Disk pack
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Disk packs and disk cartridges were early forms of
removable media Expandable storage is a form of computer storage that is designed to be inserted and removed from a system. Some forms of removable media, such as optical discs, require a reader to be installed in the computer, while others, such as USB flash dr ...
for
computer data storage Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a compute ...
, introduced in the 1960s.


Disk pack

A disk pack is a layered grouping of
hard disk platter A hard disk drive platter (or disk) is the circular disk on which magnetic data is stored in a hard disk drive. The rigid nature of the platters in a hard drive is what gives them their name (as opposed to the flexible materials which are used ...
s (circular, rigid discs coated with a magnetic data storage surface). A disk pack is the core component of a hard disk drive. In modern hard disks, the disk pack is permanently sealed inside the drive. In many early hard disks, the disk pack was a removable unit, and would be supplied with a protective canister featuring a lifting handle. The protective cover consisted of two parts, a plastic shell, with a handle in the center, that enclosed the top and sides of the disks and a separate bottom that completed the sealed package. To remove the disk pack, the drive would be taken off line and allowed to spin down. Its access door could then be opened and an empty shell inserted and twisted to unlock the disk platter from the drive and secure it to the shell. The assembly would then be lifted out and the bottom cover attached. A different disk pack could then be inserted by removing the bottom and placing the disk pack with its shell into the drive. Turning the handle would lock the disk pack in place and free the shell for removal. The first removable disk pack was invented in 1961 by IBM engineers R. E. Pattison as part of the LCF (Low Cost File) project headed by Jack Harker. The 14-inch (356 mm) diameter disks introduced by IBM became a ''de facto'' standard, with many vendors producing disk drives using 14-inch disks in disk packs and cartridges into the 1980s. Examples of disk drives that employed removable disk packs include the
IBM 1311 IBM manufactured magnetic disk storage devices from 1956 to 2003, when it sold its hard disk drive business to Hitachi. Both the hard disk drive (HDD) and floppy disk drive (FDD) were invented by IBM and as such IBM's employees were responsible fo ...
,
IBM 2311 IBM manufactured magnetic disk storage devices from 1956 to 2003, when it sold its hard disk drive business to Hitachi. Both the hard disk drive (HDD) and floppy disk drive (FDD) were invented by IBM and as such IBM's employees were responsible fo ...
, and the Digital RP04. File:Fotothek df n-10 0000117.jpg, Operator selects a disk pack File:Fotothek df n-10 0000118.jpg, Bottom cover is removed File:Fotothek df n-10 0000119.jpg, Disk pack is ready for insertion File:Disk Pack.jpg, The removable pack is in place File:IBM 1311 disk drive at CHM.jpg,
IBM 1311 IBM manufactured magnetic disk storage devices from 1956 to 2003, when it sold its hard disk drive business to Hitachi. Both the hard disk drive (HDD) and floppy disk drive (FDD) were invented by IBM and as such IBM's employees were responsible fo ...
disk drive with an extra IBM 1316 disk pack File:IBM 2314 DiskDrives and IBM 2540 CardReader Punch.jpg, IBM 2314s with removable disk packs and empty covers on top File:Data General NOVA System.jpg, Data General Nova computer with removable disk cartridge


Disk cartridge

An early disk cartridge was a single
hard disk platter A hard disk drive platter (or disk) is the circular disk on which magnetic data is stored in a hard disk drive. The rigid nature of the platters in a hard drive is what gives them their name (as opposed to the flexible materials which are used ...
encased in a protective plastic shell. When the removable cartridge was inserted into the ''cartridge drive''
peripheral device A peripheral or peripheral device is an auxiliary device used to put information into and get information out of a computer. The term ''peripheral device'' refers to all hardware components that are attached to a computer and are controlled by the ...
, the read/write heads of the drive could access the magnetic data storage surface of the platter through holes in the shell. The disk cartridge was a direct evolution from the disk pack drive, or the early
hard drive 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 with one or more rigid rapidly rotating platters coated with magne ...
. As the storage density improved, even a single platter would provide a useful amount of data storage space, with the benefit being easier to handle than a removable disk pack. An example of a cartridge drive is the IBM 2310,which used an IBM 2315 disk cartridge; see photo used on the
IBM 1130 The IBM 1130 Computing System, introduced in 1965, was IBM's least expensive computer at that time. A binary 16-bit machine, it was marketed to price-sensitive, computing-intensive technical markets, like education and engineering, succeeding th ...
. Disk cartridges were made obsolete by floppy disks.


Alignment

Disk drives with exchangeable disk packs or disk cartridges generally required the data heads to be aligned to allow packs formatted on one drive to be read and written on another compatible drive. Alignment required a special ''alignment pack'', an oscilloscope, an alignment tool that moved the read/write heads, and patience. The pattern generated on the scope looks like a row of alternating ''C'' and ''E'' characters on their backs. Head alignment needed to be performed after head replacement, and in any case on a periodic basis as part of the routine maintenance required by the drives. The alignment pack was usually called the "CE pack," because IBM never called their 'service technicians' 'repairmen,' but "Customer Engineers" (CEs). And, since the alignment pack was only to be used by CEs, it was called the "CE Pack." Special CE media was also available for tape drives and diskette drives, known as "the CE tape" and "the CE floppy." Later drives with exchangeable packs (such as the CDC 8" Lark drives) embedded the servo with the data and didn't require regular head alignment.


See also

* History of hard disk drives


References


IBM 1311 disk storage drive
IBM Archives *Thomas G. Leary, "Transporting and Protecting Cases for Drum and Disk Records," , 1965; R.E. Pattison, "Portable Memory for Data Processing Machine," , 1965 {{DEFAULTSORT:Disk Pack Rotating disc computer storage media History of computing hardware