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Table Of Contents  CertiGuide to A+ (Core Hardware)
 9  Chapter 0100:  Hard Drives

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III  A Brief History of Hard Drives
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V  What is a Hard Drive?
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IV  First Hard Drives

The first hard drives were the result of experiments conducted mostly by IBM. These researchers were trying to find a way to develop a disk drive that would be viable for commercial development. The very first drives were actually not disk drives at all; they were rotating cylindrical drums that the data was stored on using magnetic patterns. The drums were very hard to work with and very large, so they were not practical for commercial use.

The first true hard drives that were developed were designed with the heads touching the surface of the hard drive. This allowed the low-sensitivity electronics to better read the surface of the disk, which was magnetic. The techniques used with these drives were not very sophisticated and did not allow for the surface of the disk to be smooth enough to allow the head to glide over the disk at high speed. The heads would wear out fairly quickly or the magnetic coating on the surface of the disk would wear out.

[spacer]Tale from a Hard Drive Pioneer

Currie Muncie, Director of Advanced Storage at IBM's Almaden Research Center:

"The first guys -- when they started out to try and make these disks -- would take an epoxy paint mixture, grind some rust particles into it, put that in a Dixie cup, strain it through a women's nylon to filter it down, and then pour it on a spinning disk and let it spread out as it was spinning, to coat the surface of the disk."

We've certainly come a long way since then, but the first brown disks were important because they were the first replacements for punch cards.

According to Muncie, the disks "held five megabytes of information which, at the time, replaced sixty thousand punch cards."


What Muncie isn't relating in this story is some competitor's ideas. For example Joseph Smith at Chucking Grinder Co. had disk drives, created with 8 or more 39-inch magnesium disks. These drives had two issues. First, the aluminum on the positioning head had balance issues. When the enclosure started walking across the floor, the drive would stop when it ran out of power cord ;-)

The second issue was one of disposal. Military regulations required that obsolete data be burned. Magnesium is the stuff that emergency flares are made of. Can you imagine what happened at an US Army burning site when they threw that much magnesium into a fire?

But it wasn't the storage capacity of the new disks that was impressive. It was the fact that any record -- the equivalent of one punch card -- could be accessed at random in less than one second. Of course, that five megabyte convenience was about the size of a very large refrigerator and cost about ten thousand dollars per megabyte.

The story from this IBM researcher, doesn't mention that this was a rogue project. Hiding in a small town called San Jose, California twelve hours away from IBM headquarters. When the head honchos wanted the project killed, due to budgetary constraints, they hid the project and kept going.

The breakthrough in hard drives came in the 1950's when IBM engineers figured out how to make the heads ride above the surface of the disk without touching it and be able to read the data stored on the drive as it passed underneath it. This revolution formed the basis for the modern hard drive.

[spacer]The Hard Drive is 46 Years Old

Introduced on September 13, 1956, the IBM 305 RAMAC (Random Access Method of Accounting and Control) was the first production hard drive. It had a capacity of 5 million characters (approx. five megabytes) on 50 disks each 24 inches in diameter. Its density was about 2,000 bits per square inch. The data transfer rate was 8.800 bytes per second.


As the technology was developed all of the components and performance of the drives improved. In 1962 IBM introduced the model 1301-Advanced Disk File. This disk had floating heads, reducing this distance from the disk from 800 to 250 micro inches, above the surface of the drive and was able to increase the data transfer rate, density and capacity.

The model 3340 disk drive, introduced by IBM in 1973, is considered the father of the modern hard drive. This unit had 2 spindles, one permanent and the other removable. Each had a capacity of 30MB. This disk was referred as the "Winchester" drives because of the Winchester 30-30 rifle. (Which comes from a remark from one of the engineers who said, "That’s as fast as a Winchester.")

This drive was the first one with a sealed internal environment and an improved "air bearing" system that reduced the height of the heads to 17 micro-inches over the disk.

Al Shugart returns to the story, in 1979, forming a company called Seagate, which distributed the first 5.25" form factor hard drive used in PC's.

This drive, the Seagate ST-506, featured a four head design and had a capacity of 5MB. IBM chose the next generation of this drive, the ST-412, a 10MB Disk, for it's IBM PC/XT. It became the first hard drive widely sold in a PC.


Previous Topic/Section
III  A Brief History of Hard Drives
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V  What is a Hard Drive?
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