Storage Definitions - Part 1 - If anyone is interested?
Storage Definitions
http://www.disklabs.com/storage-definitions.asp
PART 1
Apple Talk: This is an Apple networking protocol. Data-transfer rate is 230 Kbits per second.
ASCII: American Standard Code for Information Interchange. ASCII is the universal standard for the numerical codes computers use to represent all the letters, numbers and punctuation on a computer.
ATA: Advanced Technology Attachment is the official name for what the computer industry calls Integrated Drive Electronics (IDE). This was the most common type of hard disk drive sold in desktops, and has now been superseded.
ATAPI: ATA Packet Interface. This is the defined set of commands used for devices connected to the ATA-2 that are not hard drives.
Average seek time: This is the average time required for the read/write head to move to a specific location on a hard drive or other digital media.
Bad block: This is the result of a media flaw or damaged formatting which causes the data held on a block, to be unreadable. This can cause errors which could mean that your data could be irretrievably lost, however these errors are generally small, and can also be negligible.
BIOS: Basic Input/Output System. The BIOS is run at the start up sequence when booting up a computer. It configures devices and then boots the computer up using the correct device boot sequence. The BIOS is stored on a ROM chip.
Binary: This is a two-digit numerical system known as Base 2, used by computers and digital devices to store data and complete calculations. Binary is used as it is compatible with electronics. The two digits used are 1 and 0. When this is converted into electronics, this equates to on and off.
Examples of binary numbers appear below:
0 in binary represents 0
1 represents (2^0) or 1.
10 represents (2^1) or 2.
11 represents (2^1 + 2^0) or 3.
100 represents (2^2) or 4.
101 represents (2^2 + 2^0) or 5.
110 represents (2^2 + 2^1) or 6.
111 represents (2^2 + 2^1 + 2^0) or 7.
1000 represents (2^3) or 8, and so on.
Bit: This is the smallest unit of data in a computer. A bit has a single binary value, either 0 or 1. Computers usually work in bytes which are multiples of 8 bits. They are generally designed to execute instructions and store data. The value of a bit is usually stored in a capacitor within a memory device and is stored either above or below a designated level of electrical charge.
Blu-Ray: This is a new format of optical disk. Blu-Ray was developed initially for the video recording market within High Definition Video, and is useful because of the amount of data it can hold. Blu-Ray disks can store 25Gb per disk with an option of 50Gb for double sided versions. Blu-Ray discs hold more information than other optical media because they use blue lasers. The ‘Blu(e)-Ray is actually blue/violet. This new laser uses a different, shorter wavelength than the standard red lasers used for CD’s and DVD’s, (405nm rather than 605nm), which allows the laser to focus on a smaller area, therefore much more data can be stored on the media.
Buffer: This is a section of RAM reserved for temporary storage of data waiting to be directed to a device.
Buffer Under-run: This occurs when the system cannot keep up a steady stream of data to the CD recording software. CD recorders have individual buffers that are constantly streamed with data in case of a system slowdown or interruption. It allows some ‘lee-way’ for the CD Recording software and hardware.
Byte: This is the basic unit of computer memory. It is comprised of eight bits, which each hold one character of alphanumeric data.
Cache: This is specialized RAM specifically used to optimize data transfers between system components which offer different data transfer rates.
Clean room: This is a room which has highly purified and regulated air supply designed to keep out any contamination or particulates. Some ensure a constant humidity and temperature also. There are various classes of clean room standards detailed below:
numbers (N) - Class Maximum concentration limits (particles/m^3 of air) for particles equal to and larger than the considered sizes shown below 0.1m m 0.2m m 0.3m m 0.5m m 1m m 5.0m m ISO 1 10 2 ISO 2 100 24 10 4 ISO 3 1 000 237 102 35 8 ISO 4 10 000 2 370 1 020 352 83 ISO 5 100 000 23 700 10 200 3 520 832 29 ISO 6 1 000 000 237 000 102 000 35 200 8 320 293 ISO 7 352 000 83 200 2 930 ISO 8 3 520 000 832 000 29 300 ISO 9 35 200 000 8 320 000 293 000 CDR: Compact Disk Re-writeable. This is an optical media which can be written to and erased. It is widely accepted that a standard CDR can be written to an average of 200 times before errors generally occur. CDR’s can store between 500Mb and 800Mb.
CRC: Cyclic Redundancy Check. The CRC is used as a check sum to verify the integrity of a data block. Normally, two CRC bytes are used in a data block and calculate the user data using logic chips. Mathematically, binary coefficients and polynomials are used to make up the CRC bytes which are read and then checked against the new CRC bytes from the read block whenever the data is being read back to the system.
Cylinder: The cylindrical surface formed by identical track numbers on vertically stacked discs. At any location of the head positioning arm, all tracks under all heads are the cylinder. The cylinder number is one of the three address components required to find a specific address. The other two are head number and sector number.
Disk Cache: This is a memory chip which acts as an intermediary between the hard disk drive and RAM, enabling more efficient working of the data transfer, thus making it quicker to read or write to a hard disk.
ECC: Error Correction Code. The extra parity bits in transmitted data are incorporated in order to detect errors that can be corrected by the user.
Embedded Servo: A technique in which the space between sectors, (inter-sector gaps) on each data surface of a disc is used to provide servo-positioning information. This method uses the same head to read both servo and data information, allowing all surfaces to be used for data storage.
Exabyte: Eb. This is a measure of computer data storage capacity and is ‘roughly’ quintillion bytes. An exabyte is two to the 60th power, or 1,152,921,504,606,846,976 bytes.
Storage Definitions
http://www.disklabs.com/storage-definitions.asp
PART 1
Apple Talk: This is an Apple networking protocol. Data-transfer rate is 230 Kbits per second.
ASCII: American Standard Code for Information Interchange. ASCII is the universal standard for the numerical codes computers use to represent all the letters, numbers and punctuation on a computer.
ATA: Advanced Technology Attachment is the official name for what the computer industry calls Integrated Drive Electronics (IDE). This was the most common type of hard disk drive sold in desktops, and has now been superseded.
ATAPI: ATA Packet Interface. This is the defined set of commands used for devices connected to the ATA-2 that are not hard drives.
Average seek time: This is the average time required for the read/write head to move to a specific location on a hard drive or other digital media.
Bad block: This is the result of a media flaw or damaged formatting which causes the data held on a block, to be unreadable. This can cause errors which could mean that your data could be irretrievably lost, however these errors are generally small, and can also be negligible.
BIOS: Basic Input/Output System. The BIOS is run at the start up sequence when booting up a computer. It configures devices and then boots the computer up using the correct device boot sequence. The BIOS is stored on a ROM chip.
Binary: This is a two-digit numerical system known as Base 2, used by computers and digital devices to store data and complete calculations. Binary is used as it is compatible with electronics. The two digits used are 1 and 0. When this is converted into electronics, this equates to on and off.
Examples of binary numbers appear below:
0 in binary represents 0
1 represents (2^0) or 1.
10 represents (2^1) or 2.
11 represents (2^1 + 2^0) or 3.
100 represents (2^2) or 4.
101 represents (2^2 + 2^0) or 5.
110 represents (2^2 + 2^1) or 6.
111 represents (2^2 + 2^1 + 2^0) or 7.
1000 represents (2^3) or 8, and so on.
Bit: This is the smallest unit of data in a computer. A bit has a single binary value, either 0 or 1. Computers usually work in bytes which are multiples of 8 bits. They are generally designed to execute instructions and store data. The value of a bit is usually stored in a capacitor within a memory device and is stored either above or below a designated level of electrical charge.
Blu-Ray: This is a new format of optical disk. Blu-Ray was developed initially for the video recording market within High Definition Video, and is useful because of the amount of data it can hold. Blu-Ray disks can store 25Gb per disk with an option of 50Gb for double sided versions. Blu-Ray discs hold more information than other optical media because they use blue lasers. The ‘Blu(e)-Ray is actually blue/violet. This new laser uses a different, shorter wavelength than the standard red lasers used for CD’s and DVD’s, (405nm rather than 605nm), which allows the laser to focus on a smaller area, therefore much more data can be stored on the media.
Buffer: This is a section of RAM reserved for temporary storage of data waiting to be directed to a device.
Buffer Under-run: This occurs when the system cannot keep up a steady stream of data to the CD recording software. CD recorders have individual buffers that are constantly streamed with data in case of a system slowdown or interruption. It allows some ‘lee-way’ for the CD Recording software and hardware.
Byte: This is the basic unit of computer memory. It is comprised of eight bits, which each hold one character of alphanumeric data.
Cache: This is specialized RAM specifically used to optimize data transfers between system components which offer different data transfer rates.
Clean room: This is a room which has highly purified and regulated air supply designed to keep out any contamination or particulates. Some ensure a constant humidity and temperature also. There are various classes of clean room standards detailed below:
numbers (N) - Class Maximum concentration limits (particles/m^3 of air) for particles equal to and larger than the considered sizes shown below 0.1m m 0.2m m 0.3m m 0.5m m 1m m 5.0m m ISO 1 10 2 ISO 2 100 24 10 4 ISO 3 1 000 237 102 35 8 ISO 4 10 000 2 370 1 020 352 83 ISO 5 100 000 23 700 10 200 3 520 832 29 ISO 6 1 000 000 237 000 102 000 35 200 8 320 293 ISO 7 352 000 83 200 2 930 ISO 8 3 520 000 832 000 29 300 ISO 9 35 200 000 8 320 000 293 000 CDR: Compact Disk Re-writeable. This is an optical media which can be written to and erased. It is widely accepted that a standard CDR can be written to an average of 200 times before errors generally occur. CDR’s can store between 500Mb and 800Mb.
CRC: Cyclic Redundancy Check. The CRC is used as a check sum to verify the integrity of a data block. Normally, two CRC bytes are used in a data block and calculate the user data using logic chips. Mathematically, binary coefficients and polynomials are used to make up the CRC bytes which are read and then checked against the new CRC bytes from the read block whenever the data is being read back to the system.
Cylinder: The cylindrical surface formed by identical track numbers on vertically stacked discs. At any location of the head positioning arm, all tracks under all heads are the cylinder. The cylinder number is one of the three address components required to find a specific address. The other two are head number and sector number.
Disk Cache: This is a memory chip which acts as an intermediary between the hard disk drive and RAM, enabling more efficient working of the data transfer, thus making it quicker to read or write to a hard disk.
ECC: Error Correction Code. The extra parity bits in transmitted data are incorporated in order to detect errors that can be corrected by the user.
Embedded Servo: A technique in which the space between sectors, (inter-sector gaps) on each data surface of a disc is used to provide servo-positioning information. This method uses the same head to read both servo and data information, allowing all surfaces to be used for data storage.
Exabyte: Eb. This is a measure of computer data storage capacity and is ‘roughly’ quintillion bytes. An exabyte is two to the 60th power, or 1,152,921,504,606,846,976 bytes.
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