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

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II  Hard Drives
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IV  First Hard Drives
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III  A Brief History of Hard Drives
(Page 3 of 3)

Magnetic Disks



Then in 1971 a new device was introduced, a single-sided floppy disk drive. This device could load your programs and save your data. This was an incredible advance in personal computing. This revolutionary device was called a floppy disk, with the nickname referring to its flexibility. IBM engineers led by Alan Shugart created this remarkable device. These floppy drives had the capability of randomly accessing your data and were portable. It used an 8-inch flexible magnetic donut housed in a square flexible plastic enclosure with a rectangular hole punched to allow access to the magnetic head for reading and writing. If you needed to take your program or data to another computer to work on it, it was no problem. By today's standards they were very expensive, around $700, but they were much more reliable than punch cards or tape.

Five years later (1976), Shugart Associates went to work for Dr. An Wang to create the 5 1/4" floppy for Wang Laboratories, which was released in 1978. The 5.25" floppy reduced the 50 pins needed for the 8" floppy to a 34-pin cable, still in use today. Five years (1981) after the 5 1/4" floppy story began, Sony released the 3.5" floppy.

[spacer]Tale from a Floppy Pioneer

Originally reported by Richard Mateosian - Review Editor, IEEE Micro Berkeley, CA:

“The disks were 8 inches in diameter and had a capacity of 200K, I think. Since they were so large (!) we divided them into four partitions, each of which we regarded as a separate hardware device -- analogous to a cassette drive (our other main peripheral storage device). We used floppy disks and cassettes mostly as paper tape replacements, but we also appreciated and exploited the random access nature of disks.”

Our operating system had a set of logical devices (source input, listing output, error output, binary output, etc.) and a mechanism for establishing a correspondence between these and the hardware devices. Our applications programs were versions of HP assemblers, compilers, and so forth, modified (by us, with HP's blessing) to use our logical devices for their I/O functions.

The rest of the operating system was basically a command monitor. The commands had mainly to do with file manipulation. There were some conditional commands (like IF DISK) for use in batch files. The entire operating system and all of the application programs were in HP 2100 series assembly language.

The underlying system software, which we wrote from scratch, was interrupt driven, so we could support simultaneous I/O operations, such as keying in commands while the printer was running or typing ahead of the 10 character per second teletype.

The structure of the software evolved from Gary Hornbuckle's 1968 paper, a Multiprocessing Monitor for Small Machines, and from PDP8-based systems, I worked on at Berkeley Scientific Laboratories (BSL) in the late 1960s. The work at BSL was largely inspired by the late Rudolph Langer, who improved significantly on Hornbuckle's model.”



Previous Topic/Section
II  Hard Drives
Previous Page
Pages in Current Topic/Section
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Next Page
IV  First Hard Drives
Next Topic/Section

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