The basic mechanical arrangement of hard disk drives hasn't changed since the IBM 1301. Disk drive performance and characteristics are measured by the same standards now as they were in the 1950s.
The IBM 350 was part of the IBM RAMAC 305, the computer that introduced disk storage technology to the world. IBM introduced the IBM 350 storage unit on September 4, 1956 before unveiling the entire RAMAC 305 computer nine days later on September 13. RAMAC stood for "Random Access Method of Accounting and Control."
Its design was motivated by the need for real time accounting in business. The 350 stored 5 million 7-bit (6-bits plus 1 odd parity bit) characters (about 4.4 megabytes). It had fifty diameter disks with 100 recording surfaces. Each surface had 100 tracks. The disks spun at 1200 RPM. Data transfer rate was 8,800 characters per second. Two independent access arms moved up and down to select a disk and in and out to select a recording track, all under servo control. A third arm was added as an option. 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 The 350 was officially withdrawn in 1969.
The 350's cabinet was 60 inches (approx. 1.52 meters) long, 68 inches (approx. 1.72 meters) high and 29 inches (approx. 74 centimeters) deep. IBM had a strict rule that all its products must pass through a standard 29.5 inch (approx. 75 centimeters) doorway. Since the 350's platters were mounted horizontally, this rule presumably dictated the maximum diameter of the disks.
A major advance over the IBM 350 and IBM 1405 was 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 eliminated 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 was also faster since, with the new design, the head would usually be somewhere in the middle of the disk, not starting on the outer edge. Maximum access time was reduced to 180 milliseconds.
The 1301 also featured heads that were aerodynamically designed to fly over the surface of the disk on a thin layer of air. This allowed them to be much closer to the recording surface, which greatly improved performance.
The 1301 was connected to the computer via the IBM 7631 File Control. Different models of the 7631 allowed the 1301 to be used with a 1410 or 7000 series computer or shared between a 7000 and a 1410 or between two 7000's.
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.
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 was about the size and shape of a top-loading washing machine and stored 2 million characters on a removable IBM 1316 disk pack. Each disk pack was high, weighed 10 pounds (4.5 kg) and contained six diameter disks, yielding 10 recording surfaces (the outer surfaces were not used). The 10 individual R/W heads were 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 disks spun at 1500 rpm. Each recording surface had 100 tracks with 20 sectors per track. Each sector stored 100 characters. Seven models of the 1311 were introduced during the 1960s. They were withdrawn during the early 1970s.
Models of the 1311 disk drive
The optional special features were
Drive 1 (the master drive: models 1, 3, 4, and 5) was about a foot wider than the other drives (the slave drives: model 2), to contain extra power supplies and the control logic.
The IBM 1316 Disk Packs were covered with a clear plastic shell and a bottom cover when not in use. A lifting handle in the top center of the cover was rotated to release the bottom cover. Then the top of the 1311 drive was opened and the plastic shell was lowered into the disk drive opening (assuming it was empty). The handle was turned again to lock the disks in place and release the plastic shell, which was then removed and the drive cover closed. The process was reversed to remove a disk pack.
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. The 2311 mechanism was largely identical to the 1311, but recording improvements allowed higher data density. The 2311 stored 7.25 million bytes 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.
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.
IBM operating systems address rotating direct access storage devices with a 5-byte CCHHR address. The CCHHR refers to the addressed Cylinder, Head, and Record numbers. With the introduction of the 2321 this format was extended to the 8-byte MBBCCHHR format. The M field is the 2321 Module number and the BB field is the 2321 Bin number.
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. Its removable disk packs held 100 MB (404x19x13,030 bytes) (the 1973 Model 11 featured IBM 3336 Disk Packs that held 200 MB (808x19x13,030 bytes)). Access time was 30 ms and data transferred at 806 kB/s. A major advance introduced with3330 was the use of error correction, which made the drives more reliable and reduced costs because small imperfections in the disk surface could be tolerated. The circuitry could correct error bursts up to 11 bits long. The 3330 was withdrawn in 1983.
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.
The significance of this product, and the reason that disk drives in general became known as "Winchester technology" had nothing to do with the configuration of the product. This was IBM's first drive to not unload the heads from the media. The 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 rapidly became a standard design within the disk manufacturing community.
The IBM 3380 Direct Access Storage Device was introduced in June 1980. It used new film head technology and had a capacity of 2.52 gigabytes 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 problems encountered, the first units did not ship until October, 1981.
IBM's "first" floppies were in diameter and held 80 Kilobytes of data. They were extensively used starting in 1972 as a data entry media ideally suited to replace 80-column punched cards. Card readers were in turn replaced by diskette readers. By 1978 most of IBM's and other manufacturers' punched-card, or "unit record equipment" such as punch machines, punched card verifiers, sorters, collating machines, card readers, etc., had been discarded, replaced by floppy diskette units, and in the process, saved millions of tons of cardboard paper worldwide each year.
Floppy diskettes 5¼" and 3½" in diameter, having higher data densities and larger capacities, became important storage devices for the personal computer developed in the late 1970s and remained a standard component of computers until the early 2000s.
US Patent Issued to Western Digital Technologies on May 10 for "Heating a Head Disk Assembly for a Time Interval Prior to Writing Spiral Servo Tracks to the Disk" (Malaysian Inventors)
May 13, 2011; ALEXANDRIA, Va., May 13 -- United States Patent no. 7,940,487, issued on May 10, was assigned to Western Digital Technologies...