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Apple Partition Map
Apple Partition Map (APM) is a partition scheme used to define the low-level organization of data on disks formatted for use with 68k and PowerPC Macintosh computers. It was introduced with the Macintosh II. Disks using the Apple Partition Map are divided into logical blocks, with 512 bytes usually belonging to each block. The first block, ''Block 0'', contains an Apple-specific data structure called "Driver Descriptor Map" for the Macintosh Toolbox ROM to load driver updates and patches before loading from an MFS or HFS partition. Because APM allows 32 bits worth of logical blocks, the historical size of an APM formatted disk using small blocks is limited to 2 TiB. The ''Apple Partition Map'' maps out all space used (including the map) and unused (free space) on disk, unlike the minimal x86 master boot record that only accounts for used non-map partitions. This means that every block on the disk (with the exception of the first block, ''Block 0'') belongs to a partition. So ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Partition (computing)
Disk partitioning or disk slicing is the creation of one or more regions on secondary storage, so that each region can be managed separately. These regions are called partitions. It is typically the first step of preparing a newly installed disk after a partitioning scheme is chosen for the new disk before any file system is created. The disk stores the information about the partitions' locations and sizes in an area known as the partition table that the operating system reads before any other part of the disk. Each partition then appears to the operating system as a distinct "logical" disk that uses part of the actual disk. System administrators use a program called a partition editor to create, resize, delete, and manipulate the partitions. Partitioning allows the use of different filesystems to be installed for different kinds of files. Separating user data from system data can prevent the system partition from becoming full and rendering the system unusable. Partitioning ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Extensible Firmware Interface
Unified Extensible Firmware Interface (UEFI, as an acronym) is a specification for the firmware architecture of a computing platform. When a computer is powered on, the UEFI implementation is typically the first that runs, before starting the operating system. Examples include AMI Aptio, Phoenix SecureCore, TianoCore EDK II, and InsydeH2O. UEFI replaces the BIOS that was present in the boot ROM of all personal computers that are IBM PC compatible, although it can provide backwards compatibility with the BIOS using CSM booting. Unlike its predecessor, BIOS, which is a de facto standard originally created by IBM as proprietary software, UEFI is an open standard maintained by an industry consortium. Like BIOS, most UEFI implementations are proprietary. Intel developed the original ''Extensible Firmware Interface'' (''EFI'') specification. The last Intel version of EFI was 1.10 released in 2005. Subsequent versions have been developed as UEFI by the UEFI Forum. UEFI is i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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BootX (Apple)
BootX is a software-based bootloader designed and developed by Apple Inc. for use on the company's Macintosh (now Mac) computer range. BootX is used to prepare the computer for use, by loading all required device drivers and then starting-up Mac OS X by booting the kernel on all PowerPC Macs running Mac OS X. The Intel-based Macs introduced in 2006 have a Unified Extensible Firmware Interface (UEFI) ROM, and use a UEFI-based bootloader named boot.efi rather than BootX. The program is freely available as part of the Darwin operating system under the open-source Apple Public Source License. History Older Macintoshes dating from 1983 until 1998 utilize a basic bootloader. Those Macintoshes include a ROM chip varying in sizes up to 4 megabytes (MB), which contains both the computer code to boot the computer and the Macintosh Toolbox operating system code. In 1998, with the advent of the first iMac, the firmware was updated. The ROM was reduced in size to 1 MB ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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New World ROM
New World ROM computers are Macintosh models that do not use a Macintosh Toolbox ROM on the logic board. Due to Mac OS X not requiring the availability of the Toolbox, this allowed ROM sizes to shrink dramatically (typically from to ), and facilitated the use of flash memory for system firmware instead of the now more expensive and less flexible Mask ROM that most previous Macs used. A facility for loading the Toolbox from the startup device was, however, made available, allowing the use of Mac OS 8 and Mac OS 9 on New World machines. The New World architecture was developed for the Macintosh Network Computer, an unrealized project that eventually contributed several key technologies to the first-generation iMac. All PowerPC Macs from the iMac, the iBook, the Blue and White Power Mac G3 and the Bronze Keyboard (Lombard) PowerBook G3 forward are New World ROM machines, while all previous PowerPC models (including all PCI-based Power Macs such as the Beige/Platinum Power Mac G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Checksum
A checksum is a small-sized block of data derived from another block of digital data for the purpose of detecting errors that may have been introduced during its transmission or storage. By themselves, checksums are often used to verify data integrity but are not relied upon to verify data authenticity. The procedure which generates this checksum is called a checksum function or checksum algorithm. Depending on its design goals, a good checksum algorithm usually outputs a significantly different value, even for small changes made to the input. This is especially true of cryptographic hash functions, which may be used to detect many data corruption errors and verify overall data integrity; if the computed checksum for the current data input matches the stored value of a previously computed checksum, there is a very high probability the data has not been accidentally altered or corrupted. Checksum functions are related to hash functions, fingerprints, randomization functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bootloader
A bootloader, also spelled as boot loader or called bootstrap loader, is a computer program that is responsible for booting a computer and booting an operating system. If it also provides an interactive menu with multiple boot choices then it's often called a boot manager. When a computer is turned off, its softwareincluding operating systems, application code, and dataremains stored on non-volatile memory. When the computer is powered on, it typically does not have an operating system or its loader in random-access memory (RAM). The computer first executes a relatively small program stored in the boot ROM, which is read-only memory (ROM, and later EEPROM, NOR flash) along with some needed data, to initialize hardware devices such as CPU, motherboard, memory, storage and other I/O devices, to access the nonvolatile device (usually block device, e.g., NAND flash) or devices from which the operating system programs and data can be loaded into RAM. Some earlier computer systems, u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Partition Status
Partition may refer to: Arts and entertainment Film and television * ''Partition'' (1987 film), directed by Ken McMullen * ''Partition'' (2007 film), directed by Vic Sarin * '' Partition: 1947'', or ''Viceroy's House'', a 2017 film Music * Partition (music), a segment created from a set * "Partition" (song), by Beyoncé, 2014 * ''Partition'', soundtrack to the 2007 film by Brian Tyler Law and politics * Partition (law), the division of an estate * Partition (politics), a change of political borders, including: ** Partition of India ** Partition of Ireland ** Partitions of Poland Science and technology Computing * Disk partitioning, the division of a hard disk drive * Memory partition, a memory management technique * Partition (database), the division of a logical database * Logical partition, a subset of a computer's resources, virtualized as a separate computer * Binary space partitioning, in computer science * Partition problem, in number theory and computer science Math ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Partition Type
The partition type (or partition ID) in a partition's entry in the partition table inside a master boot record (MBR) is a byte value intended to specify the file system the partition contains or to flag special access methods used to access these partitions (e.g. special CHS mappings, LBA access, logical mapped geometries, special driver access, hidden partitions, secured or encrypted file systems, etc.). Overview Lists of assigned partition types to be used in the partition table in the MBR were originally maintained by IBM and Microsoft internally. When the market of PC operating systems and disk tools grew and liberated, other vendors had a need to assign special partition types to their products as well. As Microsoft neither documented all partition types already assigned by them nor wanted to maintain foreign assignments, third parties started to simply assign partition types on their own behalf in a mostly uncoordinated trial-and-error manner. This led to various conf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Field (computer Science)
In data hierarchy, a field (data field) is a Variable (computer science), variable in a record (computer science), record. A record, also known as a data structure, allows logically related data to be identified by a single name. Identifying related data as a single group is central to the construction of understandable computer programs. The individual fields in a record may be accessed by name, just like any variable in a computer program. Each field in a record has two components. One component is the field's data type, datatype Declaration (computer programming), declaration. The other component is the field's identifier. Memory fields Fields may be stored in random access memory (RAM). The following Pascal (programming language), Pascal record definition has three field identifiers: firstName, lastName, and age. The two name fields have a datatype of an Array (data structure), array of Character (computing), character. The age field has a datatype of integer. type PersonRec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Partition Name
Partition may refer to: Arts and entertainment Film and television * ''Partition'' (1987 film), directed by Ken McMullen * ''Partition'' (2007 film), directed by Vic Sarin * '' Partition: 1947'', or ''Viceroy's House'', a 2017 film Music * Partition (music), a segment created from a set * "Partition" (song), by Beyoncé, 2014 * ''Partition'', soundtrack to the 2007 film by Brian Tyler Law and politics * Partition (law), the division of an estate * Partition (politics), a change of political borders, including: ** Partition of India ** Partition of Ireland ** Partitions of Poland Science and technology Computing * Disk partitioning, the division of a hard disk drive * Memory partition, a memory management technique * Partition (database), the division of a logical database * Logical partition, a subset of a computer's resources, virtualized as a separate computer * Binary space partitioning, in computer science * Partition problem, in number theory and computer science Math ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Big-endian
'' Jonathan_Swift.html" ;"title="Gulliver's Travels'' by Jonathan Swift">Gulliver's Travels'' by Jonathan Swift, the novel from which the term was coined In computing, endianness is the order in which bytes within a word (data type), word of digital data are transmitted over a data communication medium or Memory_address, addressed (by rising addresses) in computer memory, counting only byte significance compared to earliness. Endianness is primarily expressed as big-endian (BE) or little-endian (LE), terms introduced by Danny Cohen into computer science for data ordering in an Internet Experiment Note published in 1980. Also published at The adjective ''endian'' has its origin in the writings of 18th century Anglo-Irish writer Jonathan Swift. In the 1726 novel '' Gulliver's Travels'', he portrays the conflict between sects of Lilliputians divided into those breaking the shell of a boiled egg from the big end or from the little end. By analogy, a CPU may read a digital word ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |