Professor Sam Posten III

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Professor Sam Posten III
samuel.posten_at_l-3com.com
IT 102 Section 50
Class Session 4 Storage
http//zorak.monmouth.edu/posten/class4.ppt
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AGENDA

• Bits and Bytes Revisited
• Speed
• Storage
• Primary Memory
• Magnetic Storage
• Optical Storage
• Network Storage
• Hybrid / Portable / Solid State Storage

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Bits and Bytes Revisited

• Bits represent the smallest piece of
  information there is, a single decision point.
  They can represent things like 0/1, on/off,
  true/false, open/close, up/down etc.
• When bits are used as 0/1s, packing 8 of them
  together is called a byte.
• 8 bits 1 byte 1 text character
• Bytes can be mapped to represent 255 different
  text characters through a protocol called ASCII
• For example 01000001 (65) maps to the A
  character, and 00100110 (38) maps to the
  Ampersand
• An extended character set protocol which is used
  for many languages is called Unicode

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Bigger Bits

• Exactly 1024 bytes is called a Kilobyte (KB).
  We round this to 1000 tho, so 34000 bytes would
  be 34KB, even tho its not exact. So 1000B 1KB
• 1,000,000B 1 Megabyte, 1MB
• 1,000,000,000B 1 Gigabyte, 1GB
• 1,000,000,000,000B 1 Terrabyte, 1TB
• 1,000,000,000,000,000B 1 Exabye, 1EB
• 1,000,000,000,000,000,000B 1 Petabyte, 1 PB
• 1 page of text is about 2000 characters so 2KB
• 1 floppy holds 1.5 MB
• 1 CD ROM holds 650 MB
• 1 DVD holds 6.5GB PER SIDE PER LAYER! (DSDL
  20GB)
• Blue Ray DVD for High Def can hold over 50 Gigs!
• Modern Hard Disks hold 1,000 GB (1 TB) or more

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Computer Speed

• Computers speed is rated in Cycles per second.
  One Cycle/sec is called a hertz, or 1hz.
• The original IBM PC operated at 4.77 MILLION
  cycles per second. 4.77 Mhz
• Modern computers operate at more than Three
  BILLION cycles per second. Typically, you can
  buy 3.2 Ghz PCs for under 1000.
• Not only that, but modern PCs do MORE per cycle
  than older PCs, MUCH more!
• Even tho Athlon and PowerPC chips dont have as
  fast a speed rating in Mhz, they often can do
  more work in a cycle than Pentium, so you cant
  compare them evenly that way.

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Primary Memory

• There are two major divisions of Memory, Primary
  and Secondary Storage. Primary storage is that
  memory immediately available to the CPU.
  Information on Secondary storage devices must be
  read in to Primary storage before it can be used!
• Primary Storage is broken down into RAM and ROM
• ROM, or Read Only Memory contents are set at the
  factory, and are permanent and unchanging. They
  are used during the boot cycle to help the
  computer get the OS running. Contents are never
  lost, even when power goes out, but cant be
  accessed by the user. Users dont care how much
  ROM their system has. ROM is often found as part
  of the Basic Input Output (BIOS) of a motherboard
• RAM, or Random Access Memory is empty of contents
  every time you turn the computer on. This is the
  area that stuff is held while you work on the
  PC. Your Data, Applications and OS are all
  loaded in RAM. Its contents are wiped whenever
  power is lost. When you Buy memory for your
  computer, you are buying RAM. Typically, we want
  128 to 512 MB of RAM for a modern PC, and MORE is
  always better!

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Magnetic Disks Tape

• Magnetic Storage devices use the physical
  properties of Magnetism to store data, the same
  way a VCR or Cassette Tape do. Bits are stored
  onto some surface so they are readable by a very
  sensitive magnetic reader.
• Magnetic Tape is used for OFFLINE storage, in
  other words we save info to it and save it in a
  safe place in case of emergencies. The problem
  with tape is that you cant jump to any location
  on it, you have to go from one end to the other
  sequentially.
• Floppy Disks are thin plastic and mylar (think
  those foil balloons!) surfaces, sometimes held
  within a hard plastic shell, with a magnetic
  coating. They dont store much but are VERY
  transportable. They are much slower than Hard
  Disks. It would take over 13000 floppy disks to
  back up a 20GB hard disk!
• Hard Disks are rigid metal platters, which were
  traditionally permanently mounted in a sealed
  enclosure that is typically not visible inside
  the system unit. They offer VAST storage
  capacity and speed, but low portability. Today
  however, materials engineering and USB cabling
  have allowed us to make truly portable external
  hard disks

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Magnetic Disks Tape
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Optical Storage

• Optical storage technology uses the physical
  property of light, in the form of a laser, to
  read information stored in the pits formed in
  the surface of a semi-rigid plastic and metal
  platter.
• CDROM utilizes the Compact Disk format to mass
  produce Read Only Media, like an album you might
  buy at the store, except it holds data other than
  just music. 650MB of storage without compression
• CD-R and CD-RW are one time Recordable and multi
  time Re-Writable Compact Disk media that the user
  can burn on their own desktop. Media is VERY
  cheap and transportable. Quickly replacing
  floppies as the portable recordable format of
  choice.
• DVDROM utilizes the Digital Versatile Disk format
  to mass produce Read Only Media, like a movie you
  might buy at the store, except it holds data
  other than just movies. 6.5GB per layer before
  compression. DVD-R and DVD-RW just now becoming
  cheap enough to be popular. The next generation
  DVDs were in a format war between two major
  camps, Bluray Disk (BD) and HD-DVD. Bluray won.

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Optical Storage
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Network Storage

• By networking computers together, we can get much
  much more than just global communications, we can
  also share resources like printers and hard drive
  storage.
• At MU we have access to a network storage area
  that is unique to each student called the M or M
  Drive.

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Hybrid, Portable, and Solid State Storage

• There are hundreds of interesting storage devices
  out there that provide different sets of
  benefits.
• Some devices tried combining Magnetism and Optics
  and came up rewritable Magneto-Optics. (Jaz
  Disks and Bernoulli)
• Many vendors make storage solutions that aimed to
  give the portability of Floppies with the speed
  and capacity of Hard Disks. CD-R was the first
  technology to really succeed globally in that.
• Some manufacturers made devices that use solid
  state memory chips that dont lose their contents
  when power goes off, this is similar to what is
  used to save games on a Playstation or other game
  console. Were starting to see thumb-drives
  that hold over 64 billion of bytes! (64GB)

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Improvements

• Todays computers are Multi-tasking. That is
  they can have many programs running
  simultaneously.
• Windows DOES support multi-users simultaneously,
  but it is a lame implementation.
• Most software is comprised of many threads, which
  can run independently of each other. Think of
  threads for graphics and sound and user input
  interacting.
• Modern motherboards can support up to 4 CPUs, tho
  having more than one is rare for PCs.
• Most CPUs today are dual core, ie they have 2
  physical Central Processing units in one chip
  package. 4 and 8 core CPUs will launch early
  next year. The PS3 has 8 SPUs which are like
  mini CPUs.
• Processors today are FASTER. They run at more
  cycles per second
• Each cycle can process larger blocks of
  information, up to 64-bit words
• Computers have vastly more storage, 500GB-2TB of
  storage is common, versus 5-20 MB being hard to
  picture how to fill up. 50GB Blu Ray recordable
  disks ersus 640KB floppies!