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Commodore 4040
The Commodore 4040 is the replacement for the previous models 2040 (U.S.) and 3040 (Europe). It's a dual-drive 5¼" floppy disk subsystem for Commodore Business Machines. It uses a wide-case form, and uses the parallel IEEE-488 interface common to Commodore PET/CBM computers. These drive models use a single-density, single-side floppy data storage format similar to that used by the Commodore 1540 & 1541 drives, but with a slightly different data marker indicating which model originally formatted the disk. The low-level disk format is similar enough to allow reading between models, but different enough that one series of drive models cannot reliably write to disks formatted with one of the other model series. A difference of one extra 'header' byte is what causes this write incompatibility. The Group Coded Recording (GCR) scheme of binary encoding is used to store data on the magnetic disk medium. The drive also uses variable bit-clock to enable increased data density on a st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floppy Disk
A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a fabric that removes dust particles from the spinning disk. Floppy disks store digital data which can be read and written when the disk is inserted into a floppy disk drive (FDD) connected to or inside a computer or other device. The first floppy disks, invented and made by IBM, had a disk diameter of . Subsequently, the 5¼-inch and then the 3½-inch became a ubiquitous form of data storage and transfer into the first years of the 21st century. 3½-inch floppy disks can still be used with an external USB floppy disk drive. USB drives for 5¼-inch, 8-inch, and other-size floppy disks are rare to non-existent. Some individuals and organizations continue to use older equipment to read or transfer data from floppy disks. Floppy disk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commodore 8050
The Commodore 8050, Commodore 8250, and Commodore SFD-1001 are 5¼-inch floppy disk drives manufactured by Commodore International, primarily for its 8-bit CBM and PET series of computers. The drives offered improved storage capacities over previous Commodore drive models. Specifications All three models utilize 5¼-inch double-density floppy disks with a track spacing of 100 tracks-per-inch, for a total of 77 logical tracks per side. Data is encoded using Commodore's proprietary group coded recording scheme. Soft sectoring is used for track alignment. Like most other Commodore disk drives, these drives utilize zone bit recording to maintain an average bit density across the entire disk. Formatted capacity is approximately 0.5 megabyte per side, or 1 megabyte (1,066,496 bytes) in 4166 blocks total. The 8050 is a single-sided drive, whereas the 8250 and SFD-1001 are dual-sided drives. Dual-sided drives can fully read and write to disks formatted by single-sided drives, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zone Constant Angular Velocity
In computer storage, zone bit recording (ZBR) is a method used by disk drives to optimise the tracks for increased data capacity. It does this by placing more sectors per zone on outer tracks than on inner tracks. This contrasts with other approaches, such as ''constant angular velocity'' (CAV) -drives, where the number of sectors per track are the same. On a disk consisting of roughly concentric tracks – whether realized as separate circular tracks or as a single spiral track – the physical track length (circumference) is increased as it gets farther from the centre hub. The inner tracks are packed as densely as the particular drive's technology allows. The packing of the rest of the disks is changed depending on the type of disk. Zone recording was pioneered and patented by Chuck Peddle in 1961 while working for General Electric. With a CAV-drive the data on the outer tracks are the same angular width of those in the centre, and so less densely packed. Using ZBR instead, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constant Bit-density
Constant or The Constant may refer to: Mathematics * Constant (mathematics), a non-varying value * Mathematical constant, a special number that arises naturally in mathematics, such as or Other concepts * Control variable or scientific constant, in experimentation the unchanging or constant variable * Physical constant, a physical quantity generally believed to be universal and unchanging * Constant (computer programming), a value that, unlike a variable, cannot be reassociated with a different value * Logical constant, a symbol in symbolic logic that has the same meaning in all models, such as the symbol "=" for "equals" People * Constant (given name) * Constant (surname) * John, Elector of Saxony (1468–1532), known as John the Constant * Constant Nieuwenhuys (1920-2005), better known as Constant Places * Constant, Barbados, a populated place Arts and entertainment * "The Constant", a 2008 episode of the television show ''Lost'' * ''The Constant'' (Story of the Year a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commodore 1540
The Commodore 1540 (also known as the VIC-1540) introduced in 1982 is the companion floppy disk drive for the VIC-20 home computer. It uses single-sided 5¼" floppy disks, on which it stores roughly of data utilizing Commodore's GCR data encoding scheme. Because of the low price of both the VIC-20 and the 1540, this combination was the first computer with a disk drive to be offered on the US market for less than although the combination of the Commodore 64 and 1541 would prove more enduring. The 1540 is an "intelligent peripheral" in that it has its own MOS Technology 6502 CPU (just like its VIC-20 host) and the resident Commodore DOS on board in ROM – contrary to almost all other home computer systems of the time, where the DOS was loaded from a boot floppy and was executed on the computer's CPU. Due to a timing conflict with the C64's video chip, the C64 doesn't work properly with the 1540. The better-known 1541 is mechanically and nearly electronically identical t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commodore International
Commodore International (other names include Commodore International Limited) was an American home computer and electronics manufacturer founded by Jack Tramiel. Commodore International (CI), along with its subsidiary Commodore Business Machines (CBM), was a significant participant in the development of the home personal computer industry in the 1970s, 1980s and early 1990s. The company developed and marketed the world's best-selling computer, the Commodore 64 (1982), and released its Amiga computer line in July 1985. With quarterly sales ending 1983 of $ (equivalent to $ in ), Commodore was one of the world's largest personal computer manufacturers. History Founding and early years Commodore co-founders Jack Tramiel and Manfred Kapp met in the early 1950s while both employed by the Ace Typewriter Repair Company in New York City. In 1954, they formed a partnership to sell used and reconditioned typewriters and used their profits to purchase the Singer Typewriter Company. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commodore 1541
The Commodore 1541 (also known as the CBM 1541 and VIC-1541) is a floppy disk drive which was made by Commodore International for the Commodore 64 (C64), Commodore's most popular home computer. The best-known floppy disk drive for the C64, the 1541 is a single-sided 170-kilobyte drive for 5¼" disks. The 1541 directly followed the Commodore 1540 (meant for the VIC-20). The disk drive uses group coded recording (GCR) and contains a MOS Technology 6502 microprocessor, doubling as a disk controller and on-board disk operating system (DOS) processor. The number of sectors per track varies from 17 to 21 (an early implementation of zone bit recording). The drive's built-in disk operating system is CBM DOS 2.6. History Introduction The 1541 was priced at under at its introduction. A C64 plus a 1541 cost about $900, while an Apple II with no disk drive cost $1,295. The first 1541 drives produced in 1982 have a label on the front reading VIC-1541 and have an off-white case to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commodore 2031
The Commodore 2031 and Commodore 4031 are single-unit 5¼" floppy disk drives for Commodore International computers. They use a similar steel case form to the Commodore 9060/9090 hard disk drives, and use the parallel IEEE-488 interface common to Commodore PET/CBM computers. Essentially, both models are a single-drive version of the Commodore 2040/4040 units. The Commodore 2031LP is functionally the same as the 2031, but used the lower-profile tan case of the second version of the Commodore 1540 floppy disk drive intended for home computer use. These drive models use a single-density, single-side floppy data storage format similar to that used by the Commodore 1540 & Commodore 1541 The Commodore 1541 (also known as the CBM 1541 and VIC-1541) is a floppy disk drive which was made by Commodore International for the Commodore 64 (C64), Commodore's most popular home computer. The best-known floppy disk drive for the C64, th ... drives, but with a slightly different data m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commodore CBM-II
The Commodore CBM-II series is a short-lived range of 8-bit personal computers from Commodore Business Machines (CBM), released in 1982 and intended as a follow-on to the Commodore PET series. Technical description The CBM-II has two incarnations, the P series (P = personal, or, home use) and the B series (B = business use). The B series was available with a built-in monochrome monitor (hi-profile) with detached keyboard, and also as a single unit with built-in keyboard but no monitor (lo-profile). These machines are often referred to as the " Porsche PETs" due to incorrect rumors that the case was designed by Porsche. Though Commodore did initially consult Porsche for a case design, it proved too expensive to produce, so Commodore enlisted designer Ira Velinski to create one based on the original PET prototype. The P-series uses the VIC-II 40-column color video chip like the Commodore 64 (C64). It also includes two standard Atari-style joystick ports. The 6509 CPU runs at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floppy Disk Format
Floppy disk format and density refer to the logical and physical layout of data stored on a floppy disk. Since their introduction, there have been many popular and rare floppy disk types, densities, and formats used in computing, leading to much confusion over their differences. In the early 2000s, most floppy disk types and formats became obsolete, leaving the -inch disk, using an IBM PC compatible format of 1440 KB, as the only remaining popular format. Different floppy disk types had different recording characteristics, with varying magnetic coercivity (measured in oersteds, or in modern SI units in amperes per meter), ferrite grain size, and tracks per inch (TPI). TPI was not a part of the physical manufacturing process; it was a certification of how closely tracks of data could be spaced on the medium safely. The term density has a double meaning for floppy disks. Originally, single density and double density indicated a difference in logical encoding on the same typ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commodore PET
The Commodore PET is a line of personal computers produced starting in 1977 by Commodore International. A single all-in-one case combines a MOS Technology 6502 microprocessor, Commodore BASIC in read-only memory, keyboard, monochrome monitor, and, in early models, a cassette deck. Development of the system began in 1976, and a prototype was demonstrated at the January 1977 Consumer Electronics Show. The name "PET" was suggested by Andre Souson after he saw the Pet Rock in Los Gatos, and stated they were going to make the "pet computer". It was backronymed to Personal Electronic Transactor. A series of problems delayed production versions until December 1977, by which time the TRS-80 and Apple II had already begun deliveries. ''Byte'' referred to the three machines collectively as the "1977 trinity". Following the initial PET 2001, the design was updated through a series of models with more memory, better keyboard, larger screen, and other modifications. The systems were a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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