Computer Organization

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Computer Organization
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Computer Hardware

• Central Processing Unit (CPU)
• The heart and brains of a computer
• The device that performs all calculations and
  data manipulation in a computer
• Main Memory (RAM)
• The place the CPU looks for instructions and
  data to process

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Computer Hardware

• Mass Storage (hard drive)
• Holds information not immediately needed by CPU
• Holds massive amounts of data
• Input/Output Devices
• keyboard, mouse, monitor, printer
• Devices used to move information into and out of
  the computer

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Terminology - storage

• bit
• Stands for Binary Digit.
• Smallest unit of storage in a computer
• A single 1 or 0
• byte
• 8 bits
• Used to store single characters. (Sort of)
• ASCII characters

• kilo-
• Thousand
• kilobyte 1,000 bytes
• Actually 210 bytes (1,024)
• mega-
• Million
• Megabyte 1,000,000 bytes.
• Actually 220 bytes (1,048,576).
• About 350 pages of text

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Terminology - storage

• giga-
• Billion
• gigabyte 1,000,000,000 bytes
• Actually 230 bytes (1,073,741,824)
• About 360,000 pages of text

• tera-
• Trillion
• terabyte 1,000,000,000,000 bytes
• Actually 240 bytes (1,099,511,627,776)
• About 366 million pages of text

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Terminology - processing power

• Clock speed
• The rate at which a CPU performs its basic
  operations
• CPUs clock speed is measured in gigahertz (GHz)
• Gigahertz billion hertz (billion pulses per
  second)
• 2.4 GHz CPU has a clock speed of 2,400,000,000
  pulses per second
• FLOPS
• Floating point operations per second
• MIPS
• Millions of instructions per second

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Basic Architecture

• Processor (CPU)
• Main Memory
• volatile
• I/O devices
• secondary memory
• communications
• terminals
• System interconnection
• a bus is used to exchange data and control
  information

CPU
Memory
System Bus
Disk Controller
Network Controller
Serial Device Controller
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Device Controllers

• Devices are not connected directly to the system
  bus
• Each device has a device controller between it
  and the system bus
• One controller may have multiple devices
• For example SCSI devices, IDE devices, USB
  devices

CPU
Memory
System Bus
Disk Controller
Network Controller
Serial Device Controller
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Disk Device

• Most modern disk drives are actually composed of
  several disks
• A bank of read/write sensors move together
• The active sensor determines which surface is
  being read/written
• The position of the arms determines which track
  is being read/written

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Zoned Bit Density

• The tracks are divided into zones
• There are more sectors in outer zones than in
  inner zones
• This leads to a more efficient use of disk space
• The disk still spins at a constant angular
  velocity
• But outer tracks have more bits per rotation, and
  so are read faster