Some models have a monochrome/CGA selection switch, with a single port used for both modes. Some models have both a Monochrome and a CGA port, also with a switch to change modes (and ports). The Model D computers support a special extended graphics mode: 640x200. Leading Edge Model D (fixed-disk model) The buyer had the choice between a floppy disk model and a fixed disk (hard disk) model.
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The floppy disk model has one or two 360 KB drives, so that the user can run MS-DOS programs on the primary drive and work with files on the secondary drive, if equipped. The fixed disk model has one 360 KiB floppy drive and either a 10 MB, 20 MB, or 30 MB hard disk. The model with the 20 MB fixed disk was initially released in February 1986 at a cost of $1,895. Leading Edge dealers had difficulty keeping the 20MB model in stock.
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SPIN explored all of these approaches, and eventually delivered a 28" diameter fixed disk and a smaller multi-platter 14" removable disk-pack system. Over time, the hard disk business pioneered in SPIN became a major product line.
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Transistorized electronics improved not only the CPU (Central Processing Unit), but also the peripheral devices. The second generation disk data storage units were able to store tens of millions of letters and digits. Next to the fixed disk storage units, connected to the CPU via high-speed data transmission, were removable disk data storage units. A removable disk pack can be easily exchanged with another pack in a few seconds.
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The ER5 has a twin piston front disk brake and a rear drum brake. Unlike many modern motorcycles, with fixed caliper and floating disk, the ER5 has a fixed disk and floating caliper. 'A' models have a trailing piston which is smaller than the leading piston but the later 'C' models have identical leading and trailing pistons, dramatically improving front braking. 'A' model owners often fit caliper units from 'C' models.
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Two thin, shellacked, parallel glass disks in close proximity one to the other are vertically hinged to this axis. The larger of the two (the rear one), is a fixed disk and rests on the base along the groove of an ebonite insulation disk; the other (the front one), is a smaller mobile disk and rotates by means of a crank that controls a pair of pulleys connected by a cord. On its outer side, the fixed disk carries the inductors, two strips of tinfoil glued in the middle of two, broad paper shields placed diametrically, one beside the other. The mobile disk carries the Toepler-Voss self-excitation system consisting of six metallic buttons, each surrounded by a ring of tinfoil, placed equidistantly in a circle. Two small metal brushes rub against the buttons; the brushes are fixed to a curved conductor (covered with ebonite) that is clamped to the disks at opposite points and is in contact with the inductor’s tinfoil strips.
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In addition, each NLE system had storage limited by its fixed disk capacity. These issues were addressed by a small UK company, Eidos Interactive. Eidos chose the new ARM-based computers from the UK and implemented an editing system, launched in Europe in 1990 at the International Broadcasting Convention. Because it implemented its own compression software designed specifically for non-linear editing, the Eidos system had no requirement for JPEG hardware and was cheap to produce.
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Hibernation, also called Suspend to Disk on Linux, saves all computer operational data on the fixed disk before turning the computer off completely. On switching the computer back on, the computer is restored to its state prior to hibernation, with all programs and files open, and unsaved data intact. In contrast with standby mode, hibernation mode saves the computer's state on the hard disk, which requires no power to maintain, whereas standby mode saves the computer's state in RAM, which requires a small amount of power to maintain.
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Early in the System/36 development cycle, this was seriously improved to incorporate the folder object, which can have tremendous size, numerous extents, and contain subfolders. A library or a file must exist in a contiguous organization on one fixed disk (however, a library may contain one "extent" of roughly 50 blocks which must be reorganized, and it cannot be extended if allocated to other users). A file may be organized with an EXTEND value or it may be allocated with FILE OCL to automatically extend. All record adds/updates/deletes wait while the file is being extended.
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IBM introduced , Fixed Disk Setup Program version 1.00, with the March 1983 release of the IBM PC/XT, the first PC to store data on a hard disk, and the IBM Personal Computer DOS version 2.0. Version 1 could be used to create one FAT12 DOS partition, delete it, change the active partition, or display partition data. writes the master boot record, which supported up to four partitions. The other three were intended for other operating systems such as CP/M-86 and Xenix, which were expected to have their own partitioning utilities as did not support them.
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The CNFIGSSP procedure was used to configure the system, including the devices. Each device is assigned a two-character ID. The first letter must be alphabetic; the second must be alphameric. The system also reserved certain IDs; the device can't be called I1 or F1, for example. I1 is the name of the diskette drive; F1 is what the system calls the hard drive (stands for "fixed disk," since it is not a removable disk pack.) Use CNFIGSSP to place devices on the line/address map; identify the particular IBM printer or terminal model; assign characteristics such as console, alternate console, subconsole; and to name the printer's subconsole.
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The CNFIGSSP procedure was used to configure the system, including the devices. Each device is assigned a two-character ID. The first letter must be alphabetic; the second must be alphanumeric. The system also reserved certain IDs; you could not call your device I1 or F1, for example. I1 is the name of the diskette drive; F1 is what the system calls the hard drive (stands for "fixed disk," since it is not a removable disk pack.) CNFIGSSP is used to place devices on the line/address map; identify the particular IBM printer or terminal model; assign characteristics such as console, alternate console, subconsole; and to name the printer's subconsole.
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The signature is tested for by most System BIOSes since (at least) the IBM PC/AT (but not by the original IBM PC and some other machines). Even more so, it is also checked by most MBR boot loaders before passing control to the boot sector. Some BIOSes (like the IBM PC/AT) perform the check only for fixed disk / removable drives, while for floppies and superfloppies it is enough to start with a byte greater or equal to and the first nine words not to contain the same value, before the boot sector is accepted as valid, thereby avoiding the explicit test for , on floppies. Since old boot sectors (i.e.
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Furthermore, parameters can be passed to the Linux kernel that make it use that RAM disk as its root file system. The startup programs in that file system often cause Linux to mount another file system (perhaps on a fixed disk) and switch to using that as its root file system. loadlin operates as a separate program and does not modify the master boot record, which can be useful for situations where there are concerns about modifying the MBR (which could lead to an unbootable system if done incorrectly). Due to its structure, loadlin only works on DOS-based operating systems, and will not work on NT- based versions of Windows.
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Holtz's influence machine Between 1864 and 1880, W. T. B. Holtz constructed and described a large number of influence machines which were considered the most advanced developments of the time. In one form, the Holtz machine consisted of a glass disk mounted on a horizontal axis which could be made to rotate at a considerable speed by a multiplying gear, interacting with induction plates mounted in a fixed disk close to it. In 1865, August J. I. Toepler developed an influence machine that consisted of two disks fixed on the same shaft and rotating in the same direction. In 1868, the Schwedoff machine had a curious structure to increase the output current.
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In industry, GCIB has been used for the manufacture of semiconductor devices, optical thin films, trimming SAW and FBAR filter devices , fixed disk memory systems and for other uses. GCIB smoothing of high voltage electrodes has been shown to reduce field electron emission, and GCIB treated RF cavities are being studied for use in future high energy particle accelerators . Small argon cluster GCIB sources are increasingly used for analytical depth-profiling by secondary ion mass spectrometry (SIMS) and x-ray photoelectron spectroscopy (XPS). Argon clusters greatly reduce the damage introduced to the specimen during depth-profiling, making it practical to do so for many organic and polymeric materials for the first time.
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Similar software was developed in other countries; DIBS (a hardware and software solution) was released commercially in the UK in 1991, and Rob McKemmish released Fixed Disk Image free to Australian law enforcement. These tools allowed examiners to create an exact copy of a piece of digital media to work on, leaving the original disk intact for verification. By the end of the 1990s, as demand for digital evidence grew more advanced commercial tools such as EnCase and FTK were developed, allowing analysts to examine copies of media without using any live forensics. More recently, a trend towards "live memory forensics" has grown resulting in the availability of tools such as WindowsSCOPE.
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A disassembled and labeled 1997 HDD lying atop a mirror An overview of how HDDs work A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage and one or more rigid rapidly rotating platters coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual blocks of data can be stored and retrieved in any order. HDDs are a type of non-volatile storage, retaining stored data even when powered off.
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With the advent of larger removable and fixed disk drives, disk de-blocking formulas were employed which resulted in more disk blocks per logical file allocation block. While this allowed for larger file sizes, it also meant that the smallest file which could be allocated increased in size from 1 KB (on single-density drives) to 2 KB (on double-density drives) and so on, up to 32 KB for a file containing only a single byte. This made for inefficient use of disk space if the disk contained a large number of small files. File modification time stamps were not supported in releases up to CP/M 2.2, but were an optional feature in MP/M and CP/M 3.0.
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Prior to January 1991, pointing, data taking, and calibration of the radio telescope were controlled by a Data General Nova minicomputer ( picture ) running a custom telescope-control system. The control computer was fairly limited in speed and memory (having only 32 K byte of random access memory and 5 M byte of fixed disk storage), but it was fast enough to allow limited data reduction on-line. For further processing, all scans were transferred via 1600 bpi 9-track magnetic tape to a Digital Equipment VAXstation II/GPX workstation. In January 1991, the telescope-control functions were transferred to a Macintosh IIfx computer, running a translated and improved version of the telescope-control system written in C. Individual scans or more commonly concatenated files containing large numbers of scans can be obtained from the control computer directly over the Internet.
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For either, the BIOS reads the first physical sector of the media into RAM at absolute address , checks the signature in the last two bytes of the loaded sector, and then, if the correct signature is found, transfers control to the first byte of the sector with a jump (JMP) instruction. The only real distinction that the BIOS makes is that (by default, or if the boot order is not configurable) it attempts to boot from the first removable disk before trying to boot from the first fixed disk. From the perspective of the BIOS, the action of the MBR loading a volume boot record into RAM is exactly the same as the action of a floppy disk volume boot record loading the object code of an operating system loader into RAM. In either case, the program that the BIOS loaded is going about the work of chain loading an operating system.
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