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 words (1,024,000 bytes) on an IBM 2315 cartridge. A single 14-inch (360 mm) oxide-coated aluminum disk spun in a plastic shell with openings for the read/write arm and two heads.

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IBM 2314/2319

The IBM 2314 Disk Access Storage Facility was introduced on April 22, 1965, one year later after the System/360 introduction. It was used with the System/360 and the System/370 lines. With 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-inch (360 mm) 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 had 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 consisted of the 2314 control unit, a 2312 single drive module, and two 2313 four drive modules for a total of 9 disk drives. Only eight drives of the nine were available to the user at any one time. The ninth drive was there for a spare for the user and could also be worked on 'offline' by a Field Engineer while the other drives were in use by the customer. Each of the nine drives were mounted in individual drawers that were unlatched and pulled out to access the Disk Pack. Because of their appearance they picked up the nickname of 'Pizza Ovens'
Other 2314 Models came later: 2314 Model A with combinations of one to nine drives. 2314 Model B with 2319 disk drives were available in three, six and nine drive models. A 2844 Control Unit could be added to the 2314 Control Unit which allowed two S/360 Channels simultaneous access to two separate disk drives in the Storage Facility.

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IBM 2311

The IBM 2311 Direct Access Storage Facility was introduced in 1964 for use throughout the System/360 series. It was also available on the IBM 1130 and (using the 2841 Control Unit) the IBM 1800. The 2311 mechanism was largely identical to the 1311, but recording improvements allowed higher data density. The 2311 stored 7.25 megabytes on a single removable IBM 1316 disk pack (the same type used on the IBM 1311) consisting of six platters that rotated as a single unit. Each recording surface had 200 tracks plus 3 optional tracks which could be used as alternatives in case faulty tracks were discovered. Average seek time was 85 ms. Data transfer rate was 156 kB/s.
The 2311 had 10 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. The 2311 was organized into cylinders, tracks, and records. (A cylinder referred to all surfaces the same track on each of the 5 platters.) Record 0 was reserved for timing.
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.

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IBM 2305

The IBM 2305 Direct Access Storage Facility was a fixed-head disk drive originally announced in 1970 to connect to the 360/85 and 360/195 using the IBM 2880 Block Multiplexor Channel. The 2305-1 ran at 3.0 MB/second when attached using the 2-byte channel interface, and the larger 2305-2 ran at 1.5 MB/second.
The 2305/2835 Storage Facility became popular with the System/370, and used as the paging device of choice, for systems 155-2, 158, 165-2 and 168. This was particularly true at IBM internal data centers where obsolete equipment was often all that was available. When floor space was not at a premium, the fixed head storage devices gave paging performance comparable to the alternative of using only the small amount of disk space located under one seek position of a standard disk drive and leaving the rest of the volume empty, which was a common practice in high transaction environments such as airline reservation systems, for paging and high volatility data storage.

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