruction register may change, thus allowing the computer to a make decision and possibly jump to the appropriate instruction code when the next instruction becomes the current instruction.

Of course, today, we do not program machines through a series of front panel switches. But just as we can encode the state of these switches from a numeric binary notation, we can also convert to any other binary encoding. On magnetic media we use the flux transitions between positively and negatively charged particle clusters upon a ferromagnetic material. These transitions can be "read" by a computer and decoded into a series of alternating electrical impulses which can then be encoded within an array of accumulators with high or low electrical charges each of which can be maintained by a transistor that can also independently switch the state of the accumulator.

There are no actual numbers inside a computer, of course, they are all merely the encoded representations of numbers that must be encoded, decoded and shunted from one location to another according to the machine's current opcode. For humans it is obviously easier to record the machine's "state" using numeric binary values, but this is merely an abstraction. The machine has no more concept of a number than it does of a what a human is. It is a machine -- it has no actual intelligence. It simply has a number of modes that we can configure, nothing more and nothing less. But because its native "language" is binary, we use numeric binary notation as a human convenience. It allows us to instruct the computer in the only language it knows -- including the instructions necessary to translate binary encoded information into information we can understand, whether it is decimal numbers, written words, a picture, a movie or a sound.

The capacity of the most ubiquitous floppy is 1.44 MB. Floppies in other capacities have also been made.

The standard types, just like with the CD format, are:

[ by Format type ]

DVD-ROM (pre-recorded from the factory, OR the "most standard" standard)

DVD-R (the standard blank write-once media)

DVD+R (supposed to offer superior data protection)

DVD-RW (-R rewriteable)

DVD+RW (+R rewriteable)

DVD-RAM (multiple-write sort-of like hard drive/pagefile, supported by certain DVD burners)

DVDs on a PC can be burned either all to DVD-ROM (the default option), or to "physical media type" (DVD-R, DVD+R etc.) - the availability of this latter option depends on the writer hardware and used software.

[ by Content type ]

DVD-Video

DVD-Audio

DVD-Data

[ by Physical Media type (storage space/video or audio length capability etc.) ]

Single-Side, Single-Layer (SSSL, default) - 4.7 GB

Single-Side, Double-Layer (SSDL) - 2x 4.7 GB

Dual-Side, Single-Layer (DSSL) - 2x 4.7 GB

Dual-Side, Double-Layer (DSDL) - 4x 4.7 GB

Also, note that the "video length" and similar information provided on DVDs applies and conforms to reality only, when DVD-Video (or DVD-Audio) format is used, as this forces a pre-defined encoding/compression of information (DVD-Data can store any type of information in any file format).

extended partition

some adavatages are that they are * Relitvly large in space * Removable/portable * you can find manny placces to insert them (Camras,coumputers exe..) Dissadavages are: * They Brake easy * they are not the fastest

flash memory,floppy disc,usb,pendrive,RAM,hardisk

the main role of memory is to let OS copy in it.. means when we start PC, 1st OS gets copied on ram.. it also important for software or program..

1981 by a group of scientists who found out the properties of a disc magnet

3 1/2 inch

5 1/4 inch

8 inch

Solid state Flash drives

USB Hard disks drives