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Traditional storage mediums

A brief history of Hard Drive Technology

In 1950, Engineering Research Associates of Minneapolis, USA,  built the first commercial magnetic drum storage unit for the U.S. Navy, the ‘ERA 110’.  It could store one million bits of data and retrieve a word in 5 thousandths of a second.

In 1956 IBM invented the first computer disk storage system, the 305 RAMAC (Random Access Method of Accounting and Control).  This system could store five MBytes.  It had fifty, 24-inch diameter disks!

By 1961 IBM had invented the first disk drive with air bearing heads and in 1963 they introduced the removable disk pack drive.

In 1970 the eight inch floppy disk drive was introduced by IBM.  My first floppy drives were made by Shugart who was one of the "dirty dozen" who left IBM to start their own companies.  In 1981 two Shugart 8 inch floppy drives with enclosure and power supply cost me about $350.00.  They were for my second computer.  My first computer had no drives at all.

In 1973 IBM shipped the model 3340 Winchester sealed hard disk drive, the predecessor of all current hard disk drives.  The 3340 had two spindles each with a capacity of 30 MBytes, and the term "30/30 Winchester" was thus coined.



In 1980, Seagate Technology introduced the first hard disk drive for microcomputers, the ST506.  It was a full height (twice as high as most current 5 1/4" drives) 5 1/4" drive, with a stepper motor, and held 5 Mbytes.  My first hard disk drive was an ST506.  I cannot remember exactly how much it cost, but it plus its enclosure, etc. was well over a thousand dollars.  It took me three years to fill the drive.  Also, in 1980 Phillips introduced the first optical laser drive.  In the early 80’s, the first 5 1/4" hard disks with voice coil actuators (more on this later) started shipping in volume, but stepper motor drives continued in production into the early 1990’s.   In 1981, Sony shipped the first 3 1/2" floppy drives.

In 1983 Rodime made the first 3.5 inch rigid disk drive.  The first CD-ROM drives were shipped in 1984, and "Grolier’s Electronic Encyclopaedia," followed in 1985.  The 3 1/2" IDE drive started it’s existence as a drive on a plug-in expansion board, or "hard card."  The hard card included the drive on the controller which, in turn, evolved into Integrated Device Electronics (IDE) hard disk drive, where the controller became incorporated into the printed circuit on the bottom of the hard disk drive.   Quantum made the first hard card in 1985.

In 1986 the first 3 /12" hard disks with voice coil actuators were introduced by Conner in volume, but half (1.6") and full height 5 1/4" drives persisted for several years.  In 1988 Conner introduced the first one inch high 3 1/2" hard disk drives.  In the same year PrairieTek shipped the first 2 1/2" hard disks.

In 1997 Seagate introduced the first 7,200 RPM, Ultra ATA hard disk drive for desktop computers. Later milestones for IDE DMA, ATA/33, and ATA/66 were :

  • 1994 DMA, Mode 2 at 16.6 MB/s
  • 1997 Ultra ATA/33 at 33.3 MB/s
  • 1999 Ultra ATA/66 at 66.6 MB/s

In 2000 IBM tripled the capacity of the world’s smallest hard disk drive.  The drive held one gigabyte on a disk, was the size of an American quarter.  In retrospect, the world’s first gigabyte-capacity disk drive, the IBM 3380, introduced in 1980, was the size of a refrigerator, weighed 550 pounds (about 250 kg), and had a price tag of $40,000.

Types of Hard Disk Technology

RAID – Redundant Array of Inexpensive Drives

RAID technology stores your data on more than one drive to make sure nothing gets lost and to allow recovery of data from failed disk drives without shutting the system down.  RAID uses an assembly of disk drives, known as disk array, that operates as one logical storage unit.  The advantage of RAID, is because it’s a theoretical implementation, it can be implemented on any storage system with random data access, such as magnetic hard drives, optical storage, magnetic tapes, etc.  When the data transfer rate is an issue thought, the fastest SCSI hard drives are typically used. 

RAID allows for the immediate availability of data and, depending on the RAID level, recovery of lost data.  RAID levels provide redundancy of data at a various levels. (RAID Levels 0 , 1 & 5, 10).  Each of these levels uses a different ‘topology’ and method of backing up the data.  The more powerful the level, the more redundant and recoverable the data will be, and not surprisingly, the more expensive it will be to implement.

Small Computer Systems Interface

SCSI (pronounced scuzzy) is the acronym for Small Computer System Interface.  SCSI is a high performance peripheral interface that can independently distribute data among peripherals attached to the PC. It is generally regarded to be more suitable for high-end computer systems which require maximum possible performance than for the home user.

SCSI provides for higher data transfer rates and less CPU load than ATA (which we will see soon) but has higher cost and complexity.  SCSI is now available in several variations including, Fast SCSI, Fast Wide SCSI, Ultra SCSI, Wide Ultra SCSI, Ultra2 SCSI and Wide Ultra2 SCSI.  Each of these evolutions provides significant improvements in bus speed, bus width and possible connected devices.

S/ATA : Serial / Advanced Technology Attachment

ATA was the standard bus interface on the original IBM AT computer, and is the official ANSI (American National Standards Institute) standard term. Also known as IDE (Integrated Drive Electronics)

Most motherboards on modern computers come as standard, with two ATA 40-pin connectors each capable of supporting 2 devices (one master and one slave).

Serial ATA is the next -generation internal storage evolution and is designed to replace parallel ATA technology.  Serial ATA was introduced at 150Mbytes/sec, but is planned to support up to 600Mbytes/sec, as it evolves over a 10 year development roadmap.

SATA/ATA drives are more cost effective than the IDE technology, but currently not as fast.  It is therefore mainly used in domestic PC’s and standard office workstations. 

How a Hard Drive Works

A hard disk uses round, flat disks called platters, coated on both sides with a special media material designed to store information in the form of magnetic patterns. The platters are mounted by cutting a hole in the center and stacking them onto a spindle. The platters rotate at high speed, driven by a special spindle motor connected to the spindle. Special electromagnetic read/write devices called heads are mounted onto sliders and used to either record information onto the disk or read information from it. The sliders are mounted onto arms, all of which are mechanically connected into a single assembly and positioned over the surface of the disk by a device called an actuator. A logic board controls the activity of the other components and communicates with the rest of the PC.

Each surface of each platter on the disk can hold tens of billions of individual bits of data. These are organized into larger "chunks" for convenience, and to allow for easier and faster access to information. Each platter has two heads, one on the top of the platter and one on the bottom, so a hard disk with three platters (normally) has six surfaces and six total heads. Each platter has its information recorded in concentric circles called tracks. Each track is further broken down into smaller pieces called sectors, each of which holds 512 bytes of information.


The entire hard disk must be manufactured to a high degree of precision due to the extreme miniaturization of the components, and the importance of the hard disk’s role in the PC. The main part of the disk is isolated from outside air to ensure that no contaminants get onto the platters, which could cause damage to the read/write heads.




The first PC hard disks had a capacity of 10 megabytes and a cost of over $100 per MB. Modern hard disks have capacities approaching 300 gigabytes and dropped below US$1 per gigabyte last year. This represents an improvement of 1,000,000% in just under 20 years, or around 67% cumulative improvement per year. At the same time, the speed of the hard disk and its interfaces have increased dramatically as well.

The typical Western consumer now generates some 100 gigabytes of data during his or her lifetime, including medical, educational, insurance, and credit-history data.  Hard drive costs have never been so economically viable, allowing the purchase of such significant scales of storage capacity at extremely affordable prices.  With the parallel improvements in reliability and access speeds, the acquisition of hardware with which to implement ambitious ‘life caching’ projects utilising a multitude of formats (video, audio etc) is now, more than ever, a reality which can and will be realised.  

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