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History of IBM magnetic disk drives

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 for many of the innovations in these products and their technologies. The basic mechanical arrangement of hard disk drives has not changed since the IBM 1301. Disk drive performance and characteristics are measured by the same standards now as they were in the 1950s. Few products in history have enjoyed such spectacular declines in cost and physical size along with equally dramatic improvements in capacity and performance.

IBM manufactured 8-inch floppy disk drives from 1969 until the mid-1980s, but did not become a significant manufacturer of smaller-sized, 5.25- or 3.5-inch floppy disk drives (the dimension refers to the diameter of the floppy disk, not the size of the drive). IBM always offered its magnetic disk drives for sale but did not offer them with original equipment manufacturer (OEM) terms until 1981. By 1996, IBM had stopped making hard disk drives unique to its systems and was offering all its HDDs as an OEM.

IBM uses many terms to describe its various magnetic disk drives, such as direct-access storage device (DASD), disk file and diskette file. Here, the current industry standard terms, hard disk drive (HDD) and floppy disk drive (FDD), are used.

IBM 350

The IBM 350 disk storage unit, the first disk drive, was announced by IBM as a component of the IBM 305 RAMAC computer system on September 14, 1956. Simultaneously a very similar product, the IBM 355, was announced for the IBM 650 RAMAC computer system. RAMAC stood for "Random Access Method of Accounting and Control". The first engineering prototype 350 disk storage shipped to Zellerbach Paper Company, San Francisco, in June 1956, with production shipment beginning in November 1957 with the shipment of a unit to United Airlines in Denver, Colorado.

Its design was motivated by the need for real time accounting in business. The 350 stores 5 million 6-bit characters (3.75 MB). It has fifty-two 24 in diameter disks of which 100 recording surfaces are used, omitting the top surface of the top disk and the bottom surface of the bottom disk. Each surface has 100 tracks. The disks spin at 1200 rpm. Data transfer rate is 8,800 characters per second. An access mechanism moves a pair of heads up and down to select a disk pair (one down surface and one up surface) and in and out to select a recording track of a surface pair. Several improved models were added in the 1950s. The IBM RAMAC 305 system with 350 disk storage leased for $3,200 per month. The 350 was officially withdrawn in 1969.

from the RAMAC program is generally considered to be the fundamental patent for disk drives. This first-ever disk drive was initially cancelled by the IBM Board of Directors because of its threat to the IBM punch card business but the IBM San Jose laboratory continued development until the project was approved by IBM's president.

The 350's cabinet is 60 in long, 68 in high and 29 in wide.

The RAMAC unit weighs about one ton, has to be moved around with forklifts, and was frequently transported via large cargo airplanes. According to Currie Munce, research vice president for Hitachi Global Storage Technologies (which acquired IBM's storage business), the storage capacity of the drive could have been increased beyond five million characters, but IBM's marketing department at that time was against a larger capacity drive, because they didn't know how to sell a product with more storage. Nonetheless, double capacity versions of the 350 were announced in January 1959 and shipped later the same year.

In 1984, the RAMAC 350 Disk File was designated an International Historic Landmark by The American Society of Mechanical Engineers. In 2002 at the Magnetic Disk Heritage Center, a team led by Al Hoagland began restoration of an IBM 350 RAMAC in collaboration with Santa Clara University. In 2005, the RAMAC restoration project relocated to the Computer History Museum, Mountain View, California and is now demonstrated to the public in the museum's Revolution exhibition.

IBM 353
The IBM 353, used on the IBM 7030, was similar to the IBM 1301, but with a faster transfer rate. It has a capacity of 2,097,152 (221) 64-bit words or 134,217,728 (227) bits and transferred 125,000 words per second. A prototype unit shipped in late 1960 was the first disk drive to use one head per surface flying on a layer of compressed air as in the older head design of the IBM 350 disk storage (RAMAC). Production 353s used self-flying heads essentially the same as those of the 1301.

IBM 355
The IBM 355 was announced on September 14, 1956, as an addition to the popular IBM 650. It used the mechanism of the IBM 350 with up to three access arms and stored 6 million decimal digits and 600,000 signs. It transferred a full track to and from the magnetic core memory of the 653, an IBM 650 option that included just sixty signed 10-digit words, enough for a single track of disk or a tape record, along with two unrelated features.

IBM 1405
The IBM 1405 Disk Storage Unit was announced in 1961 and was designed for use with the IBM 1400 series, medium scale business computers. The 1405 Model 1 has a storage capacity of 10 million alphanumeric characters (60,000,000 bits) on 25 disks. Model 2 has a storage capacity of 20 million alphanumeric characters (120,000,000 bits) on 50 disks. In both models the disks are stacked vertically on a shaft rotating at 1200 rpm.

Each side of each disk has 200 tracks divided into five sectors. Sectors 0–4 are on the top surface and 5–9 are on the bottom surface. Each sector holds either 178 or 200 characters. One to three forked-shaped access arms each contains two read/write heads, one for the top of the disk and the other for the bottom of the same disk. The access arms are mounted on a carriage alongside the disk array. During a seek operation an access arm moved, under electronic control, vertically to seek a disk 0–49 and then horizontally to seek a track 0–199. Ten sectors are available at each track. It takes about 10 ms to read or write a sector.

The access time ranges from 100ms to a maximum access time for model 2 of 800ms and 700ms for model 1. The 1405 model 2 disk storage unit has 100,000 sectors containing either 200 characters in move mode or 178 characters in load mode, which adds a word mark bit to each character. The Model 1 contains 50,000 sectors.

IBM 7300
The IBM 7300 Disk Storage Unit was designed for use with the IBM 7070; IBM announced a model 2 in 1959, but when IBM announced the 1301 on June 5, 1961, 7070 and 7074 customers found it to be more attractive than the 7300. The 7300 uses the same technology as the IBM 350, IBM 355 and IBM 1405

IBM 1301
The IBM 1301 Disk Storage Unit was announced on June 2, 1961 with two models. It was designed for use with the IBM 7000 series mainframe computers and the IBM 1410. The 1301 stores 28 million characters (168,000,000 bits) per module (25 million characters with the 1410). Each module has 25 large disks and 40 user recording surfaces, with 250 tracks per surface. The 1301 Model 1 has one module, the Model 2 has two modules, stacked vertically. The disks spin at 1800 rpm. Data is transferred at 90,000 characters per second.

A major advance over the IBM 350 and IBM 1405 is the use of a separate arm and head for each recording surface, with all the arms moving in and out together like a big comb. This eliminates the time needed for the arm to pull the head out of one disk and move up or down to a new disk. Seeking the desired track is also faster since, with the new design, the head will usually be somewhere in the middle of the disk, not starting on the outer edge. Maximum access time is reduced to 180 milliseconds.

The 1301 is the first disk drive to use heads that are aerodynamically designed to fly over the surface of the disk on a thin layer of air. This allows them to be much closer to the recording surface, which greatly improves performance.

The 1301 connects to the computer via the IBM 7631 File Control. Different models of the 7631 allow the 1301 to be used with a 1410 or 7000 series computer, or shared between two such computers.

The IBM 1301 Model 1 leased for $2,100 per month or could be purchased for $115,500. Prices for the Model 2 were $3,500 per month or $185,000 to purchase. The IBM 7631 controller cost an additional $1,185 per month or $56,000 to purchase. All models were withdrawn in 1970.

IBM 1302
The IBM 1302 Disk Storage Unit was introduced in September 1963. Improved recording quadrupled its capacity over that of the 1301, to 117 million 6-bit characters per module. Average access time is 165 ms and data can be transferred at 180 K characters/second, more than double the speed of the 1301. There are two access mechanisms per module, one for the inner 250 cylinders and the other for the outer 250 cylinders. As with the 1301, there is a Model 2 which doubles the capacity by stacking two modules. The IBM 1302 Model 1 leased for $5,600 per month or could be purchased for $252,000. Prices for the Model 2 were $7,900 per month or $355,500 to purchase. The IBM 7631 controller cost an additional $1,185 per month or $56,000 to purchase. The 1302 was withdrawn in February 1965.

IBM 1311

The IBM 1311 Disk Storage Drive was announced on October 11, 1962, and was designed for use with several medium-scale business and scientific computers. The 1311 is about the size and shape of a top-loading washing machine and stores 2 million characters (12,000,000 bits) (or, in so-called "Load Mode" on an IBM 1401, a sector can hold 90 7-bit characters, or 12,600,000 bits total ) on a removable IBM 1316 disk pack. Seven models of the 1311 were introduced during the 1960s. They were withdrawn during the early 1970s.

Each IBM 1316 Disk Pack is 4 in high, weighs 10 lb and contains six 14 in diameter disks, yielding 10 recording surfaces (the outer surfaces are not used). The 10 individual read/write heads are mounted on a common actuator within the disk drive which moves in and out hydraulically and is mechanically detented at the desired track before reading or writing occurs. The disks spin at 1500 rpm. Each recording surface has 100 tracks with 20 sectors per track. Each sector stores 100 characters. The disk pack is covered with a clear plastic shell and a bottom cover when not in use. A lifting handle in the top center of the cover is rotated to release the bottom cover. Then the top of the 1311 drive is opened and the plastic shell lowered into the disk-drive opening (assuming it is empty). The handle is turned again to lock the disks in place and release the plastic shell, which is then removed and the drive cover closed. The process is reversed to remove a disk pack. The same methods are used for many later disk packs.

There are seven models of the 1311 disk drive. The first drive attached to a system is a "master drive" which contains the controller and can control a number of Model 2 "slave drives."
 * 1) Master drive on an IBM 1440, IBM 1460, or IBM 1240 system and can control up to four Model 2 drives. Introduced October 11, 1962. Withdrawn February 8, 1971.
 * 2) Slave drive to a master drive. Can have any special feature incorporated that the master drive has incorporated. Introduced October 11, 1962. Withdrawn January 6, 1975.
 * 3) Master drive on IBM 1620 or IBM 1710 system and can control up to three Model 2 drives. Does not support any special features. Introduced October 11, 1962. Withdrawn May 12, 1971.
 * 4) Master drive on an IBM 1401 system and can control up to four Model 2 drives. Introduced October 11, 1962. Withdrawn February 8, 1971.
 * 5) Master drive on an IBM 1410, IBM 7010, or IBM 7740 system and can control up to four Model 2 drives. Direct Seek comes as standard on this model. Introduced January 7, 1963. Withdrawn May 12, 1971.
 * 6) No information available, probably a master drive. Introduced March 5, 1968. Withdrawn February 2, 1971.
 * 7) No information available, probably a slave drive to Model 6. Introduced March 5, 1968. Withdrawn February 2, 1971.

The optional special features are:
 * Direct Seek: Without this option every seek returns to track zero first.
 * Scan Disk: Automatic rapid search for identifier or condition.
 * Seek Overlap: Allows a seek to overlap a single read or write, and any number of other seeks, when multiple drives are in use.
 * Track Record: Increases the capacity of the disk by writing a single large record per track instead of using 20 separate sectors. A track can hold 2,980 characters in 6-bit 'Move Mode", and 2,682 7-bit characters in "Load Mode", giving the drive a total capacity of 17,880,000 bits in 6-bit mode, and 18,774,000 bits in 7-bit mode.

The master drives, Models 1, 3, 4, and 5, which contain extra power supplies and the control logic, are about a foot wider than the Model 2 slave drive.

IBM 2302
The IBM 2302 is the System/360 version of the 1302, with track formatting in accordance with S/360 DASD architecture rather than 7000 series architecture.

It uses a non-removable module of 25 platters, of which 46 surfaces are used for recording. The 2302 Model 3 contains one module and the Model 4 two. There are two independent access mechanisms per module, one for the innermost 250 cylinders, and one for the outermost 250, tracks available to each access mechanism are called an access group. The access mechanism provides one read/write head per track. Average rotational delay is 17 milliseconds (msec), and maximum is 34 msec. Maximum seek time per access group is 180 msec. The track size is 4985 bytes; with formatting information and alternate tracks, module capacity is stated as 112 MB. The 2302 attaches to IBM mainframes via a IBM 2841 Storage Control Unit.

IBM 2305
The IBM 2305 fixed head storage (a fixed-head disk drive sometimes incorrectly called a drum) and associated IBM 2835 Storage Control were announced in 1970, initially to connect to the 360/85 and 360/195 using the IBM 2880 Block Multiplexor Channel.

The 2305 Drive was in much demand when the System 370 offered Virtual Storage, and these 2305s were often used for paging devices. They were used in this way on 3155, 3165, 3158, 3168, 3033, 4341, and 3081 (with special feature microcode.) The 2305 was also used for high activity small data sets such as catalogs and job queues.

The 2305-1 has a capacity of 5.4 MB and runs at 3.0 MB/second when attached using the 2-byte channel interface. Average access time is 2.5 ms. The larger 2305-2 has a capacity of 11.2 MB and runs at 1.5 MB/second with an average access time of 5 ms.

The 2305 provides large-scale IBM computers with fast, continuous access to small-sized quantities of information. Its capacity and high data rate make it ideal for some systems residence functions, work files, job queues, indices and data sets that are used repeatedly. Its fast response time makes it attractive as a paging device in a heavily loaded systems, where there are 1.5 or more transactions per second.

IBM 2311

The IBM 2311 Disk Storage Drive was introduced with the 2841 Control Unit in 1964 for use throughout the IBM System/360; the combination was also available on the IBM 1130 and the IBM 1800. The drive also directly attaches to the IBM System/360 Model 20 and the IBM System/360 Model 25. All drives used the IBM 1316 Disk Pack introduced with the IBM 1311.

The 2311 Model 1 attaches to most IBM mainframes through a 2841 Control Unit; it attaches to the System/360 Model 25 thru a Disk Attachment Control which provides the function of the control unit. Disk packs are written in these attachments in IBM's count key data variable record length format.

The 2311 models 11 or 12 are used when attached to an integrated control of the System/360 Model 20 and the disk packs are written with a fixed sector format. The disk packs are not interchangeable between those written on the Model 1 and those written on the Models 11 or 12.

The 2311 mechanism is largely identical to the 1311, but recording improvements allow higher data density. The 2311 stores 7.25 megabytes on a single removable IBM 1316 disk pack (the same type used on the IBM 1311) consisting of six platters that rotate as a single unit. The 2311 has ten individual read/write (R/W) heads mounted on a common actuator which moves in and out hydraulically and is mechanically detented at the desired track before reading or writing occurred. Each recording surface has 200 tracks plus three optional tracks which can be used as alternatives in case faulty tracks are discovered. Average seek time is 85 ms. Data transfer rate is 156 kB/s.

Because the 2311 was to be used with a wide variety of computers within the 360 product line, its electrical interconnection was standardized. This created an opportunity for other manufacturers to sell plug compatible disk drives for use with IBM computers and an entire industry was born.

IBM 2314 Disk Access Storage Facility Model 1
The IBM 2314 Disk Access Storage Facility Model 1 was introduced on April 22, 1965, one year after the System/360 introduction. It was used with the System/360 and the System/370 lines. With the Two Channel Switch feature it could interface with two 360/370 channels. The 2314 Disk access mechanism was similar to the 2311, but further recording improvements allowed higher data density. The 2314 stored 29,176,000 characters (200×20×7294 bytes per track) on a single removable IBM 2316 disk pack which was similar in design to the 1316 but was taller as a result of increasing the number of disks from six to eleven. The 2316 disk pack containing the eleven 14 in diameter disks yielded 20 recording surfaces. The drive access consisted of 20 individual R/W heads mounted on a common actuator which was moved in and out hydraulically and mechanically detented at the desired track before reading or writing occurred. Each recording surface has 200 tracks. Access time was initially the same as the 2311, but later models were faster as a result of improvements made in the hydraulic actuator. Data transfer rate was doubled to 310 kB/s.

The original Model 1 consists nine disk drives bundled together with one price; separately shipped was a storage control unit, a single drive module, and two four drive modules for a total of nine drives. The drives are mounted in individual drawers that are unlatched and pulled out to access the disk pack. Because of their appearance they acquired the nickname of "Pizza Ovens". Only eight drives of the nine are available to the computer at any one time. The ninth drive is there for a spare for the user and can also be worked on "offline" by a Field Engineer while the other drives are in use by the customer. Each drive's system address is determined in part by a user-swappable plug, one such plug denoting a spare drive not system accessible. This permits physically changing the address of a drive by changing the plug. A 2844 Control Unit can be added to the 2314 Control Unit which allows two S/360 Channels simultaneous access to two separate disk drives in the Storage Facility.

Other 2314 models came later:

IBM 2314 direct access storage facility - A series
In 1969 IBM unbundled the facility into separate models allowing up to nine drives (eight on line) attached to a 2314 Storage Control:
 * 2312 Disk Storage, a one drive module.
 * 2313 Disk Storage, a four drive module.
 * 2318 Disk Storage, a two drive module.

IBM 2319

 * In a response to competition from plug compatible manufacturers of 2314 equivalent storage subsystems, IBM beginning 1970 introduced a series of low priced three drive module 2319s which were manufactured by removing one module from the four drive module 2313, rebranding it as a 2319 A1 and offering it at a substantially reduced rental price. This had the effect of lowering the rental price to new customers while keeping the high rental price on existing customers. The 2319-A1 attaches to integrated controllers for only the System/370 Models 135 and 145. Conventional 2314 DASD such as the 2312 or 2318 can attach to the 2319-A1
 * 2319 B series of three disk drives modules allow three, six or nine drive attachment to a new 2314 Model B Storage Control Unit.

IBM 3310
IBM introduced the IBM 3310 Direct Access Storage Device on January 30, 1979, for IBM 4331 midrange computers. Each drive had a capacity of 64.5 MB. The 3310 was a fixed-block architecture device, used on DOS/VSE and VM, the only S/370 operating systems that supported FBA devices.

IBM 3330
The IBM 3330 Direct Access Storage Facility, code-named Merlin, was introduced in June 1970 for use with the IBM System/370 and the IBM System 360/195. The original announcement included the 3330 Model 1, with two drives, and the 3330 Model 2, with only one drive. The 3330 has removable disk packs, similar to its predecessors, and the packs hold 100 MB (404×19×13,030 bytes). Access time is 30 ms and data transfers at 806 kB/s. A major advance introduced with the 3330 is the use of error correction, which makes the drives more reliable and reduces costs because small imperfections in the disk surface can be tolerated. The circuitry can correct error bursts up to 11 bits long through use of fire codes. The initial configuration consists of one storage control unit (3830 Model 1) bolted to a 3330, with optionally three more 3330's bolted together. This is known as a string, making a maximum of eight drives in a string.

In August 1972 IBM announced the 3830 Model 2 Storage Control and the 3333 Disk Storage and Control, separating the control unit from the string. The 3830 became a director type of storage control, controlling one or more strings. The now first unit of the string, the 3333 contains a controller and two drives and it can control up to three attached 3330's for a maximum of eight drives in the string as shown in the illustration. The 3830 Model 2 can connect two 3333's for a maximum of 16 drives per storage control and the 3333 optionally has a string switch that enables it to be connected to two different storage controls.

In 1973 IBM announced double density versions (-11 models) of the 3330 product line: the 3333–11, 3330-11 and the 3336–11; the 3336-11 Disk Packs hold up to 200 MB (808x19x13,030 bytes). It is not possible to mix single and double density drives within a string. It is possible to field upgrade existing 3330 Models to Model 11, but this is a major task, as the drives had to be converted, and all the existing data had to be copied to the new media.

The 3330 was withdrawn in 1983.

IBM 3340 and 3344
The IBM 3340 and 3344 have similar characteristics. However, only a 3340 can serve as head of string; there are no A model 3344 drives, and a 3344 must be attached to a 3340 A model as head of string.

IBM 3340
The IBM 3340 Direct Access Storage Facility, code-named Winchester, was introduced in March 1973 for use with IBM System/370. Three models were announced, the 3340-A2 with two drives and a controller, the models B2 (two drives) and B1 (one drive). B-units can connect to the model A2 to a maximum of eight drives.

It uses removable data modules that included the head and arm assembly; an access door of the data module opens or closes during a mechanical load/unload process to connect the data module to the drive; unlike previous disk packs and cartridges there is no cover to remove during the insertion process. Access time is 25 millisecond and data transfers at 885 kB/s. Three versions of the removable IBM 3348 Data Module were sold, one with 35 megabyte capacity, another with 70 megabytes, the third also has 70 megabytes, of which 500 kilobytes were accessible with fixed heads for faster access. The 3340 also uses error correction. It was withdrawn in 1984.

The 3340 was developed in San Jose under the leadership of Ken Haughton. Early on the design was focused on two removable 30 megabyte modules. Because of this 30/30 configuration, the code name Winchester was selected after the famous Winchester .30-30 rifle; subsequently the capacities were increased, but the code name stuck.

One significant aspect of this product, and the reason that disk drives in general became known as "Winchester technology", was that this head design was very low cost and did not require the heads to be unloaded from the media. Winchester technology allowed the head to land and take off from the disk media as the disk spun up and down. This resulted in very significant savings and a large reduction of complexity of the head and arm actuating mechanism. This head design rapidly became a standard design within the disk drive manufacturing community.

Up into the early 1990s the term Winchester or Winnie was used for hard disk drives in general long after the introduction of the 3340, but is no longer in common use in most parts of the world.

IBM 3344
The IBM 3344 is similar to the 3340, except that it uses fixed media rather than removable 3348 data modules, each spindle has four logical drives each with the capacity of a 3348–70, there is no A (head of string) model and it is only available in dual drive models. The 3344-B2F is identical to the 3344-B2 except that both drives have fixed heads over some cylinders. Both 3344-B2 and 3344-B2F require a 3340-A2 or 3340-A2F as head of string. Inside, the 3344 is exactly the same as IBM 3350, the difference is only in the microcode in the control unit.

IBM 3350
The IBM 3350 Direct Access Storage Facility, code-named Madrid, was introduced in 1975 for use with IBM System/370. Its non-removable head-disk assemblies (HDAs) are sealed and included the head and arm assembly. The 3350 disk geometry is 555 cylinders, 30 heads, and 19,069 bytes per track, which give each HDA a storage capacity of 317,498,850 bytes. Sealed HDAs were standard practice on all IBM DASD hereafter.

Disk units are identified as Models A2, A2F, B2, B2F, C2, and C2F with each model containing two HDAs. Model A2 and A2F has one additional electronic board, allowing it to be connected to the control unit. They are referred to as controllers, and also sometimes head-of-string. The models are installed in strings of units with an A2 or A2F unit, and then up to three B2 units or up to two B2s and a C2. The A2 unit usually has a string switch, allowing it to be connected to two different storage control units. This allows two I/O operations simultaneously take place to two different HDAs in the string. The storage control unit can be a 3830 Model 2, or the ISC (Integrated Storage Control) found in the 3148, 3158 or 3168 cpu's. Also later control units (3880) are backwards compatible and can be used. The C2s unit also contains a controller, that can be connected to a storage control unit and serves as a secondary path to itself and the A2 and B2 units. The C2 controller is a spare, it can only be used when the controller in the A unit is broken, and subsequently powered off. It has also limited connections, usually the A unit has a string switch, but the C unit only can be connected to one storage control unit. The valid 3350 strings are: -A, -AB, -ABB, -ABBB, -AC-, -ABC-, or -ABBC- configurations.

The "x2F", as in Model A2F, unit is a normal x2 unit, but its two HDAs also have a Fixed Head area over the first five cylinders, thereby reducing seek time to zero for these five cylinders. This fixed head area is intended to be allocated to the frequently accessed HASP or JES2 checkpoint area and thus greatly reduce head motion on the SPOOL device. The fixed head area can also be utilized for TSO swap data (MVT and SVS) and system swap data (MVS) wherein the swap data for SVS and MVS consist of blocks of pages that have been in memory when an address space is selected for swap-out; those pages need not be contiguous and in general do not include pages that have not been modified since their last page-in. This system architecture greatly improves context switches between TSO users or batch regions.

The IBM 3350 family was withdrawn in September 1994.

IBM 3370
IBM introduced the IBM 3370 Direct Access Storage Device in January 1979 for IBM 4331, 4341, and System/38 midrange computers. It has seven fixed 14 in disks, and each unit has a capacity of 571 MB. It was the first HDD to use thin-film head technology; research on that technology started at Thomas J. Watson Research Center in the late 1960s. The 3370 was a fixed-block architecture device, used on DOS/VSE and VM, the only S/370 operating systems that supported FBA devices.

IBM 3375
The sister unit was called the IBM 3375 and used count key data architecture, which was required for OS/360 and successor operating systems.

IBM 3380

The IBM 3380 Direct Access Storage Device was introduced in June 1980. It uses film head technology and has a unit capacity of 2.52 gigabytes (two hard disk assemblies each with two independent actuators each accessing 630 MB within one 3380 unit) with a data transfer rate of 3 megabytes per second. Average access time was 16 ms. Purchase price at time of introduction ranged from $81,000 to $142,200. Due to tribology problems encountered between heads and media, the first units did not ship until October 1981.

Similar to its predecessor (3350) the standard configuration is one A unit and up to three B units, but because each 3380 contains four devices each string now can contain up to 16 devices. Usually it is connected to a 3880 storage control units with two paths, allowing two simultaneous I/O operations, however, the operations must target different HDAs.

In February 1985, IBM announced a double density version – the Extended Capability Models of the 3380 (3380 E) having 5.04 gigabytes per 3380 unit, that is, two 1.26 gigabyte actuators on two hard disk assemblies.

A triple capacity version, the 3380 K was announced in August 1987 having 7.562 gigabytes per 3380 unit, that is, two 1.89 gigabyte actuators on two hard disk assemblies. The new Model K and Model J can optionally run in four-path mode. In this mode, the string has two A units located in the middle, and up to three B units connected on each side, giving a maximum of 32 devices in a string. This requires they are connected to a 3990 storage control unit, and allows four simultaneous I/O operation in the string.

There are twelve models of the IBM 3380 family: six A-units, five B-units and one C-unit. A-units (heads of string) contain additional logic to perform string controller functions and connect to IBM storage control units (3880 or 3990). The C-units connect directly to an IBM channel. B-units connects to A-units or C-units.

The last models were withdrawn by IBM in May 1996 representing a production run of 15 years; a run longer than most disk drives

IBM 3390
The IBM 3390 Direct Access Storage Device series was introduced November 1989, offering a maximum storage of up to 22 gigabytes in a string of multiple drives. Cost of a storage system varied by configuration and capacity, between $90,000 and $795,000.

A 3390 string consists of an A unit placed in the middle, and optionally one or two B units bolted to its sides. The A unit can have four or eight devices, each B unit can have up to 12 devices. The 3390 is always running in four-path mode, connected to a 3990 storage control unit. Optionally the 3990 can have a second 3390 string attached, giving a maximum of 64 devices in the subsystem.

Packaged in Hard Disk Assemblies with two actuator-head units and one set of platters, a model 1 HDA provides 1.89 GB before formatting and a model 2 provides 3.78 GB/HDA. The Model 3 enhancement to the drive family, announced September 11, 1991, increased capacity 1.5 times to 5.67 GB/HDA and the Model 9, announced May 20, 1993, further increased capacity 3 times to 11.3 GB/HDA.

All the preceding DASD models are equipped with a large AC motor, driving the HDA with a belt; however, the 3390 HDA is directly driven by a DC motor that is included in the enclosure.

The 3390 Model 9 was the last Single Large Expensive Disk (sometimes called SLEDs) drive announced by IBM.

IBM 9345
The IBM 9345 HDD first shipped in Nov 1990 as an RPQ on IBMs SCSE (SuperComputing Systems Extensions). Developed at IBM's San Jose, California laboratory under the code name Sawmill. It was an up to 1.5 GB full height 5$1/4$-inch HDD using up to 8 130 mm disks. It was the first HDD to use MR (Magneto Resistive) heads.

IBM 9340
In October 1991 the 9345 DASD was announced as part of the IBM 9340 channel-attached, count key data (CKD) DASD subsystem family which attached to IBM mainframes including the ES/9000 processor family. The 9345 DASD Model 1 had two 1.0 GB HDDs while the Model 2 had two 1.5 GB HDDs.

For most practical applications, the 9340/9345 was functionally equivalent to a 3990/3390, although without non-volatile RAM cache of the 3990 and with a somewhat shorter maximum block length than the 3390.

The OS's IOS component learned of this device's characteristics through a special initializer, IECCINIT, which also serviced other DASD device types, and for the same purpose. It was at initialization-time that the OS learned that the 9340 has no non-volatile cache and the 9345 has a shorter than expected track capacity. The initializer, therefore, assigned a different device type than the 3990/3390.

9330 family of disk drives

 * 1) 9331 Diskette Unit models 1 and 11 contained one 8-inch FDD while the models 2 and 12 contained one 5$1/4$-inch FDD.
 * 2) 9332 Direct Access Storage Device used the IBM 0667 HDD.
 * 3) 9333 High Performance Disk Drive Subsystem used the IBM 0664 or IBM 0681 HDDs depending upon subsystem model
 * 4) 9334 Disk Expansion Unit attaches from one to four SCSI HDDs to the RS/6000 system.
 * 5) 9335 Direct Access Storage Subsystem This HDD used in this subsystem was developed under the code name "Kestrel" at IBM Hursley, UK, and was an 850 MB HDD using three 14-inch disks with dual rotary actuators, each actuator accessing three surfaces with two heads per surface. The HDD was in the rack mountable 9335 announced as a part of the October 1986 IBM 9370 Information System announcement. There is no known OEM version of this HDD.
 * 6) 9336 Disk Unit used the IBM 0681 HDD (Redwing)
 * 7) 9337 Disk Array Subsystem used the IBM 0662 (Spitfire) or 0663 (Corsair) HDDs.

IBM 2310
The IBM 2310 Removable Cartridge Drive was announced in 1964 with the IBM 1800, and then in 1965 with the IBM 1130; it likely first shipped with the 1130 in late 1965. It could store 512,000 16-bit words (1,024,000 bytes) on an IBM 2315 cartridge. A single 14 in oxide-coated aluminum disk spun in a plastic shell with openings for the read/write arm and two heads.

IBM 5444
The IBM 5444 was announced September 1969 as part of System/3. Developed at IBM's Hursley, England, laboratory under code name Dolphin it used the 5440 disk cartridge. The cartridge in turn contained one 14-inch disk. There were three models:

 * Model 1 has one fixed disk and one removable disk each with 100 tracks per surface for a disk cartridge capacity of 1.23 MB
 * Model 2 has one fixed disk and one removable disk each with 200 tracks per surface for a disk cartridge capacity of 2.46 MB
 * Model 3 has only one removable disk with 200 tracks per surface for a disk cartridge capacity of 2.46 MB

IBM 62GV
The 62GV first shipped in May 1974. Developed at IBM's Hursley, UK, laboratory under the code name Gulliver with an initial capacity of 5 MB. Subsequent models have 10 MB (62TM) and 14 MB capacities. It used a Swinging Arm actuator with one 14-inch disk. The simple design of the actuator, invented at IBM's UK Hursley Labs, became IBM's most licensed electro-mechanical invention of all time, the actuator and filtration system being adopted in the 1980s eventually for all HDDs, and still universal nearly 40 years and 10 Billion arms later. During its production life the IBM 62GV shipped 177,000 units making it the first HDD known to have shipped in excess of 100,000 units.

OEM and Small Systems HDDs
This section lists IBM manufactured HDDs offered both as an OEM product and for attachment to IBMs small systems such as the System/3, System/32, /34 and /36 and the AS/400. HDDs are identified by their OEM model number and listed chronologically by date of first customer shipment.

IBM 0680
The 0680 first shipped in 1979 on most IBM small systems and the low end of the System/370 as the 3310 direct access storage. The OEM version was announced as the 0680 in September 1981. Developed at IBM's Hursley, UK, laboratory under the code name Piccolo with an initial capacity of up to 65MB, it used six 8-inch disks (210 mm) and had an improved rotary actuator.

A double capacity version, the 62SW, shipped in June 1984 but very few units were sold because its price per megabyte was the same as the 62GV.

IBM 0676
The 0676 first shipped in November 1982 as a 5247 Disk Storage Unit for the IBM System/23 Datamaster. Developed at the IBM Rochester, Minnesota, laboratory as the 21ED it was an 8-inch HDD with an initial capacity of 15 or 30 MB in two or foue 210 mm disks. In 1983 it shipped as the HDD in the 5360 System Unit of the S/36. In 1984 its capacity was doubled by doubling the number of tracks per surface and it was incorporated into the 5362 System Unit of the System/36.

IBM 0665
The 0665 first shipped in October 1985 in the system unit for the PC AT (5170). Developed under the code name "Pixie" at IBM Rochester, Minnesota, it was a 5$1/4$-inch HDD with capacities of 20, 30 and 44 MB.

IBM 0667
The 0667 first shipped in August 1986. Developed at IBM Rochester, Minnesota, under the code name "Grant", it was a 70 MB ESDI full height 5$1/4$-inch HDD with up to four 130 mm disks. It was offered as a feature on certain models of the PC RT (6150, 6151, 6152) and in System/36 Model System Units (5363, 5364).

IBM 0669
The 0669 first shipped in 1987. Developed at IBM Rochester, Minnesota, under the code name "Grant-Prime", it was a full-height 5$1/2$-inch HDD with a capacity of up to 115 MB on up to four 130 mm disks. It was the HDD internal to the System/36 5363 System Unit and Series 1 4956 System Unit.

IBM 0671
The 0671 first shipped in 1987. Developed under the code name "Lee" at IBM Rochester, Minnesota, it was an up to 316 MB ESDI full height 5$1/4$-inch HDD with up to eight 130 mm disks depending upon model. This was IBM's first usage of a thin metal film as the disk's recording surface. In 1988 it shipped as part of the 9404 System Unit of the IBM AS/400 system which contained two, or optionally three of these HDDs.

IBM 0661
The 0661 first shipped in 1989 as the model 371. Developed initially under the code name "Lightning" at IBM Rochester Minnesota (and IBM Hursley, UK) as a 320 MB SCSI HDD with up to eight 95 mm disks (14 heads), it was followed in 1990 with a 400 MB version, code named "Turbo". During 1990 it was added as a standard drive on several major IBM systems, e.g., IBM AS/400 System Unit Model CXX.

IBM 0681
The 0681 first shipped in April 1990. Developed at IBM's Hursley, UK, laboratory under the code name Redwing, it was the last HDD product developed at Hursley. It was an up to 857 MB full-height 5$1/4$-inch HDD using up to 12 130 mm disks. It was the first HDD to use PRML decoding of data. It was the drive component of the 9333 Disk Drive Subsystem which first shipped in early 1992.

A higher density, 1.07 GB, version was incorporated into the 9333 subsystem in May 1992.

IBM 0663
The 0663 first shipped in late 1991. Developed under the code name "Corsair", it was a 3$1/2$-inch HDD with the height of a 5$1/2$-inch half-height device (1.6-inch high) and up to 1 GB on up to 8 95 mm disks. It was offered as a feature on certain models of the PS/2 and RS/6000. It was the first OEM disk drive to use MR Heads.

IBM 0664
The 0664 first shipped in November 1992. Developed under the code name "Allicat" at IBM Rochester, Minnesota, it was a full-height 5$1/2$-inch HDD (3.25-inch high) that combined two 3$1/2$-inch devices in one, with up to 2.013 GB capacity on up to 8 95 mm disks.

IBM 0662
The 0662 first shipped in June 1993. Developed under the code name "Spitfire" at IBM Rochester, Minnesota, it was a full-height (1-inch high) 3$1/2$-inch HDD with 1.05 GB on three disks or five disk surfaces. It was the HDD internal to the 9336 Disk Unit and the 9337 Disk Array.

Floppy disk drive
Another important IBM innovation is the floppy disk drive. IBM first introduced the 8-inch FDD in 1971 as a read only program load device. In 1973 IBM shipped its first read/write floppy disk drive as a part of the 3740 Data Entry System. IBM established early standards in 8" FDDs but never sold such products separately so that the industry then developed separate from IBM.

IBM was at one point was the world's largest purchaser of OEM 5$1/4$-inch FDDs; its selection of the two-sided, 48 tracks-per-inch model helped establish the model as the de facto industry standard. IBM made extensive preparations to manufacture such models and smaller form factors but cancelled all such efforts in 1985. IBM's 1983 attempt to OEM its 4-inch DemiDisk failed.

"Star" series of HDDs
On October 17, 1994, IBM's Storage Systems division announced three new families of hard disk drives, the Travelstar 2$1/2$-inch family for notebooks, the Deskstar 3$1/2$-inch family for desktop applications and the Ultrastar 3$1/2$-inch family for high performance computer system applications.

IBM's first HDD versus its last HDDs
The following table compares IBM's first HDD, the RAMAC 350, with the last three models it manufactured in each of its "Star" series of OEM HDDs. It illustrates HDD's spectacular decline in cost and size along with corresponding improvement in capacity and performance.

DASD devices not HDDs or FDDs
IBM in some of its operating systems classifies HDDs and FDDs as DASDs, direct access storage devices. Other technologies so classified include:

IBM 7320 drum
The IBM 7320 is a magnetic-drum storage unit announced in 1962.

IBM 2301 drum
The IBM 2301 is a magnetic-drum storage device introduced in the late 1960s

IBM 2303 drum
The IBM 2303 is a magnetic-drum storage device introduced in 1964.

IBM 2321 Data Cell
The IBM 2321 Data Cell announced in 1964 is a device that uses short strips of magnetic tape to store data. It holds 10 40 MB removable cells, for a total capacity of 400 MB.

IBM 3850 Mass Storage System
The IBM 3850 Mass Storage System, announced in 1974, is a library system of tape cartridges that staged data from the cartridges onto physical IBM 3330 or 3350 disk drives which then appeared to the system as virtual 3330 drives.

title: History of IBM magnetic disk drives


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Alderley Edge

Alderley Edge is a village and civil parish in Cheshire, England. In 2011, it had a population of 4,780.

Alderley Edge is 6 mi northwest of Macclesfield and 12 mi south of Manchester, at the base of a steep and thickly wooded sandstone escarpment, Alderley Edge, which is the area's chief topographical feature and overlooks the Cheshire Plain.

Alderley Edge is known for its affluence and expensive houses, falling inside Cheshire's Golden Triangle. Alderley Edge has a selection of cafes and designer shops and has attracted numerous Premier League footballers, actors and multi-millionaire businesspeople. It is one of the most expensive and sought-after places to live in the UK outside London.

History

The area around Alderley Edge provides proof of occupation since the Mesolithic period with flint implements being found along the line of the sandstone outcrop. Evidence of copper mining in the Bronze Age has also been found to the south of the area. In 1995, members of the Derbyshire Caving Club found a hoard of 564 coins of the Roman Empire (now in the Manchester Museum) dating from AD 317 to AD 336. There are (to date) 13 recorded sites on the County Sites and Monuments Record (CSMR) in the settled area of Alderley Edge and 28 in Nether Alderley, with a further 44 along the Edge.

Early medieval settlements are recorded at Nether Alderley, to the south of Alderley Edge. The first written evidence of Alderley Edge, known then as Chorlegh (later spelt Chorley) appeared in the 13th century, the likely derivation being from ceorl and lēah, meaning a "peasants' clearing". Although not mentioned in the Domesday Book, it is included in a charter of c.1280. The name Alderley first appears in 1086 as Aldredelie. Several versions of the origin are known: one says it originated from Aldred and leah meaning "Aldred's clearing". Another says it is most likely that the name Alderley came from Old English language Alðrȳðelēah meaning "the meadow or woodland clearing of a woman called Alðrȳð".

In the 13th century and during the Middle Ages, the area comprised estates that had many owners. Since the 15th century, most of them have belonged to the De Trafford baronets. The principal manors were based on the 14th-century Chorley Old Hall, which is south-west of Alderley Edge, and the Old Hall, at Nether Alderley, a 16th-century building burnt down in 1779. The economies of Chorley and Nether Alderley were dominated by agriculture with a market charter granted at Nether Alderley in c.1253. Nether Alderley Mill dates back to 1391, although the present timber structure is 16th-century. The millpond was adapted to form the moat, which surrounded the Old Hall, the home of the Stanley family. The corn mill continued to be worked until 1939 when Edward Stanley, 6th Baron Stanley of Alderley, was compelled to sell it, along with the rest of the Alderley Park estate, to meet the cost of death duties. In the 1950s the National Trust bought the site and has since restored the building and opened it to the public.

Cheshire had its own system of taxes in the mediaeval period, the Mize; in the records for 1405, Chorley was assessed at 20s 0d and Nether Alderley at 27s 0d.

Lead and copper mining on the Edge is documented from the late 17th century to the 20th century. After the destruction of the Old Hall in the late 18th century, the Stanley family moved to Park House on the south edge of Alderley Park, and house and park were afterwards much extended. Throughout the 19th century Nether Alderley remained under the control of the Stanleys and the lack of development pressure meant that the dispersed medieval settlement pattern was retained. In 1830, Chorley consisted of only a few cottages, the De Trafford Arms Inn, a toll bar and a smithy; these were straggled along the Congleton to Manchester Road.

The coming of the railway in 1842, with the construction of the Stockport to Crewe section of the main Manchester and Birmingham Railway, changed all this. The Manchester and Birmingham Railway Company built the line through Chorley, offering free season tickets for 20 years to Manchester businessmen who built houses with a rateable value of more than £50 within a mile of the station. This 'season ticket' was in the form of a small silver oval which could be worn on a watch chain.

The railway also gave Alderley Edge its current name. As the railway network expanded and travel became easier, the railway company did not want its station called Chorley because of the possible confusion with Chorley in Lancashire. So, in 1880 they renamed it Alderley Edge railway station, against much opposition, taking the old name for the village and the name of the sandstone escarpment already known as The Edge. The name Chorley, Macclesfield is retained by the civil parish to the northwest of Alderley Edge.

Following the construction of the railway, the local landowner, Sir Humphrey de Trafford, of Chorley Hall, laid out an extensive estate of new roads and new houses were incrementally added, filling in most of the available sites by 1910. Of these, nine are now listed grade II. The area boundary largely reflects de Trafford's original estate boundaries. Also because of the railway, Alderley became a popular place to visit and the railway company popularised day trips and cheap excursions to the village.

This period also saw the appearance of buildings which are now landmarks. St Philip's Church, Alderley Edge, with its 175 ft spire, was built in 1853 and the village primary school a year later known as Alderley Edge Community Primary School. Two all-girls schools were opened, St Hilary's in 1876 and Mount Carmel in 1945, which then merged in 1999 to form Alderley Edge School for Girls. A boys' school, The Ryleys School, was opened in 1877. The Mission Hall (later known as The Institute) was built as a temperance hall for the recreation of the 'lower classes' by the wealthier residents in 1878. The Methodist Church in Chapel Road was built ten years after St Philip's.

The area is notable for its heavily wooded streets and substantial Victorian villas set in spacious gardens. The first villa was constructed in the early 1840s and by 1850 thirty "handsome residences" had been erected, some of them in what is now the Alderley Edge Conservation Area. Cotton barons from Manchester built their mansions here and now (as at around 2010) they are changing hands for several million pounds. The village winds up a high street with many restaurants, designer shops and speciality food shops. Around the village, winding lanes are covered in their original sandstone setts and front boundary walls are usually built from the same local sandstone. The buildings are varied in style with examples of mock Tudor, Italian, neo-Georgian and Arts and Crafts Movement designs. The wide range of materials used reflects this somewhat eclectic mix of styles, and includes stone, brick (several colours), smooth render or roughcast for the walls, and Welsh slate or clay tiles for the roofs.

The growth of Alderley Edge is recorded in the census returns, with the population rising from 561 in 1841 to 2,856 in 1902 (the return for Nether Alderley shows a drop from 679 to 522 within the same period). There was no church in Chorley until 1852, when the larger expansion of the town in the demanded enlarged accommodation, but St Mary's Church retains some 14th-century work including a font.

The First Edition Ordnance Survey map of 1871 therefore shows Chorley (as it still was), with the new Queen's Hotel next to the station, new shops and terraced houses along London Road, and a Post Office at the town centre, where Macclesfield Road meets Alderley Road. To the north are wooded areas with detached villas, but to the east is a much larger area, roughly approximating to the modern conservation area, where curving roads divide generous wooded plots, usually with its own house, although some plots remained undeveloped until much later. Of interest is the use of the names Brickfield and Brick kiln on a site to the north-east of Alderley Edge, suggesting a source for the local bricks.

The 1899 map shows a similar footprint but it is much easier to make out the individual villas and their names, such as Holybank, Ashfield (Alderley Edge villa) and The Larches. Also very evident on this map are the remains of the old mines towards and within Windmill Wood, immediately to the south-east.

In the 20th century, Alderley Edge continued to expand with much post-war housing around the north-eastern and western edges. Nether Alderley has remained relatively unchanged, apart from the sale of Alderley Park to Astra Zeneca (previously ICI, Imperial Chemical Industries). Astra Zeneca has since sold Alderley Park to Manchester-based, family-owned property company Bruntwood. The park is now home to 150 science companies and is the UK's largest single-site life-science facility, along with commercial workspace, residential and retail spaces.

Administrative history
From medieval times the area was part of the Chorley township of the ancient parish of Wilmslow in the Macclesfield Hundred of Cheshire. Under the Poor Law Amendment Act 1866 Chorley became a civil parish in its own right. Alderley Edge civil parish was created on 31 December 1894 from part of Chorley civil parish. Along with Bollinfee civil parish it formed Alderley Edge Urban District. In 1974 it became a civil parish in the new non-metropolitan district of Macclesfield. Since 1 April 2009 it has been part of the unitary authority of Cheshire East.

Boundary changes
The civil parish was enlarged on 30 September by gaining a further part of Chorley. On 1 October 1910 it was enlarged by gaining part of Nether Alderley civil parish. It was further enlarged on 1 April 1936 by the transfer of a further 2 acre from Chorley and 19 acre from Wilmslow civil parish and by gaining 112 acre on the abolition of Bollinfee civil parish.

Economy
At the 2001 UK census, the ward had a possible workforce of approximately 2,157 people. The economic activity of residents in the Alderley Edge electoral ward was 36.9% in full-time employment, 10.2% in part-time employment, 29.3% self-employed, 1.7% unemployed, 1.4% students with jobs, 3.5% students without jobs, 19.3% retired, 7.5% looking after home or family, 2.8% permanently sick or disabled and 2.0% economically inactive for other reasons.

Alderley Edge has a very high rate of self-employment (29.3%) compared with rest of the Macclesfield borough (22.7%) and England (16.6%). It also has low rates of unemployment (1.7%) compared with the rest of the Macclesfield borough (2.0%) and England (3.3%). The Office for National Statistics estimated that, during the period of April 2001 to March 2002, the average gross weekly income of households in Alderley Edge was £720 (£37,440 per year).

The Edge
The Edge is a wide red sandstone escarpment situated above the village of Alderley. An edge is used as a descriptive term for high land in Cheshire and adjacent counties, such as in Wenlock Edge and Blackstone Edge. The Edge at Alderley is a ridge of land separating a narrow and short valley from the higher ground of southeast Cheshire and Derbyshire. It rises gradually from the town of Macclesfield, until, at a distance of 7 or 8 kilometres, it terminates abruptly, having reached a height of nearly 215 metres above sea level, and 110 metres above the Cheshire Plain below it.

It was formed partly by the weathering of resistant sandstone lying on top of a softer sandstone, and partly by faulting of the rocks. The scarp or slope is repeated eight times by faults of up to 200 metres, which has thrown down blocks of sandstone west to Alderley and east to the village of Kirkleyditch. The northern side of the Edge is shaped like a horse shoe or hough (pronounced huff), as this type of ridge is called in Cheshire. The Edge also marks the line of a hamlet of scattered houses called The Hough, which descend towards Alderley village.

The Edge is owned by the National Trust. It is maintained as a public access wooded area and is a popular destination for day trippers from Manchester and the nearby towns of Wilmslow and Macclesfield, attracting 300,000 visitors a year. There is a car park with toilet facilities. The Edge has been designated a Site of Special Scientific Interest for its unique geology. Its woodland area is riddled with the old Alderley Edge Mines.

Views
From its highest point, the Edge affords panoramic views across Cheshire and the Peak District and walking paths through the property, as well as one to nearby National Trust property Hare Hill. From the Edge, the Cheshire Plain, can be seen extending from the area of Macclesfield Forest on the south east side with its undulating land and woods, towards the extreme easterly point of the Derbyshire peaks, and northerly to Manchester and Blackstone Edge in Yorkshire.

Until trees were planted at the Edge (1745–1755), visitors to the Edge could see a full 360° panorama of the country around; today the view from the Edge itself is limited to the northerly and easterly directions. Trees now obscure the views in other directions, including views of the Wrekin in Shropshire to the south; The Cloud near Bosley and Mow Cop (where the Cheshire Plain meets the Peckforton Hills, Beeston Castle, and the Delamere Forest) to the southwest; and west to the mountains of North Wales.

History
The Edge was described as a dreary common till the year 1779, when it was enclosed together with all the other waste lands of Alderley. Some hundreds of Scots pines were planted on the highest points by Sir James and Sir Edward Stanley, between 1745 and 1755; before that time, it does not appear that a single tree grew on it.

In 1882, George Ormerod in his book The History of Cheshire described the Edge as "an abrupt and elevated ridge, formerly the site of a Beacon, which bears the appearance of having been detached by some great convulsion of nature from the range of the Macclesfield hills, as Helsby and Beeston seem to have been from those of Delamere and Peckforton. Near the summit, "cobalt ore, lead, and copper have been got in small quantities. The sides are varied with cultivated land, wood, and rock; and the entire mass presents a striking object to all the surrounding district, over which it commands a most extensive prospect."

Alderley Edge mines
The escarpment in Alderley Edge has long been a site of copper mining. Archaeological evidence indicates that mining took place here during Roman times and the Bronze Age, and written records show that mining continued here from the 1690s up to the 1920s. Many of the mines are owned by the National Trust and have been leased from them by the Derbyshire Caving Club which maintains access and continues to explore and search for areas of mining that have been closed for centuries.

From the 1860s onwards, there have been many thousands of visitors to the mines. However, many other visitors, especially between 1940 and 1960, were ill-equipped and unprepared; this led to a series of accidents that gained the mines a notoriety which still haunts them today. The West and Wood Mines were finally blocked in the early 1960s (Jones, 1961). In 1969, the Derbyshire Caving Club obtained permission from the National Trust (the owners) to reopen Wood Mine and since then much has been found by excavation and exploration and thousands of people have visited the mines in supervised groups.

Historic buildings

There are many historic buildings including Chorley Old Hall, which is the oldest surviving manor house in Cheshire.

To the south of the village is the Alderley Park estate, former ancestral home of the Stanleys.

Local legends
There are several local legends, the most famous being that of the Wizard of the Edge.

The Wizard of the Edge
Legend has it that a farmer from Mobberley was taking a milk white mare to sell at the market in Macclesfield. Walking along the Edge, he reached a spot known locally as "Thieves Hole" where an old man clad in a grey and flowing garment stopped him. The old man offered the farmer a sum of money for his horse but the farmer refused, saying he could get a better price at the market. The old man told the farmer that he would be at this spot again that evening when the farmer returned, not having found a purchaser for the horse. So the farmer went to market; but having failed to sell the horse, returned in the evening and made his journey back along the Edge. At the same point, the old man appeared again, repeating his offer, which this time was accepted. The old man told the farmer to follow him with the horse. As they approached an area just past Stormy Point, the old man held out a wand and uttered a spell, opening the rock revealing a pair of huge iron gates, which the wizard – as he was – opened. Assuring no harm the wizard told the farmer to enter. The farmer did so, and was led through the gates into a large cavern. In the cavern, the farmer saw countless men and white horses, all asleep. In a recess there was a chest, from which the wizard took the payment for the horse, which he gave to the farmer. The astonished farmer asked what all this meant; the wizard explained that all these sleeping warriors were ready to awake and fight should England fall into danger. He then ordered the farmer to leave and return home.

There are several versions of the legend. It first appeared in print when a letter, sent by someone using the pseudonym "A Perambulator", was published in the Manchester Mail in 1805. "A Perambulator" wrote in his letter that the story had been related to him by an old servant of the Stanley family of Alderley, and it used to be told by Parson Shrigley, former Clerk and Curate of Alderley (who was in the post from 1753 until his death in 1776 and is buried in Alderley Church). It subsequently appeared in expanded form in a tourist pamphlet, in both prose and verse forms, the former under the title The Cheshire Enchanter and the latter The Legend of the Iron Gates. Several versions include parts of prophecies made by Robert Nixon in the wizard's explanation to the farmer, such as "There will come a day when these men and these horses, awakening from their enchanted slumber, will descend into the plain, decide the fate of a great battle, and save their country. This shall be when George the son of George shall reign." Some later variations, such as a poem by James Roscoe, say that the Wizard was Merlin and the sleeping men were King Arthur and his army.

Similar legends
There are a number of similar British legends which closely resemble the Alderley one, though since they are all founded in oral tradition it is not possible to know which came first. In one, set in the Eildon Hills in Scotland and narrated by Sir Walter Scott, the old man is named as Thomas of Erceldoune and the horses are black. Once in the cave, the old man asks the farmer to choose between a sword and a horn. The farmer chooses the horn, and immediately the horses all jump up and start to stamp their hooves on the ground. The terrified farmer is expelled from the cave by a whirlwind and hears the words "Woe is the coward that ever was born, that did not draw the sword but blew the horn". Another very similar one was made into a ballad called Sir Guy the Seeker by Matthew 'Monk' Lewis, and is based on a legend of Dunstanburgh Castle. In his preface to Sir Guy the Seeker Lewis pointed out the similarity to the Alderley legend.

Alan Garner used the legend of The Wizard of the Edge, and other local legends, in his novels The Weirdstone of Brisingamen and The Moon of Gomrath. Garner, born in Congleton, was raised in Alderley Edge.

Gold and coins
Several ancient gold bars have been found at Alderley Edge, the first on Artists Lane. It was declared treasure trove, and an inquest was held in Congleton on 26 February 1993. John Cherry from the British Museum along with Adrian Tindall, the Principal Conservation Officer (Archaeology) for Cheshire County Council, reported that the gold bar weighed 97.01 grams and was determined to be 73% gold. The publicity caused the public to search for more, and indeed five more gold bars were found.

Members of the Derbyshire Caving Club found a Roman coin hoard in 1995; the hoard contained 564 coins from AD 317–36.

Roads
After several decades of discussion, a 5 km, north-to-south A34 Alderley Edge bypass was constructed (officially named Melrose Way ) to the west of Alderley Edge to reduce traffic flow through the centre of village. It starts at the Harden roundabout at the south end of the existing Wilmslow bypass and goes west of Alderley Edge and rejoins the A34 at the bend about 400 yards north of the south gate of Astra Zeneca's laboratory grounds.

The bypass was constructed to relieve the congestion caused by the 26,000 vehicles that previously passed through Alderley Edge daily. The project cost £56 million and the main civil engineering works were contracted to Birse Civils. The bypass was officially opened by the Chancellor of the Exchequer and MP for Alderley Edge, George Osborne, on Friday 19 November 2010, "over 6 months before schedule" according to a notice that contractors put up at its south end.

Railway
Alderley Edge railway station is situated on the Crewe to Manchester line, which is a spur of the West Coast Main Line. There are generally two trains per hour to Crewe, two to Manchester Piccadilly via Stockport and one to Manchester Piccadilly via Manchester Airport; on Sundays, there is an hourly service each way between Crewe and Manchester Piccadilly, via Stockport.

The station is managed by Northern, who also operate all services that stop here.

Buses
Alderley Edge is served by the 130 bus route, which is operated by D&G Bus; it runs hourly during the daytime (except Sundays) between Macclesfield, Wilmslow and Manchester Airport.

In popular culture
Alderley Edge has been used as a major setting in various books and television shows:
 * It was the main setting of the Channel 4 show Goldplated
 * The location inspired Peter Graham to compose "On Alderley Edge", a commission for the Black Dyke Band.
 * It was the main setting of the MTV show Living on the Edge
 * The Edge and the country south of it was the setting for Alan Garner's novels The Weirdstone of Brisingamen and The Moon of Gomrath.
 * The village has been featured in the ITVBe show The Real Housewives of Cheshire.

Notable residents
After the death of their father in 1870, George Gissing and his two younger brothers were sent to Lindow Grove, a Quaker boarding school in Alderley Edge, whose headmaster James Wood was often parodied by the novelist.

The Pilkington family (of Pilkington's Glass) owned all of the woodland now known as The Edge until 1948, when their daughters donated the land to the National Trust. The Pilkington company developed the toughened safety glass necessary when motor cars and very tall buildings became popular. They became hugely wealthy. On Woodbrook Road they built The Cedars as the family home, which has a distinctive large tower and is built from white stone. The house is now sub-divided into four luxury dwellings.

The author Alan Garner, who wrote the children's fantasy novel The Weirdstone of Brisingamen, which is set on Alderley Edge, lived on Trafford Road at the corner with Stevens Street and Moss Lane.

Former footballers who live in Alderley Edge include Joleon Lescott and Manchester United players Dwight Yorke, Rio Ferdinand, Michael Carrick, and Andy Cole. David Beckham and his wife Victoria Beckham previously resided in Alderley Edge. A number of Coronation Street actors, including Helen Flanagan and Richard Fleeshman, live in the village, as do musicians Bernard Sumner and Peter Hook.

The singer-songwriter Matty Healy spent his formative years in Alderley Edge together with actor parents Denise Welch and Tim Healy.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Alderley Edge


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Talk:Geodesic flow

I do not see a reason to redirected to Exponential map

title: Talk:Geodesic flow


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Talk:What's My Line?

Editing to condense
I did a lot of editing to condense this article. In many places the writing style seemed excessively wordy, with trivial needless detail, repetitive facts, etc. I'm hoping I didn't step on too many toes as I tried to retain content. I did the editing in short stages so I could explain each change. Also I notice that there is language here that's very informal.

I also think the section "Syndicated revival (1968–1975)" is far too long. The status of WML comes primarly from the original run and not the later syndicated version. It may have had a decent run, but it doesn't deserve anywhere near this much detail. It deserves a couple paragraphs and certainly not details about set design and who designed it!! Even the section on "New Versions of WML" was long. I removed details about how To Tell the Truth has continued on, because why is that relevant to WML even if it is the "sister" show? BashBrannigan (talk) 02:14, 4 May 2009 (UTC)
 * I think you've done a good job in condensing. At one time, a lot of content was added in a less than encyclopedic manner and while some editing of it has been done, there still remained too much fluff. This is a move in the right direction. Wildhartlivie (talk) 02:34, 4 May 2009 (UTC)

I wouldn't say that the section on the syndicated version of the show was "far too long". For one thing, a lot of people like me -- I'm 62 now -- saw the syndicated version more than the original. Further, the syndicated version was on five nights a week (Monday through Friday). There were 876 episodes broadcast by the CBS network from 1950-1967. From 1968-1975, however, the syndicated version of "WML?" broadcast 1,315 episodes, more than the original show. The fact is, a lot of us were too young to stay up until 10:30 p.m. on Sundays to see the original show, but the syndicated show was on around 7:30 p.m. in many markets, to fill in the gap between the nightly news shows and prime-time TV, and we were adults by then and could watch it. Toddabearsf (talk) 19:41, 15 November 2014 (UTC)
 * For what it's worth, the comments you are responding to are over five years old. I don't think disagrees with you that the syndicated show is worth documenting. The size of the section on the syndicated version has been consistent now for a long time. In 2009 editor BashBrannigan was doing excellent work in removing redundant and irrelevant material from the article and addiing well-sourced information, working to bring it around to the much better article seen today. I don't think anyone in 2014 wants to shorten the syndicated section, although it would benefit from more carefully researched and documented writing. Cheers,Markhh (talk) 21:34, 15 November 2014 (UTC)

Improving Style
I thought I should clarify recent edits. If anyone feels I've done wrong on anything, please let me know. Too much of the style seems to be a succession of point-form and excess detail. I’m not much of a writer, but I’ve tried to keep the content but make it more integrated instead of point-form. With the excess detail, too much detail is needless and boring and should stay in the source material. For example, if specific dates are given, then it should be in the case of significant dates; when the show began or ended, but not when it switched from Wednesdays to Thursdays. Or, is it important that Ernie Kovaks was on the show for 9 episodes? If we’re going to include that, then there is a lot more far more interesting detail that could be added. BashBrannigan (talk) 19:59, 1 July 2009 (UTC)

I thought I should make special comment on my last two edits on the Standard, Mystery rounds and the Syndicated version. It would appear there were massive changes, however it was just a re-organization. With minor exceptions, all content has been retained. BashBrannigan (talk) 18:22, 4 July 2009 (UTC)

I've removed the issues dealing with tone/style. I've worked on improving the style of the article, to make it more encyclopedic and believe this issue has been mostly resolved. However, if anyone feels there are still problems in this area, please express specifically where improvements can be made. If memory serves it was Wildhartlivie who added that Article Issues so their input would be welcome.

It seems to me the problems with the article made still be length and some content. I do believe the section on the syndicated version is too long, but I'm uncertain as to how to shorten it.BashBrannigan (talk) 02:11, 14 July 2009 (UTC)

I made another major reorganization, but it is likely the last. I think it makes the article easier to read. The sections "US Versions" and "See Also" appeared to be "artificial". The material in both should be worked into the main article. This is what I did with the Radio Version info. It was also apparent that a new section could be created for WML post-1975. I moved 25th Anniversary special, Live Stage version, "Episode Status" and "That's My Line" into here (from the "See Also"). The only serious deletion was the "Front Page Challenge" reference in See Also. I was a huge fan of FPC but i can't see it's relevant to WML. I would welcome comments about this reorganization. BashBrannigan (talk) 02:01, 19 July 2009 (UTC)

 * You've made some marvelous improvements to this article, and although I haven't posted here about them, I've been watching as often as I could. I made some very minor style changes, mostly correcting punctuation placement (which needs to come before references), some italics, etc., but no content edits. I removed a couple of tags that were placed a long time ago by someone else. While a good article nomination might bring issue with the YouTube cites, unless you're thinking of that, I think they're helpful for anyone who wants to see them and don't take issue with them here now. I'd also note that there is a template for individual broadcast references if one were inclined to use them, but they aren't required. I removed a few cite tag qualifiers (asking for page numbers) that are probably not necessary now, they were placed for entirely different reasons due to an editor who worked on the page who is now blocked. It wasn't always clear what was actually in the cites that were placed at the time. I've also removed the header tags since the article doesn't run too long and a great many cites have been added. The remaining inline citation tags are fine for what's left. If you happen to have citation information about any of the books used for citations, those would be great to add to a Further reading section or just a Works referenced section in the References section. You've done some great work here, Bash. Congratulations! Wildhartlivie (talk) 03:05, 19 July 2009 (UTC)

longest-running game show in the history
I've modified this restrict the claim to the US. The linked source only makes this claim about the US. There seems to be some evidence that it there are other longer running game shows in other parts of the world. I am not sure how the claim relates to other US game shows such as Wheel of Fortune, since What's my line was a syndicated show for 8 of 26year run. 60.240.207.146 (talk) 00:41, 10 October 2010 (UTC)

More on Citations
Why is there a tag on this article, when there are at least 53 references? Let us review the policy that Wikipedia sets forth for inline citation requirements. You do not have to place inline citations for each and every statement ever made in anyone's life. The only time it is required (which is opposite from what many believe it to be) are: ''1. Direct quotations. 2. Any challenged statement. 3. Any statement likely to be challenged. 4. Contentious material''. That's it! In addition to which, Wikipedia specifically states, "Wikipedia does not have a 'one inline citation per sentence' or 'one citation per paragraph' rule, even for featured articles. Wikipedia requires inline citations based on the content..." I don't know what has happened, but too many out there have forgotten these rules and expect every single sentence to be sourced, which is absolutely incorrect. Here's the thing: The tag needs to be removed and anything that qualifies for a citation should be tagged instead. It is entirely unhelpful to tag the entire article saying more sources are needed when in fact what it may need are specific sources and no one can read your mind! For this reason, I'm removing the tag. Please feel free to tag statements that require citations instead. MagnoliaSouth (talk) 18:21, 25 June 2014 (UTC)

 * You make some very good points (though maybe a little overly emotional). Thanks for posting. --Musdan77 (talk) 23:08, 26 June 2014 (UTC)

CBS Studio Locations
" The show was produced at CBS Studio 52 and, towards the end of its run,[specify] at CBS' Studio 50 (now the Ed Sullivan Theater) in Manhattan."

I'm not sure where the show was originally produced, but it didn't move to CBS Studio 52 until 1960. The first show broadcast from Studio 52 was on June 12, 1960, over ten years since the show premiered on February 2, 1950. It had to have been produced somewhere for the first 10+ years. After Studio 50, a.k.a. the Ed Sullivan Theater, was upgraded for broadcasting in color, several shows moved there, including "What's My Line?". The first broadcast in color of "WML?" was on September 11, 1966, and I'm reasonably sure that was also the first from Studio 50, especially since that date was not quite a year before the final episode on CBS was aired. Toddabearsf (talk) 19:35, 15 November 2014 (UTC)

Syndicated episode count
There were actually 1,320 episodes. http://web.archive.org/web/20051104000155/http://www.matchgame.org/episodeguides/wml/wml7.html97.90.20.29 (talk) 00:11, 12 January 2015 (UTC)

External links modified
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 * Not working unfortunately. Says can't play because youtube account was terminated. Same for the original. Guess it doesn't work with youtube links? 8bitW (talk) 15:43, 9 February 2016 (UTC)

International versions
Would we be better off replacing the "international versions" section with a table, as at the article for the similar show To Tell the Truth? As it is now, the section seems a bit unwieldy. Moreover, it presumably be of most interest to readers of Wikipedia in other languages, who can get to their respective articles via the links on the left-hand side. What do you think? 8bitW (talk) 01:43, 9 February 2016 (UTC)

External links modified
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International versions
Are some international versions, with the British version an obvious contender, notable enough that they should be split into their own articles? Dunarc (talk) 20:14, 26 December 2017 (UTC)

What does this mean?
"Each panelist took those occupation cards gave each to the appropriate contestant (the ones who they thought had that occupation). " I've read this sentence several times and understand neither the semantics nor the syntax. Kdammers (talk) 07:50, 17 May 2018 (UTC)

CBS Acquisition
The article omits the acquisition of What's My Line? by CBS from Goodson Todman in the 1960's. CBS owned the show but Goodson Todman continued to act as producers under contract. This is reflected in the credits as "a CBS Television Network production in association with Mark Goodson and Bill Todman" replacing the former "Mark Goodson - Bill Todman production". — Preceding unsigned comment added by 172.91.176.10 (talk) 21:40, 17 October 2021 (UTC)

The Most Amusing Mystery Guest
Surprisingly, by far the most amusing mystery guest segment was the appearance of Salvador Dali, which was so funny that it has to be seen to be believed. I don't want to offer any spoilers but for almost every question, he could honestly answer "yes" because he was involved in so many different aspects of the arts. After a while, it became bizarre to behold for the studio audience as well as Daly and the panel. For example, when asked late in his appearance if he were a writer, he answered affirmatively to the audience's and Daly's surprise, visibly counting off the books he'd written during their quick whispered conference, then when Bennett Cerf asked if his company Random House had published any of the mystery guest's books and Dali answered "yes," pandemonium ensued. I'm trying to think of a way of obliquely steering our readers to that episode in the article since it's so noteworthily entertaining but haven't managed to do so. Racing Forward (talk) 20:27, 9 June 2022 (UTC)

title: Talk:What's My Line?


text:
Calcasieu River

The Calcasieu River (Rivière Calcasieu) is a river on the Gulf Coast in southwestern Louisiana. Approximately 200 mi long, it drains a largely rural area of forests and bayou country, meandering southward to the Gulf of Mexico. The name "Calcasieu" comes (via French) from the Indian Atakapa language katkosh, for "eagle", and yok, "to cry".

Course
The Calcasieu rises in Vernon Parish, north of Leesville, and flows initially southeast, passing through the Kisatchie National Forest southwest of Alexandria. It then turns southwest, flowing past Oakdale and Lake Charles, the largest city on the river. It enters the north end of the brackish Calcasieu Lake, an estuary on the Gulf of Mexico approximately 10 mi southwest of Lake Charles. The lake, which is referred to by locals as "Big Lake", is connected by a 5 mi channel to the gulf on the south end. The lower portion of the river south of Lake Charles is paralleled by a navigable canal which connects to the Gulf Intracoastal Waterway.

History
In the early 19th century, the area of present-day Louisiana and Texas west of the Calcasieu River extending roughly north-south to the Arroyo Hondo in Natchitoches Parish and east of the Sabine River was disputed between the United States and Spain. The dispute arose from differing interpretations of the western boundary of Louisiana under the terms of the Louisiana Purchase. The area became known as Neutral Ground and became a haven for privateers outside the legal jurisdiction of both nations.

During the US Civil War, a naval engagement occurred on May 6, 1864 at Calcasieu Pass, with the Confederates capturing two Union gun boats.

Water quality
Because the river passes through areas with intensive petroleum refining and other industries, petrochemical wastes have been found contaminating the river and estuarine environment along the lower Calcasieu River. A 1993, a Condea Vista Chemical Company pipeline spill was reported by the company to have leaked 1,600,000 lb of a highly toxic chemical known as ethylene dichloride. Mother Jones reported the spill as potentially discharging between 19000000 and 47000000 lb, that would have spread throughout parts of the estuary.

Sasol Ltd purchased Condea Vista in 2000 inheriting the controversy. The site was designated a "super-fund site" and Sasol has been involved in long-term legal battles that have resulted in settlements, fines, and the clean-up of affected areas. A problem is that the chemical sinks in water and becomes covered by deposits of silt. Any clean-up would inevitably stir up the covered chemical, causing further ecological damage. The lower end of the estimated spill (19,000,000 lb) would be two times the 1988 US production of ethylene dichloride, which was 9,445,000 tons. 1.6 million tons were cleaned up. Any construction might disturb contaminated soil so would have to be constantly monitored.

title: Calcasieu River


text:
User:Chaipau

I am Chaipau, the chai guy. Chaipau is the protagonist in the movie Salaam Bombay. I was an admin on Assamese Wikipedia, but now I am not.

Some Important Material

 * User:Sitush/CasteSources
 * Reliable_sources/Noticeboard/Archive_172
 * Alphabet vs script in Wikipedia. This comes up once in a while.

title: User:Chaipau